Financial capability of people living with Parkinson’s disease – A case-control study

Abstract

Parkinson’s disease (PD) is a neurodegenerative disorder affecting 1% of people older than 60 years. One of the abilities that seems vulnerable to the cognitive impairments associated with PD is financial capability. This explorative study aimed to evaluate the extent and type of problems in financial capability of people with PD without a diagnosis of dementia. Participants were 31 people with PD and 62 matched controls. Participants completed an extensive test-battery, including measures for financial capability and cognitive functioning. Compared to controls, the PD-group performed significantly poorer on two financial competence tasks and showed a comparable performance on the other financial capability measures. For 45% of the PD-group, cognitive test performance was indicative of mild cognitive impairment, yet no significant difference was observed in overall cognitive functioning between the PD and control group. In the total sample, only small or medium correlations were found between financial competence and cognition, and between financial capability and the contextual factors of income and financial experience. The findings suggest that in the earlier stages of PD, when cognitive impairments are relatively mild, some problems may be observed in financial competence, yet other domains of financial capability appear less affected. The absence of strong correlations between financial competence and overall cognitive functioning indicates that standard neuropsychological assessments seem inadequate to make financial capability determinations. By offering insight into the financial capability of people in the milder stages of PD, the findings of the present study may aid in the development and provision of tailored support.

Keywords:

• Cognitive functioning
• financial capability
• financial competence
• financial performance
• Parkinson’s disease

Introduction

Parkinson’s disease (PD) is a progressive neurodegenerative disorder that affects 1% of people older than 60 years, with incidence rates increasing with age (Tysnes & Storstein, 2017). Representing the most common movement disorder worldwide (Tysnes & Storstein, 2017), the clinical diagnosis of PD is based on three hallmark motor symptoms including bradykinesia, muscular rigidity, and resting tremor (Postuma et al., 2015). Apart from the associated motor symptoms, non-motor symptoms such as affective symptoms (e.g., depression and anxiety) and cognitive impairments are highly prevalent in people living with PD (Poewe, 2008). The cognitive impairments associated with PD most commonly involve the domains of executive functioning, attention, memory, and visuospatial functioning (Kehagia et al., 2010), and are often already present at the early stages of the disease (Pfeiffer et al., 2014). Both the motor and non-motor symptoms of PD can lead to functional impairments in the instrumental and basic activities of daily life (Foster, 2014). One of the higher-order instrumental activities of daily living that seems vulnerable to the non-motor symptoms associated with PD, and the cognitive impairments in particular, is the capability to manage one’s personal finances (Martin et al., 2013).

Being able to adequately handle financial affairs, including managing cash, purchasing items, paying bills, or taking out insurance, is a key aspect of successful autonomous and independent living (Engel et al., 2016). Problems in financial capability can have far-reaching personal and legal consequences and may lead to financial insecurity, debts, or financial abuse (Dong et al., 2011; Engel et al., 2016; Manthorpe et al., 2012; Marson et al., 2000). Early identification of potential problems in financial capability is therefore relevant to offering the required type and level of support in a timely manner. In people living with neurodegenerative disorders, such as PD, the evaluation of financial capability is particularly warranted, as a decline of cognition may be associated with decreasing financial abilities (Appelbaum et al., 2016, Ariesen et al., 2023, Bangma et al., 2021). Indeed, an individual’s financial capability is known to be dependent on the integrity of cognition, particularly in regard to the domains of executive functioning, attention, learning and memory, social cognition, and language (Appelbaum et al., 2016; Knigth & Marson, 2012; Okonkwo et al., 2006; Pirogovsky et al., 2012). As such, the cognitive domains relevant for financial capability clearly overlap with those commonly affected in people living with PD. Research on the topic of financial capability in people living with PD remains limited, however, as demonstrated by two recent systematic reviews (Ariesen et al., 2023; Bangma et al., 2021). Therefore, a broader evaluation of the construct is still needed for this patient group.

Within the literature on financial capability, the terms financial literacy, ability, competency, capacity, and capability have been used interchangeably, with differences in meaning across scientific disciplines and between countries (Appelbaum et al., 2016; Sherraden, 2013). In the present study, the terminology and conceptualization of financial capability as introduced by Appelbaum et al. (2016) will be adopted to ensure consistency throughout the text. According to the conceptual model of Appelbaum et al. (2016), the construct of financial capability refers to a broad and multidimensional construct, encompassing both financial competence and financial performance. These three constructs are operationalized as follows:

• Financial capability refers to the handling of one’s finances in a way that consistently serves one’s personal needs and goals. This overarching construct includes both financial skills (i.e., financial competence) and daily life financial functioning (i.e., financial performance).

• Financial competence refers to an individual’s financial skills as reflected by their financial knowledge (e.g., knowledge about the value of currencies or banking procedures) and their financial judgment (i.e., the abilities needed to make beneficial financial decisions). Referring to a set of skills, financial competence is typically assessed in a controlled and standardized setting by means of performance-based tasks.

• Financial performance refers to an individual’s degree of success in dealing with financial affairs in the context of the stressors and support resources in their everyday life (i.e., daily life financial functioning). Financial performance requires sufficient financial competence to implement financial decisions in a real-world setting and can be positively and negatively affected by both personal and environmental contextual factors. Personal factors that influence an individual’s financial functioning include a person’s age, gender, education, and their level of financial experience. Environmental factors that can facilitate or hinder financial capability include an individual’s financial resources or income level, and their received level of social support.

The limited number of studies that have focused on financial capability in people living with PD have mainly looked at financial competence by means of performance-based financial tasks (Ariesen et al., 2023; Bangma et al., 2021). Overall, these studies, as summarized in the meta-analysis of Bangma et al. (2021), indicate that, compared to healthy controls, people living with PD show impairments in several aspects of financial competence, including basic monetary skills, knowledge of financial concepts, and bank statement management (Giannouli et al., 2018; Giannouli & Tsolaki, 2014; Martin et al., 2013). Whereas these studies often included people living with PD dementia (PDD) (Bangma et al., 2021), who show global impairments in financial competence (Giannouli et al., 2018; Martin et al., 2013), impairments were also found in several aspects of financial competence in people living with PD with mild cognitive impairments (Martin et al., 2013; Pirogovsky et al., 2014). These findings therefore substantiate the relation between financial competence and cognition, and suggest that an evaluation of financial competence may already be indicated at the earlier stages of PD, when cognitive impairments are still mild. Based on existing research, which mainly involved people living with dementia, including Alzheimer’s disease and PDD, it remains unclear, however, which aspects of financial competence might already be affected in the earlier stages of PD (Bangma et al., 2021). Moreover, whereas the outcomes on performance-based financial tasks can provide an indication of potential problems in financial competence, little can be said about the everyday financial performance of people living with PD, based on these tasks. As an individual’s real-world financial functioning is not solely determined by their level of financial competence, but is also dependent on daily life contextual factors (Appelbaum et al., 2016), broader evaluations are needed to draw a more comprehensive picture of the strengths and weaknesses in financial capability of people living with PD.

The present explorative study will therefore adopt a broad and extensive test battery to further investigate the financial capability of people living with PD as compared to a control group (CG) without neurological disorders or current psychiatric conditions. To add to the current evidence-base, this study will specifically include people in the earlier stages of PD, without a diagnosis of dementia. Within the adopted test battery, various aspects of financial capability and several of the contextual factors thought to be relevant for (everyday) financial functioning will be addressed. Specifically, associations between the financial measures and the contextual factors of income and financial experience will be examined. Furthermore, the overall cognitive functioning of people living with PD will be assessed and compared to the CG, based on their performance on a wide range of cognitive tests. In order to identify to what extent cognitive functioning relates to financial capability, associations between overall cognitive test performance and the financial tasks will be explored. The main objective of this study thence is to evaluate the extent and type of problems in financial capability of people living with PD. In doing so, the outcomes of the present study can potentially aid in the development and provision of tailored support for people living with PD to preserve autonomy in the handling of their financial affairs in daily life.

Methods

Participants

In total, 169 people participated in this study, including 32 people living with PD and 137 control participants, who were between 38 and 90 years old at the moment of participation. Participants living with PD were recruited via clinicians at the department of neurology and memory clinic of the Middelheim General Hospital (ZNA), Antwerp, Belgium, or responded to a call for participants issued via the Parkinson’s association in the Netherlands. All participants in the PD group were diagnosed with idiopathic PD according to the UK Parkinson’s Disease Society Brain Bank Criteria (Hughes et al., 1992). This diagnosis was made prior to and independent of participation in this study. Further inclusion criteria for the PD group were that participants lived independently, and that the participants who were using medication were on a stable dosage for a minimum of one month at the time of assessment. Exclusion criteria were having received surgical treatment for PD (e.g., deep brain stimulation), the presence of PD dementia, the presence of neurological disorders other than PD, and the presence of severe comorbid psychiatric disorders (e.g., major depressive disorder) and/or significant physical conditions that might affect cognition (e.g., severe hypertension, diabetes). The inclusion and exclusion criteria for the PD group were checked based on people’s medical files (for people recruited via ZNA), or based on self-reported medical information (for people recruited via the Parkinson’s association). One participant was excluded from the PD group due to suspected PD dementia and thereby a considerably reduced understanding of test instructions, leading to the final inclusion of 31 people living with PD. Control participants were recruited through advertisement, or via the personal contacts of the researchers, and were informed about the study via word-of-mouth, e-mail, or social media. Participants in the CG were free of self-reported neurological disorders and current severe psychiatric disorders (e.g., major depressive disorder) and did not have significant self-reported physical conditions that might affect cognition (e.g., severe hypertension, diabetes). As the factors age, educational level, and gender can influence financial capability (Appelbaum et al., 2016; Bangma et al., 2017) as well as cognitive functioning (e.g., Scheffels et al., 2023), and the control participants (n = 137, Mage = 61.1 ± 9.4; 61% female; 66% high educational level) differed considerably from the 31 PD participants in number and characteristics, each PD participant was matched, as closely as possible, to two control participants in terms of age, educational level, and gender. During the matching procedure, priority was given to match the PD participants to the control participants regarding educational level, as in a previous study that used the same test battery, this factor in particular was found to be a significant predictor for financial competence (see Bangma et al., 2017). From the control participants who were suitable matches regarding education, those people were selected for inclusion in the analyses who were of a similar age, and preferably of the same gender as the PD participant they were matched to. Therefore, the data of 31 PD participants and 62 control participants were used for analysis, meaning 75 control participants were excluded during the matching procedure.

Demographic and clinical characteristics

The demographic and clinical characteristics of the PD group and CG are presented in Table 1. To classify the completed level of education of the participants, the Dutch Verhage scale was used (Verhage, 1964). In line with this scale, a Verhage coding of 1–4 was classified as a low educational level (completion of a primary level of education, or lower levels of secondary education), a coding of 5 was classified as a medium educational level (completion of an average level of secondary education), and a coding of 6 or 7 was classified as a high educational level (completion of a high level of secondary education, or a university degree). As indicated in Table 1, the PD group and CG differed significantly (p ≤ .01) regarding scores on the Dutch National Adult Reading Test (NLV; Schmand et al., 1991), the classification of self-reported work status, the Mini Mental State Examination (MMSE; Folstein et al., 1975), the Instrumental Activities of Daily Living scale (IADL; Lawton & Brody, 1969), and the depression sub-score of the Hospital Anxiety and Depression Scale (HADS; Spinhoven et al., 1997). Groups did not differ significantly regarding the other demographic or clinical characteristics. Notably, observed scores on the Questionnaire for Impulsive Compulsive Disorders in Parkinson’s disease (QUIP; Weintraub et al., 2012) indicate that the groups were comparable regarding symptoms of impulse control and related disorders. Whereas impulse control disorders are a common side effect of PD medication (Zhang et al., 2021), investigating the (additive) effect of these disorders on financial capability was beyond the scope of the present study.

Table 1. Demographic and clinical characteristics of the PD group (n = 31) and CG (n = 62).

Demographic characteristics	PD group	CG	p-value
Age range	52–83	49–87	–
Age M (SD) in years	65.7 (7.4)	65.6 (8.0)	.963^a
Gender male:female	19:12	29:33	.187^b
Education level %			.800^c
Low (Verhage coding 1–4)	25.8	19.4
Medium (Verhage coding 5)	19.4	25.8
High (Verhage coding 6–7)	54.8	54.8
IQ estimation (NLV) M (SD)^e	101.2 (14.2)	114.9 (16.7)	< .001^a*
Work status %			.009^b*
Full-time	3.2	24.2
Part-time	3.2	17.7
Retired	64.5	48.4
Other (e.g., voluntary work, sickness benefits)	29.1	9.7
Clinical characteristics
UPDRS-III (motor score) M (SD)^f	30.3 (12.1)	–	–
Hoehn and Yahr staging %^g		–	–
1	20
2	46.7
3	33.3
MMSE M (SD)	28.4 (1.6)	29.2 (1.2)	.005^d*
Range	24–30	26–30	-
Lawton & Brody IADL (total score) M (SD)^h	0.97 (1.3)	0.26 (0.7)	< .001^d*
HADS M (SD)
Depression score	4.8 (3.4)	3.1 (2.9)	.007^d*
Anxiety score	5.7 (3.2)	4.4 (3.1)	.026^d
QUIP (total score) M (SD)	16.4 (12.9)	12.3 (11.1)	.038^d

Abbreviations (in alphabetical order). CG = Control Group. HADS = Hospital Anxiety and Depression Scale. IADL = Instrumental Activities of Daily Living. IQ = Intelligence Quotient. M = mean. MMSE = Mini Mental State Examination. NLV = National Adult Reading Test – Dutch Version. PD = Parkinson’s disease. p-value = probability value. QUIP = Questionnaire for Impulsive-Compulsive Disorders in Parkinson’s disease. SD = Standard Deviation. UPDRS = Unified Parkinson’s Disease Rating Scale (Goetz et al., 2008). Note. Groups were matched for age, educational level, and gender. ^aBetween-group difference evaluated with two-tailed t-test. ^bBetween-group difference evaluated with Pearson’s chi-Square test. ^cBetween-group difference evaluated with two-tailed Mann-Whitney U test. ^dBetween-group difference evaluated with one-tailed Mann-Whitney U test. ^ePD Group: n = 29, CG: n = 60. ^fn = 29. ^gn = 30 (valid percentages reported). ^hPD Group: n = 30, CG: n = 62. *p ≤ .01.

Ethical approval

This study was approved by the medical ethical committee of the University Medical Center Groningen (UMCG), Groningen, the Netherlands (No.: NL54161.042.15) and by the medical ethical committee of ZNA, Antwerp, Belgium (No.: B009201731664/4919). Prior to participation, all participants were informed about the study by means of an information letter. Further, they were informed, both orally and in writing, that participation was voluntary, and that they could withdraw from the study at any time. Prior to the assessment, all participants signed a written informed consent. Participants did not receive monetary compensation for participation.

Procedure

This study comprised four self-report questionnaires and a comprehensive test battery including five performance-based tests on financial capability (Table 2) and a wide range of standardized neuropsychological tests to assess cognitive functioning (Table 3). All questionnaires and performance-based tests were administered in Dutch. The questionnaires were completed at home, prior to the assessment. The assessments were administered individually and took place at one of two hospitals involved (i.e., ZNA or UMCG), at the University of Groningen, or, for some participants in the PD group, at their homes. In case of the latter, the environment was standardized to the largest extent possible (e.g., removal of distractors). PD participants were all assessed by a trained neuropsychologist (i.e., A.D.A., D.F.B, or J.L.J). Control participants were either assessed by a neuropsychologist (D.F.B or J.L.J.), or by extensively trained Master students from the clinical neuropsychology Master’s program of the University of Groningen. PD participants stayed on their regular dosage of (PD) medication during the assessment. The tests were performed consecutively and in a relatively fixed order, with an approximate duration of 3.5 h (for an overview of the test sequence; see S1 Procedure). For some PD participants, the test battery was shortened when administration of the entire test battery was too fatiguing. If the battery was shortened, administration of the financial capability tests was prioritized. The assessment procedure included a minimum of one break of approximately 15–20 min, but participants could request as many breaks as needed to minimize the effects of fatigue on their test performance.

Table 2. Instruments used to assess financial capability.

Instrument	Description	Scoring	Psychometric properties
Financial Questionnaires
Financial Decision Style questionnaire (FDS) (Bangma et al., 2017)	Used to evaluate to what extent individuals apply a certain decision-making style when making financial decisions. Differentiates between 5 financial decision-making styles: Rational style: characterized by the logical or systematic evaluation of choice options. Intuitive style: characterized by a relying on feelings or emotions when making decisions. Dependent style: characterized by the requirement of other people’s advice when making a choice. Avoidant style: characterized by avoiding or postponing financial decision-making. Spontaneous style: characterized by impulsive choice behavior.	Consists of 24 items. Items are scored on a scale ranging from 1 (strongly disagree) to 5 (strongly agree). Sum-scores are calculated for each decision-making style: Rational style (range 5–25). Intuitive style (range 5–25). Dependent style (range 5–25). Avoidant style (range 5–25). Spontaneous style (range 5–20). A higher sum-score on a subscale indicates a more frequent use of that decision-making style.	Internal consistency (range): Acceptable –Excellent: Rational style: α = .82 Intuitive style: α = .75 Dependent style: α = .79 Avoidant style: α = .93 Spontaneous style: α = .81 (Bangma et al., 2019)
Impulsive Buying Questionnaire (IBQ) (Bangma et al., 2017)	Used to evaluate an individual’s impulsive buying tendency. Includes 3 subscales that represent components of impulsive buying: Cognitive component: refers to thoughts of buying on impulse and the urge to buy on impulse. Affective component: refers to emotions and feelings that lead to impulsive buying behavior. Situational component: refers to the availability of time and money needed to execute an impulsive purchase.	Consists of 31 items. Items are scored on a scale ranging from 1 (strongly disagree) to 4 (strongly agree). Sum-scores are calculated for each component: Cognitive component (range 15–60). Affective component (range 12–48). Situational component (range 12–48). A total score (range 27–108) is calculated by adding the affective and cognitive component sub-scores (the situational component is still experimental (Bangma et al., 2017)). A higher total score indicates a stronger overall impulsive buying tendency.	Internal consistency (range): Low – Good: Cognitive component: α = .82 Affective component: α = .82 Situational component: α = .07 IBQ total score: α = .89 (Bangma et al., 2019)
Financial Competence Tasks
Financial Competence Assessment Inventory (FCAI) (Dutch version; (Bangma et al., 2017), updated and translated from; (Kershaw & Webber, 2004, 2008))	Used to evaluate an individual’s financial competence, particularly on the level of financial knowledge. Includes 6 subscales that represent dimensions of financial competence, and provide information about an individual’s relative strengths and weaknesses regarding each dimension: Financial abilities: e.g., the ability to understand the information presented on bills. Financial judgment: e.g., identifying and understanding items on a bank statement. Financial management: e.g., understanding banking protocols. Financial cognitive functioning: e.g., writing a cheque. Debt management: e.g., awareness of own debts. Financial support resources: e.g., assistance seeking skills.	Consists of 38 items, including practical and theoretical questions. Most items are scored on a scale ranging from 0 (no awareness) to 4 (complete understanding), based on the accuracy of the answer that was given. Some items require a yes (0) or no (1) response. Sum-scores are calculated for each dimension: Financial abilities (range 0–36) Financial judgment (range 0–32) Financial management (range 0–22) Financial cognitive functioning (range 0–24). Debt management (range 0–4). Financial support resources (range 0–16) A total score (range 0–134) is calculated by adding all sub-scores. A higher total score indicates a better overall financial competence.	Internal consistency: Total score, financial abilities, financial judgment, financial management, financial cognitive functioning, debt management sub-sores (range): good – excellent (α ≥ .80). Financial support resources: poor (α = .54). (Kershaw & Webber, 2008)
Financial Decision-Making Interview (FDMI) (Bangma et al., 2017)	Used to evaluate an individual’s financial judgment. During the task, 2 vignettes are presented in both oral and written form that each describe a different hypothetical financial situation that requires the main character in the vignette to make a decision (i.e., buying or selling a car, and selling or buying a house). After the presentation of each vignette, the participant is asked to answer questions about the situation, using a semi-structured interview. Includes 5 subscales that represent dimensions of decision-making capacity (Appelbaum & Grisso, 1988; Suto et al., 2005): Identification: the ability to identify a problem. Understanding: the ability to understand information and consider the risks and benefits of a choice. Reasoning: the ability to reason about different options and come to a reasoned decision. Appreciating: the ability to appreciate and evaluate the effects of decisions. Communication: the ability to articulate a final choice.	A score of 0, 1 or 2 is awarded for each question/item, based on the degree of completeness of the answer. Sub-scores are calculated for each vignette based on the average item scores, representing the 5 subscales. The sub-scores on the two vignettes are combined (range 0–4 per domain). A total score (range 0–20) is calculated by adding all sub-scores. A higher total score indicates a better financial decision-making capacity.	Internal consistency: Questionable (α = .67). (Bangma et al., 2019)
Other Financial Tasks
Competence in Decision Rules (CDR) – Adult Decision-Making Competence Battery (De Bruin et al., 2007)	Used to evaluate an individual’s ability to make financial decisions based on specific criteria or decision rules. During the task, 10 scenarios are presented to the participant in written form. For each scenario, the participant has to indicate which of five televisions the main character would choose based on the presented decision rules. During the CDR, the complexity of the scenarios increases.	CDR total score (range 0–10): total number of correct answers for the 10 scenarios. A higher total score indicates a better ability to make financial decisions based on specific rules.	Internal consistency: Acceptable (α = .73). (De Bruin et al., 2007)
Iowa Gambling Task (IGT) (computerized version) (Bechara et al., 1994)	Used to assess risky decision making. During the task the participant is asked to select 1 card from 4 different decks of cards, 100 times. The goal of the participant is to maximize their gain (i.e., to increase the starting capital of €2000). Unbeknownst to the participant, 2 of the 4 decks of cards can be considered advantageous or safe decks (i.e., these decks are associated with relatively low gain, but also with relatively low losses), and 2 of the 4 decks can be considered disadvantageous or risky decks (i.e., selection from these decks is associated with relatively high gain, but also with relatively high losses). Participants have to learn by trial and error which of the decks can be considered advantageous and which disadvantageous.	Total net score: i.e., the total number of choices from the advantageous decks minus the total number of choices from the disadvantageous decks. A higher (positive) net score indicates less risky decision making.	Internal consistency: Low. (Gansler et al., 2011)
Temporal Discounting Task (TDT) (Green et al., 1994)	Used to evaluate the capacity to make decisions that have implications for the future. During the task, 18 different hypothetical scenarios are presented to the participant in both oral and written form. For each scenario, the participant is presented possible delayed gain (i.e., a certain amount of money they could receive in 1 week, 1 month, or 1 year), and is subsequently asked to indicate the lowest amount of money they would accept instead of this gain, at an earlier point in time (i.e., today, in 1 week, or in 1 month). For example, participants are asked how much money they would rather accept today, instead of receiving €500, in a week. The task includes six different time intervals (i.e., today vs. 1 week, today vs. 1 month, today vs. 1 year, 1 week vs. 1 month, 1 week vs. 1 year, and 1 month vs 1 year), and three different possible delayed gains: i.e., €100, €500, €1000).	For each scenario, the percentage of the accepted amount of money relative to the possible delayed gain is calculated. Subsequently, an average total score is calculated for all 18 scenarios.	Internal consistency: Excellent (α = .97). (Bangma et al., 2019)

Note. α = Cronbach’s alpha.

Table 3. Adopted neuropsychological tests per cognitive domain.

Cognitive domain	Subdomain	Test–subtest	References
Memory and Learning	Short-term Verbal Memory	Rey Auditory Verbal Learning Test (RAVLT) – immediate recall	Rey (1958); Van der Elst et al. (2005)
		Wechsler Adult Intelligence Scale – IV (WAIS-IV) – digit span forward	Wechsler (2008); Wechsler (2012)
	Long-term Verbal Memory/Learning	RAVLT – delayed recall	Rey (1958); Van der Elst et al. (2005)
		RAVLT – recognition	Rey (1958); Van der Elst et al. (2005)
	Visual Memory	Doors and People – doors subtest	Baddeley et al. (1994)
Visuospatial Functioning	Visuo-construction	Clock Drawing Test	Sunderland et al. (1989)
	Visual Perception	Kaufman Short Neuropsychological Assessment Procedure (K-SNAP) – figure recognition	Kaufman and Kaufman (1994)
Attention and Psychomotor Speed	Psychomotor Speed	Trail Making Test (TMT) – part A	Reitan (1958)
	Selective Attention/Processing Speed	Stroop Color-Word Test – word card	Stroop (1935); Van der Elst et al. (2006)
	Selective Attention/Concentration	D2 test of attention – concentration performance	Brickenkamp (2007); Brickenkamp and Zillmer (1998)
Executive Functioning	Cognitive Flexibility	TMT – part B / part A	Reitan (1958)
		Semantic Fluency – alternating names of places and pieces of clothing (1 min.)	Bouma (2012)
		Phonemic Fluency – alternating words starting with K and O (1 min.)	Bouma (2012)
	Working Memory	WAIS-IV – digit span backward	Wechsler (2008); Wechsler (2012)
		WAIS-IV – digit span sorting
		WAIS-IV – arithmetic subtest
	Response Inhibition	Stroop Color-Word Test – color-word card / color card	Stroop (1935); Van der Elst et al. (2006)
	Planning Skills	Behavioral Assessment of the Dysexecutive Syndrome (BADS) – zoo-map subtest	Wilson et al. (1996)
Language and Fluency	Word-Finding Difficulties	Boston Naming Test (BNT)	Kaplan et al. (1983); Van Loon-Vervoorn and Stumpel (1996)
	Verbal Fluency	Semantic Fluency – categories “animals” and “professions” (1 min. per category)	Luteijn and Barelds (2004)
		Phonemic Fluency – words starting with “D”, “A”, and “T” (1 min. per letter)	Schmand et al. (2008)

Measures

Financial capability

Bangma and Koerts composed a standardized test battery for financial decision making (Bangma et al., 2017). Seven of the eight instruments from this original battery were used to assess differences in financial capability between the PD group and the CG. Notably, the Financial Decision-Making on Intuition or Deliberation test (FDM-I/D) was excluded from the test battery. The reason for exclusion of this test was that the validity of the underlying construct (i.e., the “unconscious thought advantage”) and of tests comparable to the FDM-I/D has been questioned, and disproved (see Nieuwenstein et al., 2015). In total, the assessment of financial capability therefore included two financial questionnaires, two tasks for financial competence, and three other performance-based financial tasks, which are described in Table 2.

Cognitive functioning

A wide range of standardized, valid and reliable neuropsychological tests were included to assess the overall level of cognitive functioning of the PD group and the CG. Tests were included with regard to the domains of memory and learning, visuospatial functioning, attention and psychomotor speed, executive functioning, and language and fluency. An overview of the adopted neuropsychological tests per cognitive domain is presented in Table 3.

Contextual factors

Personal financial situation

Seven questions were asked about the participant’s personal financial situation. First, participants were asked to indicate their annual gross income, which was scored on a 6-point scale: < €15,000; €15,000–€25,000; €25,000–€35,000; €35,000–€45,000; €45,000–€55,000; > €55,000. Five questions required a yes/no response and included: “Do you receive social security?”; “Do you have a loan or debts other than mortgage or study loans?”; “Do you have a savings account?”; “Do you save actively, that is, do you put money on your savings account on a regular basis?”; “Do/did you save for retirement (i.e., via a professional pension fund, personal savings, or both)?”. Finally, participants were asked to indicate the amount of money they retain each month after deduction of fixed expenses.

Financial experience

Participants were asked about their level of independence in or experience with performing financial activities in everyday life by means of a semi-structured interview. The interview included questions about people’s experience with general financial decision making, financial management, doing groceries, making large purchases, saving money, saving for retirement/retirement planning, debt payment, and taking out health insurance. For most activities, the participant’s level of independence is rated on a 4-point scale: 0 (fully independent), 1 (mostly independent), 2 (performed together with others), 3 (mostly dependent on others), 4 (fully dependent on others/activity is not performed), with the exception of debt payment where the scores of 1 to 4 represent: 0 (no debts), 1 (debts have been paid), 2 (debts are partly paid), 3 (measures to start debt payment are in place), 4 (debts are not paid). For all activities, participants are asked about their level of independence in the past (i.e., premorbid experience/prior to diagnosis (PD group), or several years ago (CG)) and in the present (i.e., in the past 6 months). Higher scores regarding past and present financial experience indicate a larger dependency on others, and therefore reflect less financial experience.

Statistical analysis

To control for an inflation of Type I errors, the significance level in this study was set at a more conservative α = .01, so that results were considered significant when p ≤ .01. Effect sizes were calculated for all between-group comparisons to determine the magnitude or relevance of effects. For most comparisons, effect sizes were calculated as Cohen’s d, with the exception of the Pearson’s chi-square tests, where Cramér’s V was used as the accompanying measure of effect size. Following Cohen’s guidelines, effect sizes (Cohen’s d) in the order of 0.20, 0.50, and 0.80 were interpreted as small, medium, and large, respectively (Cohen, 1969). For all correlational analyses, including Cramér’s V, coefficients in the order of .10, .30, and .50 were interpreted as small, moderate, and large, respectively (Cohen, 1988). Outliers in both study groups were detected visually for each variable, and all identified outliers were rechecked in the raw data. Non-natural outliers were subsequently corrected or removed, whilst natural outliers, i.e., outliers that did not seem to be caused by measurement errors or mistakes in data entry, were not removed from the dataset and were included in the analyses.

Financial capability

Some variables for financial capability (i.e., financial questionnaires and financial tasks) were non-normally distributed, or measured at an ordinal level. To ensure consistency, group differences between the PD group and the CG regarding the variables for financial capability were therefore evaluated by means of two-tailed Mann-Whitney-U tests.

Cognitive functioning

Indication for mild cognitive impairment (MCI)

For the participants in the PD-group, performance on the cognitive variables was compared to available normative data of healthy individuals. Normed scores were mostly adjusted for age, gender and/or educational level, depending on the nature of the variable, and available norm groups. Percentile scores were assigned to all individual normed scores, from which a neuropsychological profile was derived for each PD participant. Based on these neuropsychological evaluations, participants with an indication for MCI were identified. Importantly, based on the neuropsychological evaluations only, no formal MCI diagnosis can be made, as this diagnosis would require subjective reports of cognitive and functional decline (Litvan et al., 2012), which we did not obtain for the present study. Therefore, in line with the diagnostic criteria for MCI in PD by Litvan et al. (2012), people were classified as having an indication for MCI when they presented with impairment on at least two tests either within one cognitive domain, or across two or more cognitive domains. Impairment was defined as a performance of 1.5 standard deviations (SDs) below the demographically appropriate norms (i.e., percentile score ≤ 7).

Cognitive composite score

To assess the overall level of cognitive functioning of the PD group and the CG, a cognitive composite score was computed. To obtain this score, raw scores on the cognitive variables of interest were converted to Z-scores, based on the means and SD of the total sample. Where needed, Z-scores were reversed so that higher scores reflected a better performance on all cognitive variables. Subsequently, the Z-scores of the variables for each cognitive domain were summed and divided by the total number of variables in the relevant domain, resulting in one Z-score per cognitive domain (see Table 3 for an overview of the outcome measures that were included in each domain). The overall cognitive composite score was then calculated as the sum of the domain scores divided by the total number of cognitive domains assessed. As the overall composite score was normally distributed, the between-group difference for overall cognitive functioning was evaluated using a one-tailed t-test. A one-tailed test was adopted, as it was hypothesized that the CG would present with better scores than the PD group on all tests for cognitive functioning, and therefore on the cognitive composite score (see Aarsland et al., 2021; Broeders et al., 2013).

Contextual factors

Personal financial situation

Group differences in annual gross income, and the “amount of money retained each month after a deduction of fixed expenses” were evaluated by means of two-tailed Mann-Whitney-U tests. Between-group differences regarding the dichotomous questions on personal financial situation were evaluated using Pearson’s chi-square tests.

Financial experience

Group differences in past and present financial experience were evaluated using two-tailed Mann-Whitney-U tests.

Associations between financial capability, cognition, and contextual factors

Financial competence and cognition

To explore the relation between cognition and performance on the measures of financial competence, non-parametric correlational analyses (i.e., Spearman’s ρ) were performed in a combined group of PD and control participants. Regarding financial competence, only those financial measures that differed significantly between groups were considered for the correlational analysis with the cognitive composite score, as we specifically aimed to evaluate to what extent overall cognitive functioning could potentially form an explanatory factor for the observed group differences in financial competence.

Income, financial experience, and financial capability

To investigate the potential relations between annual gross income and performances on the financial questionnaires and financial (competence) tasks, non-parametric correlational analyses (i.e., Spearman’s ρ) were performed in a combined group of PD and control participants. In a like manner, non-parametric correlational analyses were performed in a combined group of PD and control participants to investigate the strength of the relations between the measures for financial capability and outcomes on the financial experience interview (i.e., past and present scores). For the correlational analyses with income and financial experience, all financial measures were considered, and both groups were combined, as we aimed to evaluate the associations between these contextual factors and financial capability in the broadest sense.

Results

Financial capability

Financial questionnaires

No significant differences were found between groups on the questionnaires for impulsive buying, or financial decision-making styles (negligible to small effect sizes; see Table 4).

Table 4. Outcomes on financial capability measures of the PD group (n = 31) and CG (n = 62).

Measure	PD group	CG	Z	p-value^a	Effect size^i (99% CI)
IBQ^b Cognitive Score M (SD)	30.9 (4.2)	31.1 (3.9)	0.39	.699	−.05 (-0.64–0.54)
IBQ^b Affective Score M (SD)	25.8 (3.6)	25.0 (4.0)	0.73	.467	.20 (-0.39–0.79)
IBQ^b Situational Score M (SD)	10.1 (1.2)	10.1 (1.1)	0.02	.988	−.02 (-0.61–0.57)
IBQ^b Total Score M (SD)	56.7 (7.1)	56.1 (6.9)	0.20	.839	.08 (-0.51–0.67)
FDS^c Rational Style M (SD)	19.2 (2.8)	19.0 (2.6)	0.68	.495	.08 (-0.50–0.66)
FDS^c Intuitive Style M (SD)	15.3 (4.0)	16.3 (3.8)	1.24	.214	−.26 (-0.84–0.33)
FDS^c Dependent Style M (SD)	15.7 (2.7)	14.3 (3.2)	1.88	.060	.46 (-0.13–1.05)
FDS^c Avoidant Style M (SD)	11.7 (4.0)	10.6 (3.5)	1.28	.201	.33 (-0.26–0.91)
FDS^c Spontaneous Style M (SD)	7.8 (2.7)	8.0 (2.1)	0.36	.717	−.06 (-0.64–0.52)
FCAI^d Financial Abilities M (SD)	26.1 (4.0)	28.5 (4.8)	2.60	.009*	−.51 (-1.10–0.07)
FCAI^d Financial Judgment M (SD)	21.1 (4.9)	22.8 (4.9)	1.47	.142	−.36 (-0.94–0.22)
FCAI^d Financial Management M (SD)	17.0 (3.1)	17.8 (3.0)	1.21	.227	−.24 (-0.81–0.34)
FCAI^d Financial Cognitive Functioning M (SD)	22.8 (1.3)	23.0 (2.2)	1.49	.138	−.15 (-0.73–0.42)
FCAI^d Debt Management M (SD)	3.5 (0.9)	3.9 (0.3)	3.16	.002*	−.74 (-1.32–0.15)
FCAI^d Financial Support Resources M (SD)	10.6 (2.5)	10.7 (3.6)	0.21	.833	−.02 (-0.59–0.56)
FCAI^d Total Score M (SD)	101.3 (10.2)	106.6 (12.7)	2.29	.022	−.44 (-1.02–0.14)
FDMI^e Identification M (SD)	3.6 (0.6)	3.4 (1.0)	0.30	.766	.21 (-0.36–0.78)
FDMI^e Understanding M (SD)	2.7 (1.0)	3.4 (0.8)	3.63	< .001*	−.89 (-1.48–0.29)
FDMI^e Reasoning M (SD)	3.6 (0.7)	3.7 (0.6)	0.77	.439	−.15 (-0.72–0.42)
FDMI^e Appreciation M (SD)	3.3 (0.7)	3.2 (0.9)	0.30	.761	.16 (-0.41–0.72)
FDMI^e Communication M (SD)	3.7 (0.7)	3.9 (0.4)	2.55	.011	−.50 (-1.07–0.08)
FDMI^e Total Score M (SD)	16.8 (2.1)	17.6 (2.1)	2.03	.042	−.36 (-0.93–0.21)
CDR^f Total Score M (SD)	4.7 (2.8)	4.9 (2.4)	0.33	.743	−.05 (-0.64–0.54)
IGT^g Total Score M (SD)	2.7 (27.7)	4.7 (33.8)	0.18	.857	−.06 (-0.68–0.55)
TDT^h Total Score M (SD)	86.4 (9.8)	85.8 (16.3)	1.39	.165	.04 (-0.54–0.62)

Abbreviations (in alphabetical order). CDR = Competence in Decision Rules. CG = control group. CI = confidence interval. IBQ = Impulsive Buying Questionnaire. IGT = Iowa Gambling Task. FCAI = Financial Competence Assessment Inventory. FDMI = Financial Decision-Making Interview. FDS = Financial Decision Styles questionnaire. M = mean. PD = Parkinson’s disease. p-value = probability value. SD = Standard Deviation. TDT = Temporal Discounting Task. Note. ^a Between-group differences evaluated with two-tailed Mann-Whitney U tests. ^b PD group: n = 29, CG: n = 55. ^c PD group = 31, CG = 53. ^d PD group: n = 30, CG: n = 60. ^e PD group: n = 31, CG: n = 62. ^f PD group: n = 28, CG: n = 60. ^g PD group: n = 26, CG: n = 54. ^h PD group: n = 29, CG: n = 61. ⁱ Cohen’s d based on sample means and standard deviations.* p ≤ .01.

Financial competence

Regarding performance on the FCAI, the PD group scored significantly lower (i.e., poorer) than the CG on the subscales “Financial Abilities” and “Debt Management” (medium effect sizes). The scores of the PD group and the CG did not differ significantly for the other FCAI subscales (negligible to small effect sizes), or for the FCAI total score (small to medium effect size). On the FDMI, the PD group scored significantly lower (i.e., poorer) on the subscale “Understanding” (large effect size). The scores on the other FDMI subscales and the FDMI total score did not differ significantly between groups (negligible to medium effect sizes; see Table 4).

Other financial tasks

No significant between-group differences were observed regarding the total scores on the CDR, the IGT, and TDT (negligible effect sizes; see Table 4).

Cognitive functioning

Indication for MCI

Based on the neuropsychological evaluations, 14 out of the 31 participants in the PD group (i.e., 45%) were classified as having an indication for MCI, while 17 out of 31 PD participants (i.e., 55%) were classified as having normal cognition. An overview of the number of PD participants performing ≤ 1.5 SDs below the norms per cognitive variable is presented in the Supplementary Material (see Supplementary Material, Cognitive Assessment S2; Table 1).

Cognitive composite score

The cognitive composite score did not differ significantly between the PD group and the CG (p = .018; medium effect: d = .55; 99% CI = −.03–1.12). An overview of the group average raw scores on all cognitive variables is provided in the Supplementary Material (see Supplementary Material, Cognitive Assessment S2; Table 1).

Contextual factors

Personal financial situation

No significant between-group differences were observed regarding the questions focused on the personal financial situation, including the annual gross income classifications (negligible to small effect sizes; see Table 5).

Table 5. Personal financial situation and financial experience of the PD group and CG.

Question	PD group	CG	Z / χ2	p-value	Effect size (significance/99% CI)
Annual gross income %^a			0.15	.883^b	.03 (n.s.)^h
< €15,000	6.9	5.0
€15,000–€25,000	31.0	21.7
€25,000–€35,000	10.3	26.7
€35,000–€45,000	20.7	21.7
€45,000–€55,000	17.2	10.0
> €55,000	13.8	15.0
Do you receive social security? Yes%/No%	61/39	48/52^c	1.38	.241^d	.12 (n.s.)^i
Do you have a loan or debts other than mortgage or study loans? Yes%/No%	13/87	13/87^e	0.00	.977^d	.00 (n.s.)^i
Do you have a savings account? Yes%/No%	100/0	93/7^e	2.13	.145^d	.15 (n.s.)^i
Do you save actively by putting money on your savings account on a regular basis? Yes%/No%	65/35	72/28^e	5.63	.453^d	.08 (n.s.)^i
Do/did you save for retirement? Yes%/No%	77/33	85/15^e	0.88	.349^d	.10 (n.s.)^i
Amount of money retained each month after deduction of fixed expenses M (SD)^f	1375.0 (831.1)	1270.8 (1182.2)	0.89	.374^b	.10 (-0.50–0.69)^j
Financial experience interview – past M (SD)^g	5.9 (5.5)	4.1 (4.0)	1.45	.147^b	.40 (-0.18–0.98)^j
Financial experience interview – present M (SD)^g	8.2 (6.2)	4.8 (3.9)	2.55	.011^b	.72 (0.12–1.30)^j

Abbreviations (in alphabetical order). CG = control group. CI = confidence interval. PD = Parkinson’s disease. p-value = probability value. n.s. = not significant. SD = Standard Deviation. Note. ^aPD Group: n = 29, CG: n = 60 (valid percentages reported). ^bBetween-group difference evaluated with two-tailed Mann-Whitney U test. ^cn = 60 (valid percentages reported). ^dBetween-group difference evaluated with Pearson’s chi-Square test. ^en = 61 (valid percentages reported). ^fPD group: n = 28, CG: n = 56. ^gPD group: n = 30, CG: n = 61. ^hCohen’s d based on U-statistic. ⁱCramér’s V. ^jCohen’s d based on sample means and standard deviations.

Financial experience

The PD group and the CG did not differ significantly regarding their “past financial experience” ratings (small effect size), and their “present financial experience” ratings (medium effect size) (see Table 5).

Associations between financial capability, cognition, and contextual factors

Financial competence and cognition

In the total sample, the FDMI “Understanding” subscale correlated significantly with a higher cognitive composite score (ρ = .45, p < .001), which could be interpreted as a medium correlate. The cognitive composite score did not correlate significantly with the FCAI subscales “Financial Abilities” (ρ = .25, p = .018) and “Debt Management” (ρ = .01, p = .929) (negligible to small correlates).

Income, financial experience, and financial capability

In a combined group of PD and control participants, higher annual gross income correlated significantly with a lower score on the “Dependent Style” subscale of the Financial Decision Styles questionnaire (ρ = −.29, p = .008), a higher score on the “Understanding” subscale of the FDMI (ρ = .32, p = .003), and a higher total number of correct questions on the CDR (ρ = .30, p = .006). None of the other measures for financial capability were found to correlate significantly with the income level of the participants (see Supplementary Material, S3; Table 1).

Regarding the scores on the financial experience interview, more financial independency/experience in the past correlated significantly with a higher score on the FCAI subscale “Financial Abilities” (ρ = .28, p = .007), a higher FCAI total score (ρ = .34, p = .001) and better performance on the “Communication” subscale of the FDMI (ρ = .36, p < .001). In addition, more financial independency/experience in the present correlated significantly with a higher score on the FCAI subscales “Financial Abilities” (ρ = .29, p = .006), “Financial Management” (ρ = .38, p < .001); and “Financial Support Resources” (ρ = .30, p = .004), a higher FCAI total score (ρ = .41, p < .001), and a better performance on the “Communication” subscale of the FDMI (ρ = .38, p < .001). None of the other measures for financial capability correlated significantly with past or present financial experience/independency. The observed correlations between the contextual factors of income and financial experience and the measures for financial capability were mostly interpreted as negligible or small. In some cases, medium correlations were observed (i.e., ρ > .30) (see Supplementary Material, S3; Table 1).

Discussion

The main objective of the present explorative study was to evaluate the extent and type of problems in financial capability of people living with PD without dementia. To this end, the performance of a group of people living with PD was compared to a CG on an extensive test battery that addresses various aspects of financial capability, cognitive functioning, and several contextual factors thought to be relevant for (everyday) financial functioning. Apart from between-group differences on the financial capability measures, associations between overall cognitive functioning and the financial competence tasks, and between the financial measures and the contextual factors of income and financial experience were explored.

Financial competence of people living with PD

The results of the present study indicate that while people living with PD showed a comparable performance to the CG with regard to most FCAI and FDMI subscales, they performed more poorly on some aspects of financial competence. Specifically, the PD group scored significantly lower than the CG on two subscales of the FCAI, and on one FDMI subscale. This indicates that the PD group had more difficulty than the CG with certain financial abilities or skills (FCAI; Financial Abilities), with the management of their own debts (FCAI; Debt Management), and with the ability to understand information about financial problems and to consider the risks and benefits of a certain choice (FDMI; Understanding) (medium-large effects). Overall, the findings of the present study regarding the financial competence tasks therefore seem to indicate that, while participants living with PD and the CG show a similar performance on several aspects of financial competence, some aspects of financial competence already seem to be affected in the earlier stages of PD. These findings of selective impairments in financial competence appear to be consistent with the limited literature that is available on the financial competence of people living with PD. Indeed, in a recent meta-analytic review, all included studies showed people living with PD to have more problems on financial competence tasks than healthy individuals (Bangma et al., 2021). Whereas previous studies often involved people living with dementia, including PDD, who showed global impairments in financial competence (Bangma et al., 2021), impairments were also found in several aspects of financial competence in people living with PD with mild cognitive impairments (Martin et al., 2013; Pirogovsky et al., 2014). Based on their cognitive test performance, 45% of the people living with PD participating in the present study could be classified has having an indication for MCI, following the diagnostic criteria by Litvan et al. (2012). This percentage closely aligns with the prevalence of PD-MCI observed in previous studies, as summarized in a recent meta-analysis (Baiano et al., 2020), indicating that the cognitive level of the PD group in the present study reflects the population of people in the earlier stages of PD. On a group level, the cognitive impairments of the PD group in the present study were still found to be relatively mild, however, as the cognitive composite score, which can be taken as a measure for overall cognitive functioning, did not differ significantly between the PD group and the CG. Taking these findings into account, the outcomes of the present study thus indicate that, in the earlier stages of PD, when cognitive impairments are still mild, a reduced financial competence may already be observed regarding some aspects of financial knowledge (FCAI) and financial judgment (FDMI), yet most aspects of financial competence still appear to be less affected.

Performance on other financial tasks

Regarding the financial tasks other than the FCAI and FDMI, no significant differences were found between the PD group and the CG, indicating that, for several other aspects of financial capability, problems seem to be absent or less pronounced in the earlier stages of PD. This included measures for decision making based on set rules (CDR), risky decision making (IGT), and temporal discounting (TDT). Whereas previous studies have found that people living with PD show impairments on these types of tasks (e.g., Evens et al., 2016; Pennisi et al., 2023), these findings again align with the inclusion of a PD group with only mild impairments in cognition in the present study. Indeed, it has been suggested in previous studies that a decline of cognition may be associated with decreasing financial abilities (Ariesen et al., 2023; Bangma et al., 2021). Thus, whereas only selective impairments in financial competence were found in the PD group in the present study, which included people with and without indications of PD-MCI, impairments in financial capability could become more pronounced in a group with only PD-MCI, and near global in PDD (see Ariesen et al., 2023; Bangma et al., 2021; Martin et al., 2013). Longitudinal studies are needed, however, to evince the existence of such a decreasing slope in financial capability in relation to the cognitive decline of individuals living with PD.

Financial questionnaires, personal financial situation, and financial experience

Apart from performance-based financial measures, the adopted test battery also included questionnaires on financial decision-making styles (FDS) and the tendency to buy on impulse (IBQ), an interview on financial experience, and several questions regarding people’s personal financial situation. Again, for none of these measures, significant between-group differences were observed. Thus far, research on this kind of financial measures is highly limited, however, meaning that the consistency of the findings, particularly in regard to the decision-making styles, financial experience, and the financial situation of people living with PD, remains to be explored. Impulsive behavior, such as impulsive buying, has received more scientific attention in the context of PD, but mainly in relation to impulse control disorders, which are a common side effect of PD medication (e.g., Bhattacharjee, 2018; Zhang et al., 2021). In the present study, people with current severe psychiatric disorders, such as impulse control disorders, were not included, however, as investigating the (additive) effects of these disorders on financial capability was beyond this study’s scope. Indeed, the observed scores on the QUIP indicated that the PD-group and CG were comparable regarding symptoms of impulse control and related disorders (Table 1).

The absence of significant findings on the participant’s financial situation and the financial questionnaires particularly contrasts the findings of a previous study that explored the financial capability of a different clinical group (i.e., adults with ADHD), in which the same test battery for financial decision making was applied (Bangma et al., 2019). In this study, the personal financial situation of the ADHD group was found to be significantly poorer than the situation of the CG, and people with ADHD were found to adopt a more spontaneous decision-making style and show an increased tendency to buy on impulse. Presumably, an important explanatory factor for these contrasting findings is the age of the participants in both clinical groups. Indeed, as compared to a diagnosis of ADHD (Kieling et al., 2010), the diagnosis of PD is often made later in life (Pagano et al., 2016), when an individual’s financial situation is usually more crystallized, or stable. Similarly, an older age has generally been associated with reduced impulsive behavior (Orgeta, 2009), and specifically with a decreased tendency to buy on impulse (Bangma et al., 2017). Thus, whereas people living with PD may have problems in selective aspects of financial capability, these problems might be less likely to affect their financial situation directly, as certain financial decisions or actions (e.g., saving for retirement) have (partly) been completed at an earlier stage in life (Bangma et al., 2017).

Associations between financial capability, cognition, and contextual factors

Financial competence and cognition

Whereas an individual’s financial competence is known to be dependent on the integrity of cognition (Appelbaum et al., 2016), the present study only observed negligible, small, or medium correlations between overall cognitive functioning (i.e., the cognitive composite score) and the measures of financial competence on which the groups showed a significantly different performance. Specifically, the correlates between the cognitive composite score and the FCAI subscales “Debt Management” and “Financial Abilities” were negligible and small, respectively. A significant, medium correlate was observed between the “Understanding” subscale of the FDMI and overall cognitive functioning. However, it should be noted that the cognitive composite score still only accounts for 20% of the variance in this subscale. As a whole, this absence of strong correlations is in line with previous literature (Pirogovsky et al., 2012, 2014) and indicates that overall cognitive test performance is unlikely to form an important explanatory factor for the problems in financial competence of the PD group. As previously suggested by Pirogovsky et al. (2014), one explanation for an absence of strong associations between overall cognitive functioning and financial competence is that the cognitive and financial competence measures have different underpinnings, each representing distinct functional domains. This is an important suggestion in the context of clinical practice in particular, because it implies that standard cognitive assessments seem inadequate to determine an individual’s level of financial competence. Following this line of reasoning, specially designed tests such as the FCAI and FDMI would need to be adopted to add information about the level of financial competence to the assessments of people living with PD (Pirogovsky et al., 2014).

Another potential explanation for the absence of strong correlations between the cognitive composite score and the financial measures is that contextual factors other than (global) cognition play a larger role in determining an individual’s financial capability. In people living with PD specifically, this could, for example, include affective symptoms, such as depression or anxiety (Appelbaum et al., 2016; Giannouli & Tsolaki, 2019). Other factors that might relate to a person’s financial capability in general, on both the level of financial competence and financial performance, for example include an individual’s age or educational background, their income level, and/or their past and present level of financial experience (Appelbaum et al., 2016).

Income, financial experience, and financial capability

In the present study, relations between the financial measures and the contextual factors of income and financial experience were explored. As expected, a number of small or medium, but significant correlations were observed for both income and financial experience. Still, no significant associations were found between the participant’s income level, or the level of financial experience, and the majority of financial measures. This suggests that, whereas income and financial experience indeed relate to financial competence in particular (i.e., FCAI and FDMI performance), other (contextual) factors may be more strongly associated with financial capability, which should be further investigated by future research. In all likelihood, the underlying basis for an individual’s (problems in) financial capability reflects a complex interplay between global cognition, affective functioning, and a variety of other personal and environmental contextual factors, including income and financial experience. Future studies aimed at gaining further understanding of the financial capability of people living with PD should therefore incorporate the relevance of (everyday) context into their design.

Limitations and future directions of research

The results of the present explorative study should be interpreted with care, and several limitations need to be acknowledged. A first limitation on the study level concerns the size of the PD group. In the present study, only 31 people living with PD were included, and, as participants did not always complete the entire test battery, sample sizes were rather small for several of the outcome measures. To control for an inflation of Type I errors, the significance level in this study was furthermore set at a more conservative α = .01, which has subsequently led to an increased probability of the occurrence of type-II errors. The relatively small sample sizes as well as the conservative alpha level have decreased the power of the analyses. Indeed, post-hoc power analyses have revealed that, given the small sample size of the PD group, adequate power (i.e., ≥ 80%) is only achieved for the large effects that were observed in the present study (i.e., d ≥ .79). This should be taken into account when interpreting the results of the present study and, as this study was explorative in nature, future studies should aim to replicate our findings in a larger sample.

A second limitation on the study level is the composition of the PD group. In this regard it must be acknowledged that most participants in the present study had a relatively high functioning level, as they were asked to complete an extensive and demanding test battery upon study participation. Furthermore, in order to investigate the “pure” effects of PD on financial capability, the present study did not include people living with (severe) psychiatric disorders and/or significant physical conditions that might affect cognition. As outlined above, psychiatric disorders, such as mood and anxiety disorders (Poewe, 2008), are highly prevalent in people living with PD. Exclusion of people with psychiatric disorders comorbid to PD therefore limits the generalizability of the study results. In this context it is important to note, however, that despite having included a relatively well-functioning PD group, the present study did observe a reduced performance in the PD group on some aspects of financial competence as compared to the CG. As financial capability may only worsen with increasing cognitive decline (see Ariesen et al., 2023; Bangma et al., 2021), and/or due to comorbid symptomatology (e.g., Appelbaum et al., 2016; Giannouli & Tsolaki, 2019) these findings indicate that, even in the milder disease stages, attention should be paid to the potential problems in financial capability of people living with PD. Future (longitudinal) research should aim to map the problems in financial capability across the stages of PD, so that people can timely be offered the required type and level of support. In the earlier disease stages, tailored support could, for example, include psychoeducation about the potential decline in financial competence. Furthermore, when financial capability is still largely intact, people could already be offered help with setting up a support system or structure for when problems may increase (e.g., by arranging matters concerning future power of attorney).

A third limitation to the present study concerns the absence of assessments for performance and symptom validity within the adopted test battery. When evaluating participant’s cognitive performance in particular (i.e., examining neuropsychological test data), validity measures are ideally employed in both research and clinical settings to identify potential underperformance and to ensure that the results accurately reflect participant’s cognitive abilities (Roor et al., 2024). Due to, for example, a lack of motivation, task engagement, or fatigue during the assessment (see Schroeder & Martin, 2022), it is thence possible that participants did not consistently perform to the best of their abilities, which may have influenced the results. This potential of underperformance should thus be taken into account when interpreting outcomes on the cognitive tasks in particular (see Supplementary Material, Cognitive Assessment S2; Table 1), and it is recommended that studies aimed at replicating the current study’s findings incorporate performance and symptom validity measures into their design to enhance reliability of the results.

A final limitation of the present study concerns the ecological validity of the study results. To the best of our knowledge, this study was the first to adopt a broad and extensive test battery for the evaluation of the financial capability of people living with PD. Apart from financial competence tasks, other financial measures (e.g., questionnaires), cognitive measures, and several contextual factors relevant for (everyday) financial functioning were taken into account. Whereas the present study was therefore able to shed light on (factors that relate to) the financial capability of people in the earlier stages of PD in a standardized setting, relatively little can be said still, based on the study results, about their financial functioning in everyday life (i.e., financial performance). Indeed, an individual’s real-world financial functioning may be influenced, both positively and negatively, by contextual factors in their personal environment (Appelbaum et al., 2016). In this way, factors that do not necessarily affect financial functioning in a standardized setting, such as the level of support someone receives, may cause a discrepancy between their task and daily life performance (Appelbaum et al., 2016; see Ariesen et al., 2023). Future research should therefore look into the extent to which the problems in financial competence of people living with PD translate to the context of their everyday lives. To this end, future studies should aim to both examine relevant contextual factors, and adopt financial measures that (more) closely relate to real-world financial situations. In this context, it should also be acknowledged, however, that the use of a more direct assessment of people’s everyday financial functioning could raise practical or ethical challenges (Appelbaum et al., 2016).

Conclusion

Overall, the findings of the present explorative study suggest that, in the earlier stages of PD, when cognitive impairments are still mild, problems may already be observed in some aspects of financial competence, on both the level of financial knowledge and financial judgment. On the other domains of financial capability that were assessed in the present study, the PD group performed similar to the CG, indicating that these domains appear less affected in the early disease stages. Financial capability therefore seems to be only relatively mildly impaired in the earlier stages of PD, which could align with the idea that a decline of cognition may be associated with decreasing financial abilities (see Ariesen et al., 2023; Bangma et al., 2021). The absence of strong associations between financial competence and overall cognitive functioning further substantiates the idea that standard neuropsychological assessments are inadequate for the determination of financial capability. Instead, future studies should adopt specially designed tests for financial capability, and incorporate the relevance of (everyday) context into their designs. By examining contextual factors, and by adopting financial measures that closely relate to real-world financial situations, future research can shed light on the problems in financial capability across the stages of PD. By applying a broad and extensive test battery for financial capability, the present study is an important first step in this regard, as it offers insight into the financial capability of people in the milder stages of PD. As such, the findings of the present study can potentially aid in the determination of the required type and level of support for people in the earlier stages of the disease.

Disclosure statement

The authors report there are no competing interests to declare.

Data availability statement

Under the General Data Protection Regulation (GDPR), the data that support the findings of this study are considered pseudonymized rather than anonymized and are therefore still regarded as personal data. Given that the participants of this study did not give informed consent for their personal data to be shared publicly, the supporting data cannot be published due to legal and ethical restrictions. The data are therefore available from JK ([email protected]), upon reasonable request.

Additional information

Funding

The author(s) reported there is no funding associated with the work featured in this article.