Retrograde and semantic amnesia in a case of post-treatment Lyme disease syndrome: did something lead to a psychogenic memory loss? A single-case study

ABSTRACT

Objective: To describe a case of Post-Treatment Lyme Disease Syndrome (PTLDS) with an atypical cognitive profile. Method: A 41-year-old PTLDS patient underwent comprehensive neuropsychological testing and psychological assessment. Results: The patient exhibited impaired intensive attention but preserved selective attention. Executive functions were normal. Short-term and anterograde memory were intact, while retrograde and semantic memory were significantly impaired. The patient also experienced identity loss, specific phobias, dissociative symptoms, and depressed mood. Conclusions: Severe episodic-autobiographical and retrograde semantic amnesia was consistent with some reports of dissociative amnesia. Loss of identity and phobias were also highly suggestive of a psychogenic mechanism underlying amnesia.

KEYWORDS:

• Post-treatment Lyme disease syndrome
• retrograde amnesia
• semantic amnesia
• psychogenic amnesia
• dissociation

1. Introduction

Lyme borreliosis (LB) is a tick-transmitted infection caused by the spirochete bacterium “Borrelia bugdoferi” (Blanc et al., 2014). It is the most widespread vector-borne infectious disease in Europe and in North America (Blanc et al., 2014), but incidence and clinical manifestation vary in different endemic areas. In Western Europe, Lyme Borreliosis incidence was estimated to be 22.04 cases per 100,000 persons per year (Sykes & Makiello, 2017). The most common clinical presentation of LB is the Erythema Migrans rash (skin infection and lesion), often accompanied by “flu-like” systemic symptoms (Sykes & Makiello, 2017). Early treatment with appropriate antibiotics typically resolves the Erythema Migrans rash and prevents late-stage complications (Blanc et al., 2014). However, clinical recovery may be incomplete, and symptoms of fatigue, musculoskeletal pain and cognitive complaints have been reported by approximately 10–15% of treated patients (Aucott et al., 2013). The definition of Post-Treatment Lyme Disease Syndrome (PTLDS) has been proposed to identify “individuals with persistent, otherwise unexplained symptoms after the treatment of documented Lyme disease” (Aucott, 2015). PTLDS diagnosis has been associated with a negative impact on quality of life, and on mental and physical functioning (Aucott et al., 2013; Rebman et al., 2017). Symptoms of depression, including major depressive disorders, have been reported in those patients in several cross-sectional studies (Bujak et al., 1996; Hassett et al., 2008), though depressive symptoms are less common when Lyme Borreliosis is identified and treated early (Aucott et al., 2013; Touradji et al., 2019). Although an objective cognitive decline has recently been found to be rather mild in most of the cases (Berende et al., 2019; Touradji et al., 2019), cognitive symptoms are often subjectively described by PTLDS patients as disturbing and distressing. The most robust neurocognitive findings associated with PTLDS are verbal anterograde memory deficits, particularly detected by free recall, list-learning and verbal fluency tasks (Keilp & Fallon, 2017; Keilp et al., 2006, 2019; Touradji et al., 2019; Westervelt & McCaffrey, 2002). Also, patients with persistent symptoms consistently show psychomotor slowing and, to a variable extent, reduced information processing speed.

In this paper, we describe the case of a patient diagnosed with PTLDS, whose cognitive profile only partially corresponds to what is described in neurological and neuropsychological literature about PTLDS. In fact, in addition to PTLSD’s typical manifestations, a male patient showed severe retrograde episodic-autobiographical and semantic amnesia.

Several clinical cases of amnesia have been described in literature, where memory loss cannot be explained by a medical condition alone (De Renzi et al., 1995; Markowitsch & Staniloiu, 2013; Staniloiu & Markowitsch, 2012). The most recent edition of the Diagnostic and Statistical Manual of Mental Disorders (American Psychiatric Association, 2013), describes dissociative amnesia as “an inability to recall important autobiographical information, - usually of a traumatic or stressful nature – that is inconsistent with ordinary forgetting.”

Traumatic events and psychological stress are considered key players in the onset of dissociative amnesia. The antecedent factors of this kind of amnesia have been found to range from massive psychological traumatic events to the exposition to recurrent psychological stressors or seemingly objective minor incidents. A combination of psychological and physical stressors (e.g., mild traumatic brain injury or electrocution but also more severe brain insults) often predates dissociative amnesia; therefore, it can sometimes be difficult to correctly perform differential diagnosis between neurocognitive (i.e., organically based) and dissociative amnesia. In a relevant review, Staniloiu and Markowitsch (2014) summarized some distinct features that may help distinguish dissociative amnesias from direct organically based amnesias. In dissociative amnesia memory impairment has been found to be typically of a retrograde nature and often limited to the autobiographical domain, in line with the abrupt loss of personal identity. Variable impairments of semantic memory (time-specific knowledge of public events and famous faces and names) have also been described, while learning abilities are usually preserved. On the other hand, organic damage usually leads to anterograde memory and learning dysfunctions, and the loss of retrograde autobiographical information usually appears only in association with them. No loss of identity is mentioned in organically based amnesia (Staniloiu & Markowitsch, 2014), but a cognitive profile characterized by “islands of remembrance” may emerge depending on the severity of the damage.

2. Case presentation

A. is a 41-year-old Italian man, right-handed. He completed a First-Level Degree in Law and a First-Level Master’s Degree (17 years of education) and he was a law enforcement consultant. In 2015, he started showing symptoms of asthenia, psychomotor slowing, night sweats, and attentional difficulties. A. had experienced an episode of low-grade fever accompanied by an Erythema Migrans (EM) rash, during a business trip a few months before the onset of these symptoms. Laboratory exams showed positive serology for Borrelia, with signs of meningeal irritation and T-lymphocytes activation. In March 2016, he was diagnosed with Lyme Disease and he immediately started antibiotic treatment. The response to the therapy was positive: neurological and clinical conditions considerably improved, though psychomotor slowing persisted. As a depressed mood emerged, specific pharmacotherapy with Paroxetine was prescribed.

Six months later, his clinical condition worsened. Lower and upper limb osteoarticular pain (which impaired mobility) and cephalgia were more intense and disabling, while scalp pain and learning difficulties were additionally reported by the patient. Neurophysiological exams (electroencephalogram and electromyography) and neuroimaging (brain computed tomography and magnetic resonance imaging) revealed neither focal nor diffused damage. Reported symptoms were interpreted as persistent outcomes of the infection by the clinicians of the hospital where he was first treated. The clinical picture was compatible with PTLDS.

The patient was not able to return to work due to his physical symptoms and in 2018 he obtained legal recognition of his condition as a workplace-related illness.

Psychological support was additionally suggested to treat the depressed mood and pharmacotherapy for pain was set up.

In 2019 A. was admitted to Don Gnocchi Rehabilitation Service for the treatment of his physical symptoms. The clinical team asked for a neuropsychological evaluation, as the patient’s partner also reported severe memory disorders. She had indeed realized that A. had difficulties in retrieving autobiographical information. According to her description, these memory difficulties appeared after the second worsening of the patient’s clinical picture (September 2016), initially manifested themselves as loss of details of autobiographical events, and progressively extended to entire chunks of time.

The patient signed an informed consent in agreement with the Helsinki Declaration.

2.1. Neuropsychological interview and psychometric evaluation

During the neuropsychological interview, A. was alert and globally oriented to person, place, and time. He was cooperative and adequate in the patient–examiner relationship throughout the neuropsychological assessment.

Marked difficulties in sustained attention emerged: A. showed psychomotor slowing and was fatigued. Many breaks were offered for this reason, neuropsychological tests were not administered when A.’s pain was too strong. The evaluation was interrupted when the patient appeared or reported to be tired.

The patient did not remember any episode of his life prior to the illness and his first memory dated back to about 1 year after the diagnosis of Lyme Disease, “when he had gone to see the sea.” He was not even able to identify “islands of memory” of his life before the illness. Also, both A. and his partner reported that he no longer knew who he was, that he was not able to recognize his relatives and that neither memories nor emotional arousal emerged when he was with them. His autobiographical memory was impaired on three levels: specific events and sensory knowledge (e.g., what someone was wearing on a specific important date), general events (e.g., festivities) and macro-periods of life (e.g., high-school, university, first job). His autobiographical retrograde amnesia was pervasive, and he did not benefit from verbal or visual cues (evocative words or images related to periods or events of his life), thus resulting in the subjective perception of “having nothing left in his mind.” Nevertheless, A. did not appear to be worried about his memory loss and never asked clinicians to help him restore his memories.

A.’s spontaneous language revealed very poor lexical abilities considering his educational level and he seemed to have lost even semantic and conceptual information acquired through education (e.g., basic law knowledge and knowledge of history).

2.1.1. Attention and working memory

Neither selective nor divided attention appeared to be impaired. Indeed, A. was able to focus attention both in single and dual tasks (Giovagnoli et al., 1996; Trail Making Test A, Trail Making Test B, Trail Making Test B-A scores; see Table 1) and never forgot task rules. However, the performance in these tasks and in the Attentional Matrices (Spinnler & Tognoni, 1987; see Table 1) was strongly influenced by A’s psychomotor slowing and fatigue (i.e., he was accurate but slow). A. did not show difficulties in tasks of shorter duration involving working memory, i.e., the ability of mentally manipulating information while performing some other tasks (Table 1). Indeed, both verbal and spatial working memory (Digit and Corsi Span backward; Monaco et al., 2013) were in the normal range.

Table 1. Results of A.’s neuropsychological assessment: tests evaluating attention and working memory.

	Raw score*	Adjusted score	Cut-off score	Equivalent score^1
Attentional Matrices (Spinnler & Tognoni, 1987)	36	21.55	>30	0
Trail Making Test A° (Giovagnoli et al., 1996)	64	73.2	<93	1
Trail Making Test B° (Giovagnoli et al., 1996)	166	203	<282	1
Trail Making Test B-A° (Giovagnoli et al., 1996)	102	130.6	<186	1
Digit Span forward (Monaco et al., 2013)	5	4.48	>4.26	1
Corsi Span forward (Monaco et al., 2013)	5	4.44	>3.46	2
Digit Span backward (Monaco et al., 2013)	5	4.44	>2.65	4
Corsi Span backward (Monaco et al., 2013)	4	3.5	>3.17	2

¹The Equivalent Score (ES) method standardizes regression-adjusted scores into a 5-point ordinal scale that allows drawing clinical judgments: ESs = 0 and 1 meaning “defective” and “borderline” respectively; ES = 2 meaning “low-end normal;” ESs = 3 and 4 meaning “normal.” An ES of zero indicates a performance lower than the fifth centile of the normal population (by keeping the risk of drawing a wrong inference below 5%), and an ES of 4 is equal or better than the median. The limits for ES 1, 2 and 3 are identified by subdividing into three equal segments the range of adjusted scores between the fifth centile and the median via a z-score-based approach (Capitani & Laiacona, 1997, 2017).

Raw and regression-adjusted scores (i.e., raw scores adjusted for age and education with multiple regression analysis), cutoff scores (and normality ranges, to be compared with the patient’s adjusted score) and equivalent scores are reported. References to the normative studies are reported for detailed information about the tests and their Italian standardization. Performances below the cutoffs are in bold. *Raw score indicates number of correct answers except of Trail Making Test which raw score represent time of execution.

2.1.2. Executive functions

A. showed preserved abilities of problem-solving, set-maintenance, cognitive flexibility, inhibition of responding, response preparation, and time and space organization (Table 2a). His performance resulted below average in the Rule Shift Cards subtest of the BADS, probably because the task has to be performed quickly. Notably, tests evaluating Verbal Fluency given specific strategies (Initial Letters and Categories; Table 2b) revealed significant difficulties in lexical access. The performance in the Eyes Test (Serafin & Surian, 2004) was in the normal range and revealed that the social-cognitive ability to attribute mental states to the others was preserved.

Table 2. Results of A.’s neuropsychological assessment: tests evaluating executive functions.

(a)	Raw score*	Regression-adjusted score	Cut-off score	Equivalent score^1
Verbal Fluency – Letters (Carlesimo et al., 1996)	22	12.38	>17.35	0
Verbal Fluency – Categories (Zarino et al., 2014)	21	14.6	>23.58	0
Rey Figure Copy (Caffarra et al., 2002)	35	32.85	>28.88	4
Clock drawing test – Pre-drawn version (Caffarra et al., 2011)	11	10.8	>6.55	3
Raven’s Progressive Matrices (SPM 38)(Caffarra et al., 2003)	27	26.5	>20.72	2
Wisconsin Card Sorting Test (Laiacona et al., 2000)
Global Score	50	64.4	<90.5	2
Perseverative Responses	18	27.4	<42.7	2
Non-perseverative Errors	12	15	<29.9	3
Failure to Maintain the Set	1	1	<3	2
(b)	Raw Score	Standardised Score (Mean = 100; Standard Deviation = 15)
BADS (Giunti OS)
Rule shift cards	18	36.83
Key search	16	135.72
Zoo map	16	113.29
(c)	Raw Score	Percentile	Z-score	Equivalent Score^1
Eyes Test (Serafin & Surian, 2004)	23	43.3	Z = − 0.02	3

^aSee Table 1 for the definition of the Equivalent Score method.

Performances below the cutoffs are in bold and references to the normative studies are reported for detailed information about the tests and their Italian standardization. (a) Raw and regression-adjusted scores (i.e., raw scores adjusted for age and education with multiple regression analysis), cutoff scores (and normality ranges, to be compared with the patient’s adjusted score), and equivalent scores of tests assessing executive functions are reported. (b) Raw and Standardised Scores in 3 sub-tests of the Behavioural Assessment of the Dysexecutive Syndrome (BADS); (c) Raw score, Percentile, Z-score and Equivalent score of the Eyes Test for the assessment of the Theory of Mind. *Raw score indicates number of correct answers.

2.1.3. Memory

The patient underwent a preliminary neuropsychological investigation aimed to detect malingering (Barletta-Rodolfi et al., 2011; Hiscock & Hiscock, 1989). The obtained score did not indicate the presence of possible simulated memory disorders.

Short-term and Anterograde Memory. Short-term memory seemed to be preserved, though the verbal short-term memory appeared to be at the low borderline of the normal range (Table 3). The 15-Word List and the Short Story Tests (Carlesimo et al., 1996) revealed preserved verbal learning and recall of both unstructured (words) and structured (story) material. On the other hand, the delayed recall of the Rey-Osterrieth Complex Figure (Caffarra et al., 2002) revealed difficulties in visuo-spatial learning (Table 3). Indeed, the patient was able to draw the macrostructure of the figure but omitted most of the details.

Table 3. Results of A.’s neuropsychological assessment: tests evaluating short-term memory and anterograde memory.

	Raw score*	Adjusted score	Cut-off score	Equivalent score^1
Digit Memory Test for Malingering (Barletta-Rodolfi et al., 2011)	72/72	-	>36	-
Rey Verbal Learning Test 15-word list (Carlesimo et al., 1996)
Immediate Recall	49	41.26	>28.53	3
Delayed Recall	11	8.70	>4.69	3
Recognition	11/15
False Recognition	1/31
Short Story (Carlesimo et al., 2002)
Immediate Recall (30’’)	5	4.72	>3.10	2
Delayed Recall (20’)	5	4.32	>2.39	2
Forgetfulness	0	0.00	>2.32	4
Rey-Osterrieth Complex Figure – Delayed Recall (10’) (Caffarra et al., 2002)	12	6.00	>9.47	0

¹See Table 1 for the definition of the Equivalent Score method.

Raw and regression-adjusted scores (i.e., raw scores adjusted for age and education with multiple regression analysis), cutoff scores (and normality ranges, to be compared with the patient’s adjusted score), and equivalent scores are reported. References to the normative studies are reported for detailed information about the tests and their Italian standardization. Performances below the cutoffs are in bold. *Raw score indicates number of correct answers.

Retrograde and Semantic Memory. Not only had A. lost his autobiographical memory, but also well-known cultural and historical information.

As mentioned above, A’s partner reported that symptoms of autobiographical amnesia had emerged 6 months after the antibiotic treatment, when the patient’s clinical condition had worsened. The Italian Questionnaire for Remote Events (Budriesi et al., 2002) revealed marked difficulties in describing and placing historical events in time. In addition, the performance in the Famous Face Recognition and Naming Test (Bizzozero et al., 2005) was largely below average, with the patient being able to recognize and name only 2 famous faces out of 63 (corresponding to the raw score of 4487.5; see Table 4).

Table 4. Results of A.’s neuropsychological assessment: tests evaluating retrograde memory (culture and history).

	Raw score	Adjusted score	Cut-off score	Equivalent score^1
Italian Questionnaire for Remote Events (Budriesi et al., 2002)	2/8	1.34	>3.93	0
Famous Face Recognition and Naming Test (Bizzozero et al., 2005)^a
Face Recognition	4487.5	4232.22	>6325	0
Average Semantic	3.5	3.322	>4.431	0
Average Naming	0.33	0.235	>0.50	0

^aSee Table 1 for the definition of the Equivalent Score method.

Raw and regression-adjusted scores (i.e., raw scores adjusted for age and education with a multiple regression analysis), cutoff scores (and normality ranges, to be compared with the patient’s adjusted score), and equivalent scores are reported. References to the normative studies are reported for detailed information about the tests and their Italian standardization. Performances below the cutoffs are in bold. *Raw score indicates number of correct answers, a. Raw score indicates the sum of the weighted scores assigned to each of the 126 images presented (see Bizzozero et al., 2005).

A.’s performance in the Semantic Memory Battery (Sartori & Job, 1988; Sartori et al., 1993) also showed important difficulties in accessing semantic information related to animals and objects (Table 5). The performance was significantly impaired in most of the subtests, such as “naming by picture,” “naming by definition,” “familiarity,” and “Gollin’s degraded pictures.” This semantic deficit was observed during the neuropsychological interview and throughout the assessment as well.

Table 5. Results of A.’s neuropsychological assessment: performances at the Semantic Memory Battery (Sartori & Job, 1988; Sartori et al., 1993.).

	Raw score*	Cut-off score
1. Naming (Picture)
‒‒‒1.1 Animate items	24.00	≥28.31
‒‒‒1.2 Inanimate items	28	≥28
‒‒‒Total	52.00	≥57
2. Naming (Verbal Description)
‒‒‒2.1 Verbal Definition (Animate Items)	6.00	≥6
‒‒‒2.2 Visual Description (Animate Items)	4.00	≥6
‒‒‒2.3 Concrete/Functional Definition (Inanimate Items)	9	≥8
‒‒‒2.4 Abstract Items Definition (Inanimate Items)	8	≥7
3. Word Comprehension	80	80
4. Fluency (Animal Body Parts)	3.30	≥3.41
5. Familiarity (Oral Presentation)
‒‒‒5.1 Inanimate Items – Errors	25.00	<8.44
‒‒‒5.2 Animate Items – Errors	21.00	<10.5
‒‒‒5.3 Total – Errors	46.00	<19
6. Familiarity (Visual Presentation)
‒‒‒6.1 Inanimate Items	16	>14
‒‒‒6.2 Animate Items	8	>5
‒‒‒6.3 Chimeric Objects (Inan. + An.; Inan. + An.)	14.00	>14
‒‒‒6.4 Chimeric Animals (An. + An.)	6	>5
7. Matching Animal Body Parts	1.5	>13.5
8. Gollin’s Degraded Pictures
‒‒‒8.1 Animals	23.00	>48
‒‒‒8.2 Plants	14.00	>23
‒‒‒8.3 Objects	52.00	>71
‒‒‒8.4 Total	89.00	>144
9. Letter Shape	38	>32
10. Skeleton Frame
‒‒‒10.1 Animals	18	>16
‒‒‒10.2 Objects	15	>15
‒‒‒10.3 Total	33	>31
11. Details	11.00	>13

Raw scores and cutoff scores (and normality ranges, to be compared with the patient’s raw scores) are reported. Performances below the cutoffs are in bold. *Raw score represents number of correct answers.

2.2. Psychological examination

A. obtained a score of 18 in the Beck Depression Inventory (Sica & Ghisi, 2007), reporting symptoms of anhedonia, feeling of worthlessness, ambivalence, and poor concentration.

The Toronto Alexithymia Scale (TAS-20; Caretti & La Barbera, 2005) additionally revealed reduced self-awareness, with strong difficulties in recognizing and naming emotional internal states (TAS-20 Score = 68). He reported phobias (fear of contamination and germs, fear of insects, fear of weapons and uniforms) that were accompanied by important emotional activation. These symptoms had a negative impact on A.’s everyday life. He spent whole days confined in his house, either sleeping or watching television (carefully avoiding crime series). The patient insisted on wearing multiple layers of clothing, when forced to go out (e.g., for medical examinations or rehabilitation sessions). He meticulously made sure that his skin was completely protected, even when the temperature outside was high. While the phobia of insects could be attributed to the patient’s medical history, the fear of weapons and men wearing uniforms was more ambiguous. Through investigation, it was found that weapons and uniforms acted as a trigger of symptoms of depersonalization (i.e., feeling as if he were an external observer). The Dissociative Experience Scale (DES-II; Carlson et al., 1993) was therefore presented to the patient but it was not possible to complete the evaluation, as he answered many items declaring that he “did not know” or he “did not remember.” However, from a qualitative point of view, it was notable that the patient identified himself in the items of the scale describing: entire or partial loss of conversations with other people, feeling of being an external observer, lack of familiarity for well-known places, difficulties in determining whether an action had been performed or just planned/thought, lack of memories of actions he was sure he had done (e-mails or signed documents proved it).

We also tried to administer the Millon Clinical Multiaxial Inventory III (Zennaro et al., 2008) but the patient kept repeating that he did not know who he was and what he liked/what he used to do. The personological assessment through specific questionnaires and the individual clinical interview was therefore not successful.

Some information about A.’s psychological functioning was provided by his partner. She described him as a harsh man, whose only dedication was to his work. He was a man of few words and did not talk about his feelings. He had left his family of origin when he was 18 years old and A.’s partner did not know anything about his childhood and adolescence. It was impossible for us to meet his parents, as they live more than 600 km away from the rehabilitation center and did not show up even at the online meetings planned by the rehabilitation team.

Interestingly, A.’s partner described radical personality changes after the onset of the illness. A. had become more affectionate and caring, seeking intimacy and closeness. Furthermore, he had drastically changed his taste in food, music, and clothes (e.g., switching from suits and shirts to sweatshirts and tracksuits). As mentioned above, the patient did not show interest in bringing back his past and frequently enacted avoidance mechanisms. For example, he brought detailed documents about his working life to doctors and other specialists, aiming to avoid questions he did not know how to answer. Also, when he was presented with old pictures of himself, he was reluctant and distressed to such an extent that he happened to vomit. The patient often repeated that he felt as if he “had just woken up from a coma,” “as if the world were upside-down.”

2.3. Functional neuroimaging

After the neuropsychological evaluation, the patient was asked to undergo functional neuroimaging examination to support the diagnostic procedure with measures of brain activity. A. firmly refused. Indeed, functional neuroimaging exams were only available in a hospital far from our rehabilitation center, and A. started to show important symptoms of anxiety just thinking about moving there. He feared that he would again be exposed to insect stings or bites and that he could meet men wearing uniforms on the way there. Our request could undermine the therapeutic relationship. The team therefore decided not to insist further.

3. Discussion

The aim of this case report is to underline and distinguish the main neurocognitive and psychological contributions to A.’s intricate clinical picture. Three years after the diagnosis of PTLDS, the patient still presented marked psychomotor slowing and pervasive deficits in autobiographical and semantic memory. If psychomotor slowing and reduced processing speed are described in literature as symptoms of PTLDS (i.e., Keilp et al., 2006, 2019; Touradji et al., 2019), retrograde amnesia has never been described.

This type of amnesia, together with identity loss and phobias, did not meet the distinct features of organically based amnesia which are reported in introduction (Staniloiu & Markowitsch, 2014), but meets criteria of DSM-5 for dissociative amnesia (American Psychiatric Association, 2013; 300.12).

In fact, A. was unable to recall important personal information, his memory loss was generalized for identity and life history and caused clinically significant impairment in all the areas of functioning.

Patient’s personal memories did not appear to follow the Ribot’ temporal gradient (Harrison et al., 2017) as it usually happens in neurological patients. Instead, he showed an inverse temporal gradient: the most recent memories were well preserved, while the memories of the past were globally destroyed. When we met A., he was able to recognize healthcare professionals, to report what he had done during the day and to correctly and coherently describe the activities proposed in previous sessions with the neuropsychologist. Patient, however, did not remember any episode of his life prior to the illness and his first memory dated back to about one year after the diagnosis of Lyme Disease. He was not even able to identify “islands of memory” of his life before the illness. Also, both A. and his partner reported that he no longer knew who he was, that he was not able to recognize his relatives and that neither memories nor emotional arousal emerged when he was with them.

Lastly, despite the presence of the medical condition, structural neuroimaging and neurophysiological examinations did not reveal any defined structural lesions or physiological alterations that could explain his amnesia. We therefore believe that A.‘s functioning cannot be traced back to Lyme disease, but that the disease represented a factor of psychological vulnerability that contributed to the dissociation. It has been previously proposed that mild trauma may cause “functional inhibition of the access to the information that is already stored” (De Renzi et al., 1995), but that emotional problems and stressful situations may also lead patients to develop dissociative amnesia. Staniloiu et al. (2018) collected 28 cases of patients with autobiographical retrograde memory disorders not attributable to brain damage and underlined the variability of the precipitating factors. Autobiographical amnesia could indeed be preceded by a combination of psychological and physical stressors such as road accidents, minor head injuries and various physical illnesses (e.g., viral infections or meniscus injuries). Due to Lyme Disease and its physical and cognitive consequences, A. was strongly distressed, and he was not able to go back to work. He developed specific phobias, dissociative symptoms, and depression. We speculate that these factors may have created a suitable substrate for dissociative amnesia.

Although encyclopedic knowledge is usually spared in this type of disorder, more than one paper has described cases in which there was impairment in the ability to recall public events and/or famous names and faces (Fujiwara et al., 2008; Kritchevsky et al., 2004), as it emerged from our evaluation. A.’s verbal expression and semantic memory appeared to be strongly compromised. His ability to name and to access semantic information related to animals and objects was impaired. A.’s semantic and autobiographical amnesia was severe and disabling and his memory loss involved a dramatic impairment of historical and cultural information (Table 3). Importantly, naming was also problematic for the patient when it came to his own emotional states (TAS-20). While his ability to name and attribute mental states to other people was preserved (Eyes Test; Table 2c), he was not able to label his internal states even when multiple choices were offered. We, therefore, suppose that A. “s answers to the TAS-20 were not a mere result of his semantic deficit but it could appropriately indicate alexithymia and reduced self-awareness. This latter point is in line with A.”s psychological symptoms of identity loss and depersonalization, which together with a severe retrograde autobiographical amnesia, define the peculiarity of this case.

Interestingly, patient had drastically changed his taste in food, music, and clothes (e.g., switching from suits and shirts to sweatshirts and tracksuits). These type of phenomena are described in cases of dissociative amnesia (Fujiwara et al., 2008), and they are indicative of the “binding power” of memory capable of uniting and integrating personal events, emotions and cognitions, promoting coherence and continuity to the self.

Moreover, the patient’s partner and not A. himself realized that he had difficulties in retrieving autobiographical information. This often happens in cases of dissociative amnesia, when symptom awareness only emerges when personal identity is already lost or when patients face clear evidence of their autobiographical memory loss (e.g., someone brings up or ask about events they do not remember; American Psychiatric Association, 2013). Also, dissociative amnesia can be accompanied by a lack of concern toward the symptoms, similarly to what Pierre Janet described as “la belle indifférence” (1893). In line with this, A. did not appear worried about his retrograde autobiographical memory loss, and never asked the clinicians to help him restore his memories. Instead, he showed intense fear for insects, he strictly avoided crime films on television, showed anxiety about meeting policemen or people in uniform and in general tended to avoid stimuli that resembled weapons or people in uniform.

While the phobia of insects was attributable to the patient’s medical history, the fear of weapons and men in uniform could be interpreted as the “phobia of the past” described by the theorists of “structural dissociation” (Harris, 2007; Van Der Hart & Nijenhuis, 2001; Van Der Hart et al., 2011). According to Van Der Hart and Nijenhuis (2001) generalized dissociative amnesia can imply the loss of premorbid personality and the acquisition of a new sense of self: the “amnesic personality.” However, lost memories could still exert influence on the “new” amnesic personality even in absence of awareness. This would explain the avoidance of internal or external stimuli that could activate traumatic memories of the premorbid personality. In A.‘s case, not only old self-portrait photographs represented triggers destabilizing his amnesic personality, but also weapons and men in uniform could activate memories of his old job (law enforcement consultant), hence the job of his premorbid personality.

The differential diagnosis between dissociative amnesia and malingering is another long-standing issue in psychology that had to be faced in this clinical case. Malingered neurocognitive dysfunctions are defined as volitional exaggeration or fabrication of cognitive dysfunction within forensic and/or clinical settings in order to obtain substantial material gain (e.g., goods, money, or financial compensation for personal injury and disability), or to escape formal duty or responsibility (Brand et al., 2016; Guriel & Fremouw, 2003; Zago et al., 2004). At the time of our evaluation, the patient had already obtained legal recognition of his condition as a workplace-related illness and received financial compensation, thus he did not need further medical reports.

To deepen the assessment of possible simulations, we also administered the Digit Memory Test (Barletta-Rodolfi et al., 2011; Hiscock & Hiscock, 1989). It is important to specify that the test was designed to detect malingered deficits only in anterograde memory and not in retrograde memory. Our decision to administer this test derives from a lack of available measures of semantic and autobiographical memory-simulated deficits (Jenkins et al., 2009). The test clearly spoke up for adequate test engagement and credible test performance. In fact, since the patient precisely complained about learning and anterograde memory difficulties, we expected that if he had been lying, he would have exaggerated his difficulties in tests involving these cognitive abilities. However, though A. was informed that he was being given a test of memory and concentration that individuals with memory problems usually find difficult, he obtained the maximum score, and no malingering was detected. Also, the prolonged clinical observation did not reveal any possible benefit for the patient from feigning retrograde memory impairment. The hypothesis of malingering was therefore excluded.

Adding measures of brain activity would have been of crucial importance to the discussion of this clinical case. Indeed, dissociative disorders seem to emerge from the disruption of functional connectivity (Glisky et al., 2004; Markowitsch, 1999) in neural circuits and areas that are highly sensitive to stress (Bremner et al., 1996) and functional imaging studies (i.e., positron emission tomography, functional magnetic resonance imaging) on dissociative amnesia have provided evidence for metabolic changes in areas agreed to be involved in memory processing. As mentioned above, unfortunately, due to his phobias and to his emotional condition, A. refused to undergo functional imaging. Given Staniloiu and Markowitsch (2014) revision of several single cases of dissociative amnesia with neuroimaging data, we would expect to find a temporo-frontal hypometabolism and disruptions of prefrontal-temporal or cortico-limbic connectivity.

4. Conclusion

This case report highlights the possible association between the diagnosis of a neurological disease and the onset of serious psychological disorders. Here, though it is not possible to come to a certain conclusion, we hypothesize that Lyme Disease and its functional sequelae may have triggered dissociative amnesia. This would be particularly relevant for everyday clinical practice.

Indeed, professionals who take care of patients with persistent cognitive (subjective and/or objective) symptoms should encourage in-depth neuropsychological and psychological evaluations to better define patients’ clinical pictures and the most adequate treatments. To date, there are no evidence-based treatments for dissociative amnesia. The current guidelines on the treatment of dissociative amnesia suggest aiming at the reduction of the threat response triggered by the stimuli related to lost memories (e.g., A.’s reactions to old photos, A.’s phobia for men wearing uniforms), possibly through the creation of a safe environment, psychotherapy, and the “reteaching” and “relearning” of the patient’s autobiographical information (Brandt & Van Gorp, 2006). In line with this, neuropsychological interventions should mainly target attentional and semantic components. Improved attention and adequate anterograde memory abilities would support the relearning process, starting from lost semantic information (less triggering and easier to restore compared to autobiographical events). This could have a positive impact on the patient’s sense of effectiveness and on the quality of his/her interpersonal interactions.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

The data that support the findings of this study are available on request from the corresponding author [RB].

Additional information

Funding

This study was supported and funded by the Italian Ministry of Health – [Ricerca Corrente 2023].