Dementia in People with Severe/Profound Intellectual (And Multiple) Disabilities, and Its Natural History

Figures & data

Table 1. Characteristics of three study groups.

Participants’ characteristics	No dementia n = 103	Questionable dementia n = 19		Diagnosed dementia n = 19		p
Age (years, mean ± SD (min.–max.))	64.6 ± 1.1 (43.0–89.0)	61.0 ± 8.9 (47.0–81.0)		65.6 ± 10.1 (48.0–85.0)		0.122
	49.5	36.8		36.8		0.408
Deaths among included participants (%)	12.6	15.8		15.8		0.890
Intellectual functioning: severe; severe/profound; profound (%)	56.3; 1.0; 42.7	68.4; 5.3; 26.3		52.6; 10.5; 36.8		0.195
Presence of syndrome: DS; other genetic syndrome; no/unknown (%)	9.7; 14.6; 75.7	52.6; 0.0; 47.4		63.2; 0.0; 36.8		<0.001*
Autism spectrum disorder: formal diagnosis; signs but no diagnosis (%)	14.6; 27.2	5.3; 21.1		0.0; 21.1		0.449
IQ-score available (%)	2.9	10.5		10.5		0.225
Social-emotional functioning: 0–6 months; 6–18 months; 18–36 months; 3–7 years; not reported (%)	19.4; 18.4; 5.8; 1.9; 54.5	10.5; 15.8; 5.3; 10.5; 57.9		15.8; 10.5; 15.8; 57.9		0.318
Verbal communication: able; no longer; never (%)	39.8; 2.9; 57.3	52.6; 0.0; 47.4		42.1; 5.3; 52.6		0.679
Walking skills: able; never (%)	80.6; 19.4	100.0; 0.0		94.7; 5.3		0.009*
Conditions which could cause dementia-like symptoms			Not reported (%)		Not reported (%)
Vision problems: treated; untreated (%)	25.2; 62.1	36.8; 52.6	0.0	42.1; 57.9	0.0	0.162
Hearing problems: treated; untreated (%)	15.5; 38.8	21.1; 52.6	0.0	26.3; 52.6	0.0	0.257
Epilepsy: treated; untreated (%)	48.5; 10.7	15.8; 15.8	5.3	47.4; 5.3	0.0	0.051
Hypothyroidism: treated; untreated (%)	10.7; 0.0	15.8; 5.3	10.5	36.8; 0.0	10.5	0.022
Depression: treated; untreated (%)	3.9; 1.0	10.5; 0.0	36.8	5.3; 0.0	52.6	0.870
Chronic pain: treated; untreated (%)	4.9; 0.0	10.5; 5.3	73.7	1.5; 0.0	63.2	0.380
Sleep apnea: treated; untreated (%)	1.0; 1.9	0.0; 5.3	78.9	0.0; 0.0	94.7	0.831
Vitamin B12 deficiency: treated; untreated (%)	0.0; 0.0	0.0; 0.0	42.1	0.0; 0.0	36.8	-
CVA (%)	10.7	15.8	63.2	21.1	63.2	0.616
Delirium (%)	1.0	0.0	100.0	5.3	94.7	0.306
Psychoactive medication use
Any psychoactive medication use (%)	72.8	47.4		63.2		0.040*
- Antiepileptics (N03A, %)	51.5	26.4		42.1		0.090
- Antipsychotics (N05A, %)	30.1	21.1		26.3		0.673
- Anxiolytics (N05B, %)	6.8	10.5		10.6		0.789
- Hypnotics and sedatives (N05C, %)	3.9	0.0		5.3		0.458
- Antidepressants (N06A, %)	14.6	10.5		15.8		0.862
- Antidementia (N06D, %)	0.0	0.0		0.0		-
- Opioids (N02A, %)	0.0	0.0		0.0		-
Number of psychoactive medications (% n = 0; 1; 2; 3; 4; not reported)	19.4; 29.1; 26.2; 14.6; 2.9; 7.8	47.4; 31.6; 5.3; 0.0; 10.5; 5.3		31.6; 36.8; 0.0; 15.8; 10.5; 5.3		0.001*

With respect to the prevalence of (un)treated conditions which could cause dementia-like symptoms, one would expect that these conditions were ruled out in the diagnostic process of dementia. Therefore, the proportion of individuals for whom nothing was reported about the prevalence of these (un)treated conditions are presented for both the group with questionable dementia and the group with diagnosed dementia. To compare differences between groups, ANOVA was used for normally distributed continuous data (age) and chi-squared tests were used for categorical data. Symbol: *p <0.05. Abbreviations: CVA, cerebrovascular accident; DS, Down syndrome; max., maximum; min., minimum; SD, standard deviation.

Figure 1. Time-density plot of dementia symptoms reported in clinical records of people with diagnosed dementia. The mean time of onset of a symptom is plotted against the prevalence of that symptom. Dashed lines represent the mean time dementia was first suspected −5.7 years before diagnosis – and the time of diagnosis, respectively. Symbols: ↓, decrease; ↑, increase. Abbreviation: ADL, activities of daily living.

Figure 2. Prevalence of cognitive symptoms per group: no dementia (SPI(M)D), questionable dementia (SPI(M)D + QD) and diagnosed dementia (SPI(M)D + D). From left to right, symptoms are presented from most to least frequently reported for those with diagnosed dementia. Chi-squared tests were used to identify differences between groups. Symbol: *p <0.05. Abbreviation: SPI(M)D, severe/profound intellectual (and multiple) disabilities.

Figure 3. Prevalence of activities of daily living (ADL) symptoms per group: no dementia (SPI(M)D), questionable dementia (SPI(M)D + QD) and diagnosed dementia (SPI(M)D + D). From left to right, symptoms are presented from most to least frequently reported for those with diagnosed dementia. Chi-squared tests were used to identify differences between groups. Symbol: *p <0.05. Abbreviation: SPI(M)D, severe/profound intellectual (and multiple) disabilities.

Figure 4. Prevalence of behavioral and psychological symptoms per group: no dementia (SPI(M)D), questionable dementia (SPI(M)D + QD) and diagnosed dementia (SPI(M)D + D). From left to right, symptoms – either decrease or increase – are presented from most to least frequently reported for those with diagnosed dementia. Chi-squared tests were used to identify differences between groups. Symbol: *p <0.05. Abbreviation: SPI(M)D, severe/profound intellectual (and multiple) disabilities.

Figure 5. Prevalence of motor symptoms per group: no dementia (SPI(M)D), questionable dementia (SPI(M)D + QD) and diagnosed dementia (SPI(M)D + D). From left to right, symptoms – either decrease or increase – are presented from most to least frequently reported for those with diagnosed dementia. Chi-squared tests were used to identify differences between groups. Symbol: *p <0.05. Abbreviation: SPI(M)D, severe/profound intellectual (and multiple) disabilities.

Figure 6. Prevalence of medical comorbidities per group: no dementia (SPI(M)D), questionable dementia (SPI(M)D + QD) and diagnosed dementia (SPI(M)D + D). From left to right, symptoms – either decrease or increase – are presented from most to least frequently reported for those with diagnosed dementia. Chi-squared tests were used to identify differences between groups. Symbol: *p <0.05. Abbreviation: SPI(M)D, severe/profound intellectual (and multiple) disabilities.

Table 2. Number of symptoms per domain.

Domain	No dementia n = 103	Questionable dementia n = 19	Diagnosed dementia n = 19	p
Cognitive symptoms	0 (1), 0–7	3 (3), 0–8	6 (3), 2–8	<0.001*
ADL symptoms	1 (1), 0–5	2 (1), 0–5	2 (3), 0–6	<0.001*
Behavioral and psychological symptoms	3 (2), 0–9	6 (3), 2–9	8 (1), 4–10	<0.001*
Motor symptoms	2 (3), 0–7	4 (4), 0–9	6 (3), 0–9	<0.001*
Medical comorbidities	1 (1), 0–3	2 (1), 1–3	2 (2), 0–3	0.120

The number of symptoms for each domain (median (interquartile range), min.–max.) are presented separately for the groups. Kruskal-Wallis tests were used to compare differences between groups. Symbol: *p <0.05. Abbreviation: ADL, activities of daily living.

Table 3. Predictive values of the number of symptoms per domain for the development of dementia.

Domain	No dementia versus questionable dementia^I		No dementia versus diagnosed dementia^I		Questionable versus diagnosed dementia^II
	OR (95% CI)	p	OR (95% CI)	p	OR (95% CI)	p
Cognitive symptoms	2.12 (1.38–3.26)	<0.001*	3.92 (2.05–7.51)	<0.001*	1.85 (1.08–3.17)	0.025*
ADL symptoms	0.67 (0.36–1.29)	0.240	0.44 (0.18–1.08)	0.730	0.65 (0.31–1.37)	0.260
Behavioral and psychological symptoms	1.67 (1.20–2.32)	0.002*	3.39 (1.61–7.16)	0.001*	2.03 (1.01–4.11)	0.048*
Motor symptoms	1.34 (1.01–1.78)	0.042*	1.67 (1.06–2.64)	0.028*	1.25 (0.82–1.90)	0.310
Medical comorbidities	0.89 (0.37–2.11)	0.790	0.46 (0.12–1.75)	0.250	0.52 (0.16–1.70)	0.280

Multinomial logistic regression was used to identify predictors for the development of dementia. Symbols: ^Ithe reference category was no dementia; ^IIthe reference category was questionable dementia; *p <0.05. Abbreviations: ADL, activities of daily living; CI, confidence intervals; OR, odds ratio.