Dementia and mortality in persons with Down's syndrome.
Dementia hits roughly 25 % of adults with Down syndrome after 60, and diagnosis flags higher mortality risk.
01Research in Context
What this study did
The team looked at health records of adults with Down syndrome. They wanted to know how many had dementia at each age and who died.
They counted cases across the whole adult life span. The study gives a snapshot, not a follow-up.
What they found
Dementia rates shoot up each decade until age 60. After 60, the curve flattens at about one in four adults.
The flatten is not good news. It happens because people with dementia die sooner, so fewer survive to be counted.
How this fits with other research
Kleinert et al. (2007) tracked the same population for 15 years. They saw 21 % develop dementia and median onset at 55.5. Their data extend the 2006 snapshot by showing when the climb starts.
Yuwiler et al. (1992) and Bauman et al. (1996) seem to disagree. Both found little or no cognitive loss in adults under 55. The gap is age. The 2006 curve rises sharply after 55, so younger cohorts look stable.
Xenitidis et al. (2010) and Farrant et al. (1998) add detail. They list mood, sleep, and psychotic signs that show up once dementia is present. These papers flesh out what the plateau phase looks like day to day.
Why it matters
If you serve adults with Down syndrome, expect dementia risk to jump after 55. Plan annual screens and talk early about living wills. Once dementia is diagnosed, watch for sudden medical decline and coordinate with physicians. The one-in-four rate gives families a clear number for care planning.
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02At a glance
03Original abstract
BACKGROUND: Numerous studies have documented that persons with Down's syndrome (DS) are at an increased risk of Alzheimer's disease (AD). However, at present it is still not clear whether or not all persons with DS will develop dementia as they reach old age. METHODS: We studied 506 people with DS, aged 45 years and above. A standardized assessment of cognitive, functional and physical status was repeated annually. If deterioration occurred, the patients were examined and the differential diagnosis of dementia was made according to the revised Dutch consensus protocol and according to the ICD-10 Symptom Checklist for Mental Disorders. We compared our findings with those reported in the literature. RESULTS: The overall prevalence of dementia was 16.8%. Up to the age of 60, the prevalence of dementia doubled with each 5-year interval. Up to the age of 49, the prevalence is 8.9%, from 50 to 54, it is 17.7%, and from 55 to 59, it is 32.1%. In the age category of 60 and above, there is a small decrease in prevalence of dementia to 25.6%. The lack of increase after the age of 60 may be explained by the increased mortality among elderly demented DS patients (44.4%) in comparison with non-demented patients (10.7%) who we observed during a 3.3-year follow-up. There was no decrease in incidence of dementia in the age group of 60 and above. Our findings are very similar to those published in the literature. Patients with dementia were more frequently treated with antiepileptic, antipsychotic and antidepressant drugs. The history of depression was strongly associated with dementia. CONCLUSIONS: Our study is one of the largest population-based studies to date. We found that despite the exponential increase in prevalence with age, the prevalence of dementia in the oldest persons with DS was not higher than 25.6%.
Journal of intellectual disability research : JIDR, 2006 · doi:10.1111/j.1365-2788.2006.00842.x