Fifteen-year follow-up of 92 hospitalized adults with Down's syndrome: incidence of cognitive decline, its relationship to age and neuropathology.
Expect one in five adults with Down syndrome to show dementia by their mid-50s—use PCFT or ABS for mild–moderate ID and watch behavior for profound ID.
01Research in Context
What this study did
Kleinert et al. (2007) followed 92 hospitalized adults with Down syndrome for 15 years. They watched who developed dementia and at what age. Doctors used brain autopsies and two tests: PCFT for thinking skills and ABS for daily living skills.
The team split the group by IQ level. They wanted to see which signs best catch dementia in mild, moderate, and profound intellectual disability.
What they found
One in five adults developed dementia. The middle age of onset was 55.5 years.
For people with mild or moderate ID, falling scores on PCFT and ABS were clear red flags. For people with profound ID, behavior changes and neurological signs were the main clues.
How this fits with other research
Yuwiler et al. (1992) and Bauman et al. (1996) saw almost no cognitive loss over 3–6 years. That sounds opposite. The trick: their adults were younger (27–55) and follow-up was shorter. L et al. kept the camera rolling 15 years and caught the downturn the earlier studies missed.
Rose et al. (2000) already showed high dementia incidence in Down syndrome. L et al. confirm that count and add exact age data plus brain evidence.
Prasher et al. (1995) first listed restlessness, wandering, and incontinence as warning signs. L et al. validate those same behaviors for clients with profound ID and show they hold up over the long haul.
Why it matters
If you serve adults with Down syndrome, plan on screening for dementia once they reach their 50s. Use PCFT or ABS for clients who can test, and track behavior shifts for clients who cannot. Early signs give families time to adjust supports and medical care.
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02At a glance
03Original abstract
BACKGROUND: The clinical and neuropathological features associated with dementia in Down's syndrome (DS) are not well established. Aims To examine clinico-pathological correlations and the incidence of cognitive decline in a cohort of adults with DS. METHOD: A total of 92 hospitalized persons with DS were followed up from 1985 to December 2000. At outset, 87 participants were dementia-free, with a median age of 38 years. Assessments included the Prudhoe Cognitive Function Test (PCFT) and the Adaptive Behavior Scale (ABS), to measure cognitive and behavioural deterioration. Dementia was diagnosed from case records and caregivers' reports. RESULTS: Eighteen (21%) patients developed dementia during follow-up, with a median age of onset 55.5 years (range 45-74). The PCFT demonstrated cognitive decline among those with a less severe intellectual disability (mild and moderate) but not among the profoundly disabled people (severe and profound). Clinical dementia was associated with neuropathological features of Alzheimer's disease, and correlated with neocortical neurofibrillary tangle densities. At the age of 60 years and above, a little more than 50% of patients still alive had clinical evidence of dementia. CONCLUSIONS: Clinical dementia associated with measurable cognitive and functional decline is frequent in people with DS after middle age, and can be readily diagnosed among less severely intellectually disabled persons using measures of cognitive function such as the PCFT and behavioural scales such as the ABS. In the more profoundly disabled people, the diagnosis of dementia is facilitated by the use of behavioural and neurological criteria. In this study, the largest prospective DS series including neuropathology on deceased patients, the density of neurofibrillary tangles related more closely to the dementia of DS than senile plaques. In people with DS surviving to middle and old age, the development of dementia of Alzheimer type is frequent but not inevitable, and some people with DS reach old age without clinical features of dementia.
Journal of intellectual disability research : JIDR, 2007 · doi:10.1111/j.1365-2788.2006.00902.x