Normal ageing in adults with Down's syndrome: a longitudinal study.
Most adults with Down syndrome show normal ageing in their fifties, so look for other causes before calling memory slips dementia.
01Research in Context
What this study did
The team followed the same adults with Down syndrome for six years. They gave memory and motor tests every year. Most participants were in their 30s, 40s and early 50s.
The goal was to see if normal ageing looks different in this group.
What they found
Memory and hand-speed slowed a little, just like in typical ageing. Only four out of ninety-one people showed possible dementia.
The authors say most adults with Down syndrome age normally through their fifties.
How this fits with other research
Yuwiler et al. (1992) saw no change at all in the same people three years earlier. The new data show tiny drops only after six years, so the picture is stable for a long time.
Rose et al. (2000) looked at a whole population and found lots of dementia. Their wide age net caught younger adults with frontal-type decline, while the present study kept the age focus narrow.
Eisenhower et al. (2006) later showed dementia risk jumps after sixty. Together the papers draw a timeline: expect stability until fifty-five, then watch closely for dementia signs.
Smith et al. (2014) add that behaviour problems do not increase with age, backing the idea that most change is cognitive, not emotional.
Why it matters
When an adult with Down syndrome starts forgetting steps or slowing down, do not rush to label dementia. First rule out hearing loss, depression or poor sleep. Track small changes yearly and save full dementia work-ups for clear, persistent decline after age fifty-five.
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02At a glance
03Original abstract
The ubiquitous presence of the neuropathology of Alzheimer disease (AD) in individuals with Down's syndrome (DS) over 40 years of age suggests that this group of people will exhibit a high prevalence of dementia of the Alzheimer type (DAT) as they age. The present study indicates that there is a clear discrepancy between the presumed presence of AD neuropathology and the clinical expression of DAT among older people with DS. In the first 6 years of a longitudinal study, the present authors compared 91 adults (31-63 years of age) with DS and mild or moderate mental retardation to 64 adults (31-76 years of age) with other forms of mental retardation (MR) on yearly measures of mental status, short- and long-term memory, speeded psychomotor function, and visuospatial organization. The results indicated that, over repeated testing on the verbal long-term memory test, younger participants with DS showed small increases in their scores, while older participants with DS showed very slight decreases. Overall performance scores on this test and a speeded psychomotor task were poorer for both diagnostic groups in individuals aged 50 years and older. The magnitude and type of these selective changes in performance were consistent with performance profiles observed in older healthy adults without mental retardation on tests measuring similar cognitive functions. Only four out of the 91 people with DS in the present sample showed changes in functioning that have led to a diagnosis of possible DAT, and in these individuals, alternative causes of performance declines were concurrently present (e.g. thyroid dysfunction). These findings indicate that some age-associated changes in functioning are related to "normal' but probably precocious ageing among adults with DS. Furthermore, these findings suggest that adults with DS and mild or moderate mental retardation may be at lower risk for dementia during their fourth and fifth decades of life than previous studies have suggested.
Journal of intellectual disability research : JIDR, 1996 · doi:n/a