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Normal ageing in adults with Down's syndrome: a longitudinal study
D A Devenny1, W P Silverman, A L Hill
1New York State University for Basic Research in Developmental Disabilities, USA.
Journal of Intellectual Disability Research : JIDR
|June 1, 1996
Summary
Individuals with Down's syndrome (DS) aged 40+ show less dementia of the Alzheimer type (DAT) than expected, suggesting normal aging rather than dementia. Cognitive changes observed are similar to healthy aging adults.
Area of Science:
- Neuroscience
- Gerontology
- Genetics
Background:
- Individuals with Down's syndrome (DS) often exhibit Alzheimer's disease (AD) neuropathology by age 40.
- This suggests a high prevalence of dementia of the Alzheimer type (DAT) in this population as they age.
- However, the clinical expression of DAT in older adults with DS is not fully understood.
Purpose of the Study:
- To investigate the discrepancy between presumed AD neuropathology and clinical DAT expression in older adults with DS.
- To compare cognitive changes over time in adults with DS versus those with other forms of mental retardation (MR).
Main Methods:
- A 6-year longitudinal study comparing 91 adults with DS (mild/moderate MR) to 64 adults with other MR.
- Yearly assessments included mental status, short- and long-term memory, psychomotor speed, and visuospatial organization.
- Participants ranged from 31 to 76 years of age.
Main Results:
- Younger DS participants showed slight verbal long-term memory score increases; older DS participants showed slight decreases.
- Both groups aged 50+ had poorer performance on verbal long-term memory and psychomotor tasks.
- Only 4/91 DS participants met criteria for possible DAT, with alternative causes for decline present.
Conclusions:
- Age-associated cognitive changes in DS may represent precocious normal aging, not necessarily DAT.
- Adults with DS and mild/moderate MR may have a lower risk of dementia in their 40s and 50s than previously thought.
- Further research is needed to understand the relationship between AD neuropathology and cognitive decline in DS.