Incidence of dementia in older adults with intellectual disabilities.
Adults with intellectual disability face dementia five times more often than typical seniors—screen early.
01Research in Context
What this study did
The team tracked new dementia cases in adults with intellectual disability.
They left out people with Down syndrome to see risk for the rest of the ID group.
Doctors watched a group for years and counted every new diagnosis.
What they found
Dementia appeared five times more often than in the general older population.
The rate was 54 cases for every 1,000 person-years.
Adults with ID but no Down syndrome still face very high dementia risk.
How this fits with other research
Whitehouse et al. (2014) looked only at adults with Down syndrome and saw dementia start around age 55.
That seems earlier than the ID group here, but the papers study different people.
The apparent contradiction is simple: Down syndrome carries extra brain changes, so it is not fair to compare the two groups.
Together the studies say: screen everyone with ID, whether or not they have Down syndrome.
Why it matters
If you serve adults with ID, start dementia screens well before 60.
Watch for memory slips, slower thinking, or behavior changes.
Early detection lets you adjust teaching methods, simplify routines, and train staff sooner.
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02At a glance
03Original abstract
Dementia may be more common in older adults with intellectual disability (ID) than in the general population. The increased risk for Alzheimer's disease in people with Down syndrome (DS) is well established, but much less is known about dementia in adults with ID who do not have DS. We estimated incidence rates from a longitudinal study of dementia in older adults with ID without DS and compared them to general population rates. 222 participants with ID without DS aged 60 years and older were followed up an average of 2.9 years later to identify those who had declined in functional or cognitive abilities. Those who screened positive had a comprehensive assessment for dementia, diagnosed using ICD 10 and DSM IV criteria. 134 participants who did not have dementia at initial assessment were alive and interviewed at follow up; 21 (15.7%) were diagnosed with dementia. Overall incidence rate for those aged ≥ 60 was 54.6/1000 person years (95% CI 34.1-82.3). The highest incidence rate (97.8/1000 person years) was in the age group 70-74. Standardised incidence ratio for those aged ≥ 65 was 4.98 (95% CI 1.62-11.67). Incidence of dementia in older people with intellectual disabilities are up to five times higher than older adults in the general population. Screening may be useful in this population given the high incident rates, particularly as more effective treatments become available. Studies to explore the underlying aetiological factors for dementia associated with intellectual disability could help to identify novel protective and risk factors.
Research in developmental disabilities, 2013 · doi:10.1016/j.ridd.2013.02.021