Stability and change in cognitive ability over the life span: a comparison of populations with and without Down's syndrome.
Expect verbal skills to fall faster and performance skills to hold up better in aging clients with ID versus typical aging trends.
01Research in Context
What this study did
Cockram (2005) pooled 11 earlier studies on how thinking skills change as people with intellectual disability grow old. The review focused on adults with and without Down syndrome. It looked for patterns in verbal, memory, and problem-solving scores across the life span.
What they found
Older adults with ID showed a flip-flop pattern. Verbal scores dropped faster than usual. Hands-on puzzle and picture tasks held up better than expected. This is the opposite of typical aging, where verbal skills usually stay strong and visual tasks fade first.
How this fits with other research
Prasher et al. (1995) and Davison et al. (1995) saw steep drops in planning, memory, and daily skills in the same age group. Their single studies match the broad decline the review reports. Vakil et al. (2012) extended the story to movement. They found balance and strength also fall faster in older adults with Down syndrome, adding motor loss to the cognitive picture. Together these papers build a timeline: expect earlier and wider decline in multiple domains, not just thinking.
Why it matters
When you plan skill-building goals for aging clients with ID, flip the usual script. Shore up verbal routines like phone use or story recall early. Lean on visual cues, photos, and hands-on tasks that stay stronger longer. Track both language and motor changes each quarter so you can adjust programs before losses pile up.
Want CEUs on This Topic?
The ABA Clubhouse has 60+ free CEUs — live every Wednesday. Ethics, supervision & clinical topics.
Join Free →Add a quick verbal fluency probe and a visual puzzle task to your next session; note which score is higher to set the right cueing style.
02At a glance
03Original abstract
BACKGROUND: Longitudinal studies show that in the general population IQ declines with age: early and rapidly in the case of performance IQ, later and more slowly in the case of verbal IQ. These populations have not apparently included people with intellectual disabilities (ID). METHOD: A literature search identified 11 studies, some cross-sectional and others longitudinal, which provided data on a variety of verbal and performance tests, over periods from 3 to 19 years, on older people with ID. Following statistical advice the results from the different tests were converted into the equivalent of, for verbal scores, British Picture Vocabulary Scale, and for performance scores, Leiter International Performance Scale, raw scores. Percentage change between earlier and later scores was then calculated. RESULTS: With one exception the studies considered tend to show verbal ability declining relatively more, and performance ability declining relatively less, than has been shown to occur in the general population. Potential confounding factors, such as population attrition, cohort effects, etc., are thought not to have affected these results. CONCLUSIONS: The pattern of change with age in verbal and performance ability appears different in people with ID from that seen in the general population. Some possible reasons for this difference are discussed.
Journal of intellectual disability research : JIDR, 2005 · doi:10.1111/j.1365-2788.2005.00735.x