The effect of age and residential placement on adaptive behaviour of adults with Down's syndrome.

Through widespread enquiry, the population of adults with Down's syndrome (aged over 18 years) in Leicestershire was estimated at 376. For 315 of these (83.8%), the immediate carer was invited to complete the Adaptive Behavior Scale (ABS). Completed ABS assessments were obtained on 81.9% of the adult population with Down's syndrome in the county. Additional information concerning residential history was obtained. When the sample was divided into five cohorts on the basis of age when the ABS assessment took place, an exponential decline in ability was observed. Deterioration in most domains of the ABS achieved statistical significance in the cohort aged 50-59, and in all domains in those aged 60 and over. The deterioration in global skills in older cohorts was attributed to ageing (and thereby probably Alzheimer's disease). Institutional placement was associated with low scores in younger groups only.