Depression and the onset of dementia in adults with mental retardation.

The relation between dementia and depression in 61 adults with Down syndrome or 43 adults with mental retardation due to other causes was examined. Age-matched participants, ranging in age from 20 to 60 years, received a neuropsychological battery to assess declines in functioning and caregiver report measures to assess adaptive behavior and depression. Eight adults with Down syndrome had both depression and declines in functioning. No adults with mental retardation due to other causes had declines. Greater severity of depression was related to lower MA, poorer memory, and lower adaptive functioning in adults with Down syndrome only. Results suggest that dementia and depression are associated in Down syndrome but not in mental retardation due to other causes.