Behavioral capabilities and mortality risk in adults with and without Down syndrome.

Among adults with mental retardation, mortality rates for those with Down syndrome are higher than for those without Down syndrome. We studied age-related changes in functioning and their relation to subsequent mortality in adults with mental retardation. Among people without Down syndrome, recent loss of basic skills was associated with substantially elevated mortality rates. This was not so in the Down syndrome group, however. Adults with Down syndrome tended to experience regression in adaptive behavior earlier than did those without Down syndrome. Incidence rates in the two groups diverged subsequent to age 40. Adults without Down syndrome, however, did also tend to regress when older.