BACKGROUND: The life expectancy of people with mental retardation is shorter than that of the general population. Exact estimates of the length of survival for mentally retarded persons at especially high risk are not available, however. METHODS: We collected data on mortality and other factors for 99,543 persons with developmental disabilities, including mental retardation, who received services from the California Department of Developmental Services between March 1984 and October 1987. Three subgroups were selected on the basis of the four characteristics identified in previous studies as the best predictors of mortality among mentally retarded people (deficits in cognitive function, limitations on mobility, incontinence, and inability to eat without assistance). In all three subgroups, the subjects had severe deficits in cognitive function and were incontinent; the subjects in subgroup 1 (n = 1550) were immobile and required tube feeding; those in subgroup 2 (n = 4513) were immobile but could eat with assistance; those in subgroup 3 (n = 997) were mobile (but not ambulatory) and could eat with assistance. Life tables were generated for each of the three subgroups. RESULTS: Immobile subjects were found to have a much shorter life expectancy than those who could move about. Those who also required tube feeding (subgroup 1) had a very short life expectancy (i.e., four to five additional years). Those who could eat if fed by others (subgroup 2) had an average life expectancy of approximately eight additional years. In contrast, those who were mobile though not ambulatory (subgroup 3) had a life expectancy of about 23 additional years. CONCLUSIONS: Severe mental retardation is associated with a decrease in life expectancy, particularly for those who were immobile.
Eyman et al. (1990) studied this question.