Organic brain syndrome and aging. A six-year follow-up of surviving twins.

The development of organic brain syndrome (OBS) was studied in a small group of survivors from a longitudinal investigation of aging twins. At the time of initial evaluation, the frequency of moderate to severe OBS was 25%. Among the 22 survivors who had a second psychiatric evaluation after approximately six years, the corrected rate for the development of OBS among those without it at the initial examination was 16%. Thus, the vast majority of those diagnosed as being without OBS at about the age of 80 years remained asymptomatic in subsequent years, supporting the view that OBS is not a necessary concomitant of old age, but the result of disease for which prevention and cure should be sought. Persons originally diagnosed as having OBS had the higher mortality, an observation in accord with prior reports in the literature. In the present study, the increased mortality was related to the severity of OBS but apparently independent of coexisting physical illness, again supporting the argument that OBS represents pathological as distinct from physiological aging.