THE BOTANY SURVEY - A LONGITUDINAL-STUDY OF DEPRESSION AND COGNITIVE IMPAIRMENT IN AN ELDERLY POPULATION

An 8-year-long longitudinal study of elderly people in Botany (Sydney) has provided data on the prevalence, incidence and outcome of cogniti ve impairment and depression in this population. In 1985, a random sam ple of 146 persons aged 65 years or more, living in their own homes, w ere assessed using the Brief Assessment Schedule, depression ratings a nd cognitive tests. Follow-up interviews were conducted after 2, 4, 6 and 8 years. Data from separate hostel and nursing home studies were u sed when estimating prevalence rates. The estimated prevalence and ann ual incidence of definite dementia in Botany were, respectively, 14% ( 3.5% severe) and 2.5%. Among elderly people living at home the prevale nce of definite dementia was 11%; 23% of our community sample suffered dementia during the 8 years. The prevalence and minimum annual incide nce of depressive disorders were, respectively, 12.5% and 2.0%. Among those living at home the prevalence was 12.3%. Dementia was associated with a high mortality rate, but the apparently increased mortality of depressed subjects did not reach significance, probably because numbe rs were relatively small; a high proportion of the deceased had comorb id cognitive impairment. Some depressions eventually remitted.