J. Snowdon et F. Lane, THE BOTANY SURVEY - A LONGITUDINAL-STUDY OF DEPRESSION AND COGNITIVE IMPAIRMENT IN AN ELDERLY POPULATION, International journal of geriatric psychiatry, 10(5), 1995, pp. 349-358
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.