To study factors associated with different mood disorders in old age,
researchers need clear and meaningful definitions. ''Major depression'
' is too broad and heterogeneous a category, and the boundaries of ''d
ysthymia'' are ill-defined, yet epidemiologic studies have focused on
these disorders. Depressions in old age are commonly associated with m
edical conditions; prevalence rates of depression in cases of stroke,
Parkinson's disease, dementia, and disabilities (all much commoner in
old age) range upward from about 20%. Depressions are attributed to bo
th psychological and biological reactions. Mania, too, can be precipit
ated by cerebral and other medical factors. The proportion of psychiat
ric inpatients who have depressions with melancholic and/or psychotic
features is higher among elderly subjects, and this has been linked wi
th white matter lesions and other brain changes that become commoner i
n old age. The prognostic relevance of these brain changes, and implic
ations for treatment of mood disorders, require clarification. (C) 199
7 Wiley-Liss, Inc.