Age and depression: unique and shared effects.

The degree to which psychosocial variables associated with depression were also associated with age was examined in 3 samples of community residents 50 years of age or older (N = 4,617). Most of the expected concomitants of depression were found. With only a few exceptions, age was not correlated with depression-related psychosocial variables. Rather, age was most strongly associated with levels in neuropsychological and psychophysiological functioning. In addition, the magnitudes of the correlations in women compared with men and in young-old age groups compared with old-age groups were examined. A number of significant differences emerged, and their implications for theories of depression are noted.