Kind courtesy of Rosemarie Speidel ("speidel" <speidel@...>)
comes the following:

PHYSICAL ACTIVITY REDUCES THE RISK OF SUBSEQUENT DEPRESSION FOR OLDER ADULTS
This study concluded that elderly individuals who remained active were less
likely to be depressed or to become depressed. The researchers tracked 1,947
people, ages 50 to 95, over a period of five years, utilizing an eight-point
scale to measure the amount of exercise they received. Each one-point
increase, the investigators ascertained, reduced the risk of being depressed
by 10%, and of becoming depressed by 17%. The improvements were clear even
after adjustments were made for age, sex, ethnicity, financial strain,
chronic conditions, disability, body mass index (BMI), smoking, alcohol
consumption, and social relations.
American Journal of Epidemiology 2002;156:328-34