Objectives. To prospectively examine whether changes in smoking, heavy alcohol consumption, sedentary lifestyle, and obesity are associated with the risk of erectile dysfunction.

Methods. Data were collected as part of a cohort study of a random sample of men 40 to 70 years old, selected from street listings in the Boston Metropolitan Area, Massachusetts. In-home interviews were completed by 1709 men at baseline in 1987 to 1989 and 1156 men at follow-up in 1995 to 1997 (average follow-up 8.8 years). Analyses included 593 men without erectile dysfunction at baseline, who were free of prostate cancer, and had not been treated for heart disease or diabetes. The incidence of moderate to complete erectile dysfunction was determined by discriminant analysis of responses to a self-administered sexual function questionnaire.

Results. Obesity status was associated with erectile dysfunction (P = 0.006), with baseline obesity predicting a higher risk regardless of follow-up weight loss. Physical activity status was associated with erectile dysfunction (P = 0.01), with the highest risk among men who remained sedentary and the lowest among those who remained active or initiated physical activity. Changes in smoking and alcohol consumption were not associated with the incidence of erectile dysfunction (P >0.3).

Conclusions. Midlife changes may be too late to reverse the effects of smoking, obesity, and alcohol consumption on erectile dysfunction. In contrast, physical activity may reduce the risk of erectile dysfunction even if initiated in midlife. Early adoption of healthy lifestyles may be the best approach to reducing the burden of erectile dysfunction on the health and well-being of older men.