3. Methods
Two thousand six hundred thirteen subjects were interviewed with a structured questionnaire by trained interviewers at baseline and at 2 year follow up. Gender, age, educational level, developmental factor, chronic medical conditions and cognitive impairment were collected at baseline. Marital status, social support network, alcohol consumption,self-rated health status and life events experienced in the past year were assessed at follow up. The uses of antidepressant medication were recorded at both visits.