Mental health literacy, folic acid and vitamin B12, and physical activity for the prevention of depression in older adults: randomised controlled trial.

BACKGROUND Few randomised controlled trials (RCTs) have examined potential preventive agents in high-risk community populations. AIMS To determine whether a mental health literacy intervention, the promotion of physical activity, or folic acid plus vitamin B(12) reduce depression symptoms in community-dwelling older adults with elevated psychological distress. METHOD An RCT with a completely crossed 2 x 2 x 2 factorial design: (400 mcg/d folic acid + 100 mcg/d vitamin B(12) v. placebo)x(physical activity v. nutrition promotion control)x(mental health literacy v. pain information control). The initial target sample size was 2000; however, only 909 adults (60-74 years) met the study criteria. Interventions were delivered by mail with telephone calls. The main outcome was depressive symptoms on the Patient Health Questionnaire (PHQ-9) at 6 weeks, 6, 12 and 24 months. The Clinicaltrials.gov registration number is NCT00214682. RESULTS The drop-out rate was low (13.5%) from randomisation to 24-month assessment. Neither folic acid + B(12) (F(3,856) = 0.83, P = 0.476) nor physical activity (F(3,856) = 1.65, P = 0.177) reduced depressive symptoms at any time point. At 6 weeks, depressive symptoms were lower for the mental health literacy intervention compared with its control condition (t(895) = 2.04, P = 0.042). CONCLUSIONS Mental health literacy had a transient effect on depressive symptoms. Other than this, none of the interventions significantly reduced symptoms relative to their comparator at 6 weeks or subsequently. Neither folic acid plus B(12) nor physical activity were effective in reducing depressive symptoms.