Background: Obesity has been associated with increased risk of prevalent depression among young and middle-aged adults, but the association between obesity (and its various measures, including the metabolic syndrome [MetS]) and incident depression has not been examined adequately in the elderly.
Objectives: This study evaluated the association between various measures of obesity and incident depression over a 10-year period in a large cohort of community-based older men.
Methods: The authors recruited 12,216 men aged 65-84 years living in Perth, Australia, between 1996 and 1998, and measured their height, weight, waist and hip circumference, and blood pressure. Participants also completed a questionnaire that included information about the clinical diagnosis and treatment for diabetes, hypertension, and high cholesterol or triglycerides. The authors then used the Western Australian Linked Data System to retrieve information about the following ICD-10 diagnoses between January 1, 1966, and December 31, 2006: depressive episode, recurrent depressive disorder, and dysthymia.
Results: The authors excluded 150 men from these analyses because of prior history of depression or missing data. The mean age of our 12,066 participants was 72 +/- 4 years at the time of recruitment, and they were followed up for an average of 8 +/- 2 years. There were 3,623 deaths during follow-up, and 481 men received the diagnosis of depression. The incidence of depression was 5 per 1,000 person-years. Adjusted Cox proportional hazard models showed that men with body mass index (BMI) > or =30 had a 31% (95% confidence interval [CI] = 5%-64%) increase in the risk of depression compared with that of nonobese men (BMI <30). The association between depression and waist circumference > or =102 cm and waist/hip > or =1 did not reach statistical significance. Men with MetS at the time of recruitment had a 137% (95% CI = 60%-251%) increase in the adjusted risk of incident depression.
Conclusions: Our results indicate that obesity and MetS are associated with an increase in the risk of incident depression among older men. If this association is truly causal, reducing the prevalence of obesity and MetS could potentially lead to a decline in the prevalence and incidence of depression in later life.