Unhealthy lifestyles do not mediate the relationship between socioeconomic status and incident depressive symptoms: The health ABC study

Background: The relationship between low socioeconomic status (SES) and depressive symptoms is well described, also in older persons. Although studies have found associations between low SES and unhealthy lifestyle factors, and between unhealthy lifestyle factors and depressive symptoms, not much is known about unhealthy lifestyles as a potential explanation of socioeconomic differences in depressive symptoms in older persons. Methods: To study the independent pathways between SES (education, income, perceived income, and financial assets), lifestyle factors (smoking, alcohol use, body mass index, and physical activity), and incident depressive symptoms (Center for Epidemiologic Studies-Depression [CES-D 10] and reported use of antidepressant medication), we used 9 years of follow-up data (1997-2007) from 2,694 American black and white participants aged 70-79 years from the Health, Aging, and Body Composition (Health ABC) study. At baseline, 12.1% of the study population showed prevalent depressive symptoms, use of antidepressant medication, or treatment of depression in the 5 years prior to baseline. These persons were excluded from the analyses. Results: Over a period of 9 years time, 860 participants (31.9%) developed depressive symptoms. Adjusted hazard ratios for incident depressive symptoms were higher in participants from lower SES groups compared with the highest SES group. The strongest relationships were found for black men. Although unhealthy lifestyle factors were consistently associated with low SES, they were weakly related to incident depressive symptoms. Lifestyle factors did not significantly reduce hazard ratios for depressive symptoms by SES. Conclusion: In generally healthy persons aged 70-79 years, lifestyle factors do not explain the relationship between SES and depressive symptoms.