Sedentary behavior as a potential risk factor for depression among 70-year-olds.

BACKGROUND: Sedentary behavior has previously been associated with the risk of depression. In addition, older adults have been proven to be more sedentary and more depressed than other age groups. However, studies using objective measures of sedentary behavior and taking physical activity into account are lacking. Thus, the purpose of this population-based study was to examine how total sedentary time and length of sedentary bouts were associated with the risk of depression among 70-year-olds. METHODS: The present study used data from the Healthy Ageing Initiative (n = 3,633), an ongoing cross-sectional research project in Umeå, Sweden. Sedentary behavior was measured objectively with the ActiGraph GT3X+ accelerometer, and depression was measured with the Geriatric Depression Scale. Several covariates, including physical activity, were included in logistic regression analyses. RESULTS: Results from two hierarchical logistic regression models showed that a greater percentage of the day spent sedentary [odds ratio (OR) = 1.031, p = 0.010] and longer average length of sedentary bouts (OR = 1.116, p = 0.045) increased the risk of depression. LIMITATIONS: Limitations include of possible underrepresentation of severely depressed participants, and possible observer effects. CONCLUSIONS: The present study verified the relationship between sedentary behavior and depression and provides new information about the risks associated with increased length of sedentary bouts.  These findings may be important to consider in the development of future recommendations for the prevention of depression among older adults.