266 MINIMALLY-EFFECTIVE PHYSICAL ACTIVITY DOSE FOR DEPRESSION AMONG OLDER ADULTS: PRELIMINARY FINDINGS FROM THE IRISH LONGITUDINAL STUDY ON AGEING

Abstract

Abstract Background Among older adults, depression is associated with increased risk of lower physical, social, and cognitive function. Physical Activity (PA) has been associated with lower odds of depression; however, the minimally sufficient dose for protection is unknown. Herein, we quantified the association between different PA doses and depressive symptoms and status among older adults across 10 years (waves 1-5) as part of The Irish Longitudinal Study on Ageing. Methods PA was measured at each wave using the short-form International Physical Activity Questionnaire (IPAQ-SF). Five dose categories (0, 1-<600, 600-<1,200, 1,200-<2,400 and ≥2,400 MET.min.week-1) were examined. At all waves, depressive symptoms were assessed using the Center for Epidemiological Studies Depression Scale short form (CES-D) and a score of ≥16 was used to define depression. From Waves 2-5, the Composite International Diagnostic Interview quantified diagnosis of a Major Depressive Episode during the past 12 months, or depression status. Poisson regression quantified associations between PA dose and depressive symptoms and status across time, adjusted for age, health/lifestyle variables and antidepressant medication. Results Among 4,017 participants, depression status changed from 8.2% at wave 1 to 12.2% at wave 5. The minimal PA dose associated with lower depressive symptoms was 1-<600 MET.min.week-1 (coefficient = –0.06; 95%CI: –0.10, –0.02; p≤0.003). A dose of 600-<1,200 MET.min.week-1 was significantly associated with lower odds of depression status (OR = 0.66; 95%CI: 0.50, 0.87; p≤0.004). Other positive predictors associated with lower odds of depression included greater age, higher education status, and sufficient vitamin D status. Conclusion Present findings suggest that even low physical activity doses appear protective against depressive symptoms among older adults. Moderate PA dose, consistent with WHO recommendations, was protective against major depression over a 10-year period among older adults. However, individuals with chronic conditions may have different PA dose requirements, which should be further investigated.