Protective Association Of Physical Activity By Domain For Major Depressive Disorder: 1999-2004 NHANES

Leisure-time physical activity (LTPA), including structured exercise, has consistently been associated with reduced risk and symptomatology of depression. However, previous studies have neglected to examine the potential protective associations of physical activity (PA) from other domains (i.e., transportational and domestic PA) related to the risk of depression. PURPOSE: The purpose of this study was to simultaneously examine the potential protective associations of three domains of PA (transportation, domestic, and leisure-time) with major depressive disorder (MDD) among young US adults. METHODS: The sample for this study comprised a sub-sample of young adults, 20-39 years of age (N=2,217), who completed a computer-administered MDD diagnostic survey within the 1999-2004 National Health and Nutrition Examination Survey (NHANES). In addition, each respondent completed a comprehensive PA interview assessing the type, frequency, and duration of moderate/vigorous (intensity) PA in the past 30 days specific to the transportation, domestic, and leisure-time domains. These PA measures were recoded to formulate an average weekly frequency and duration value, allowing respondents to be classified into three categories specific to the ACSM/AHA PA recommendation (1=meets rec; 2=some, but insufficient PA; 3=no PA) for each domain and total PA. All age-adjusted analysis was conducted using SUDAAN statistical software. RESULTS: Nationally, the prevalence of MDD was 7.8% (SE=0.81) among young adults. Specific to PA domain, the MDD prevalence was lower among those meeting the PA recommendation compared to who were inactive (leisure: 5.7% vs. 9.3%; transportation: 6.8% vs. 7.3%; domestic: 6.05 vs. 8.3%, respectively). After controlling for demographic covariates, including all PA domains, the only significant risk reduction was found in the leisure PA domain (OR=0.40; 95% CI=0.22-0.72) and total PA (OR=0.43; 95% CI=0.25-0.76). CONCLUSION: The protective associations of PA with depression appear to be restricted to only LTPA. Perhaps LT PA provides a unique mix of biological, psychological, and social mechanisms that are not inherent within transportation or domestic PA. Also, vigorous intensity PA, captured in the leisure-time domain, might provide the necessary dose to reduce risk.