Objectives: Cross sectional data of National Health and Nutrition Examination Survey (NHANES 1999-2012) were analyzed to examine inverse associations between depression and exercise. Retrospective case-control study was used to quantify anaerobic “muscle strengthening activity” associated with depression severity, while controlling for aerobic activity. Anti-depressive benefits associated with “moderate intensity activity”, and interactions with prolonged statin treatment were studied.
Methods: Depression was assessed using a validated “Patient Health Questionnaire (PHQ9)” survey with depression scores in (0-27) range. PHQ9>=10 is a dichotomous indicator of depression. Gender-stratified logistic regression was used to estimate odds ratios (OR) of anaerobic “muscle strengthening activity” associated with depression, while controlling aerobic activity. Multinomial logistic regression was used to estimate OR of “muscle strengthening activity” associated with these severity levels of depression: mild (5–9), dysthymia (10–14), moderate (15–19), major-depression (20–27), in comparison with reference (0-4). Models adjusted for aerobic activity energy expenditure, age, BMI, and medical conditions. Subgroups of adults diagnosed with or without osteoarthritis, rheumatoid arthritis, cancer (of breast, cervix, uterine, prostate, colon rectum, non-melanoma, melanoma, skin), cardiovascular disease (congestive heart failure, coronary heart disease, angina pectoris, myocardial infarction, stroke), or metabolic syndrome, were examined separately. Similar analyses were conducted for “moderate intensity activity” and depression. Time series logistic models computed OR of exercise and depression with increasing duration of lipophilic/hydrophilic statin treatment.
Results: Among 3935 women and 3419 men participating in NHANES during 1999-2006, women had a higher prevalence of depression than men (8.8% versus 5.7%) and a lower prevalence of muscle strengthening activity (26% versus 41%). Muscle strengthening activity was inversely associated with depression (PHQ9>=10) in women under 50 (OR=0.58; 95% CI=0.41-0.82), all women (OR=0.59; 0.43-0.80), men under 50 (OR=0.79; 0.54-1.10), and all men (OR=0.66; 0.47-0.93), while adjusting for aerobic activity. In adults with arthritis, cancer, metabolic syndrome, or CVD, statistically significant inverse trends existed between muscle strengthening activity and depression severity with adjustment for aerobic exercise. Among 5843 women and 4617 men participating in NHANES during 1999-2012, “moderate intensity activity” was inversely associated with depression (PHQ9>=10) in women under 50 (OR=0.62; 0.49-0.78), men under 50 (OR=0.54; 0.38-0.76), all women (OR=0.58; 0.49-0.68), and all men (OR=0.47; 0.37-0.58). Moderate intensity activity was inversely associated with depression severity in women (mild, dysthymia, moderate, major-depression: OR=0.80, 0.63, 0.51, 0.30, respectively) and in men (mild, dysthymia, merged moderate-major-depression: OR=0.71, 0.44, 0.43, respectively). Prolonged lipophilic statin treatment increased the OR of depression associated with exercise among women diagnosed with CVD (OR from 0.6 to 0.91; beyond >=550 days), and among women without any CVD (from 0.69 to 0.89; beyond >=800 days). However, prolonged hydrophilic statin did not impact the OR trend. Men had similar results.
Conclusions: Anaerobic muscle strengthening activity was inversely and independently associated with depression among healthy US adults, and among those with CVD, cancer, metabolic syndrome or arthritis (NHANES 1999-2006). Severity of depression was also inversely related to a more general measure of exercise, “moderate intensity physical activity” (NHANES 1999-2012). Long term lipophilic statin treatment diminished the inverse association of exercise and depression.