Adequate physical activity reduces the risk of depression associated with stressful life events: Evidence from the newlywed population

Background: Epidemiological studies suggest that stressful life events (SLEs) and physical activity are associated with depression. However, very few studies have explored their interaction effects, especially in the newlywed population. This study aimed to estimate the independent and interaction effect of SLEs and physical activity on depression in newlyweds. Methods A total of 60,315 newlywed people from the Reproductive Health of Childbearing Couples-Anhui Cohort were included in the study. A 12-item checklist of stressful events was used to assess SLEs during the past six months. The International Physical Activity Questionnaire Short Form was used to evaluate physical activity in the past week. The Patient Health Questionnaire-9 was used to assess depression in the past two weeks. Generalized linear regression models were constructed to evaluate the independent and interaction effect of SLEs and physical activity on depressive scores. Results Of the 60,315 newlywed people, 70.6% had experienced at least one SLE during the past six months; 48.4%, 39.3%, and 12.3% of participants reported low, moderate, and high physical activity levels, respectively. After adjusting for covariates, more SLEs (1 ≤ SLEs ≤ 2: β  = 0.978, 95% CI: 0.877–1.079; SLEs ≥ 3: β  = 2.582, 95% CI: 2.485–2.670) and higher (moderate: β = -0.461, 95% CI: -0.561 ~ -0.361; high: β = -0.641, 95% CI: -0.786 ~ -0.495) physical activity were associated with increased and reduced depression scores, respectively. Significant interaction effects of SLEs and physical activity on depressive scores were observed ( P for interaction < 0.001). Specifically, SLEs were more strongly associated with depressive scores in the low physical activity group (1 ≤ SLEs ≤ 2: β  = 0.978, 95% CI: 0.877–1.079; SLEs ≥ 3: β  = 2.582, 95% CI: 2.487–2.678) than that in the moderate (1 ≤ SLEs ≤ 2: β  = 0.747, 95% CI: 0.654–0.841; SLEs ≥ 3: β  = 2.104, 95% CI: 2.014–2.195) or high (1 ≤ SLEs ≤ 2: β  = 0.827, 95% CI: 0.668–0.987; 3 ≤ SLEs: β  = 2.168, 95% CI: 2.015–2.321) physical activity groups. Conclusions The findings indicate that adequate physical activity is a potential precautionary buffer against depression associated with SLEs in the newlywed population. Strategies to improve the level of regular physical activity may be adopted by the government to promote the overall well-being of the country.