Associations between unhealthy lifestyle and depression: Cross-sectional results from the Spanish National Health Survey

Introduction: Depression usually worsens lifestyle habits, but previous evidence also suggests that an Unhealthy Lifestyle (UL) increases the risk of depression. Many studies have analyzed the association between lifestyle and depression in several nationally representative samples, but none have done so in the Spanish adult population. Our aim was to examine the associations between UL habits and depression in Spain. Materials and Methods: Analysis of cross-sectional data from the latest National Health Survey published in 2018 (N=23,089). Data on depression and 4 lifestyle factors (diet, physical exercise, smoking, and alcohol consumption) were used. These factors were combined into an UL index ranging from 0 (healthiest lifestyle) to 4 (unhealthiest lifestyle). The prevalence of depression at different levels of the UL index, and the association between depression and both the cumulative UL index and the 4 UL factors was analyzed using parametric and non-parametric tests. Results: Sedentarism was the most prevalent UL factor, followed by unhealthy diet, smoking and alcohol consumption. Having ≥1 UL factors was associated with a higher prevalence of depression compared to having 0 UL factors (2.5% vs. ≥5.0%), regardless of the cumulative number UL factors. Being physically inactive (OR=1.6) and a smoker (OR=1.3) were positively associated with depression. Being a high-risk wine drinker (OR=0.26) was negatively associated with depression. Dietary intake was not significant. Conclusions: The prevalence of depression changes depending on several modifiable lifestyle factors. Policy makers should therefore spare no resources in promoting strategies to encourage healthy lifestyles and prevent the acquisition of UL habits.