Indoor Environmental Determinants of Depression: A New Approach to Understanding Mental Health

Background and Objectives: Depression has emerged in recent years as a significant global health issue, drawing considerable research interest and attention. The development of depression could be impacted by a range of environmental factors. Aim: To investigate the relationship between depressive symptoms and various indoor environmental factors, such as microclimate, odors, mold, and room ventilation, in association with some sociodemographic and lifestyle factors. Materials and Methods: This epidemiological health survey of the study “Chronic diseases and their risk factors in the adult population” was performed during 2023–2024 in Kaunas city (Lithuania) following the methodology of the WHO MONICA study. A random sample of Kaunas inhabitants aged 25–69 years, stratified by sex and age, was randomly selected from the Lithuanian population register. The 3426 individuals were screened. The associations of various indoor environmental factors with depressive symptoms were investigated using binary logistic regression analysis. Results: Depressive symptoms were associated with sociodemographic, lifestyle, and indoor environmental factors. Poor microclimate conditions, unpleasant household odors, mold exposure, and insufficient room ventilation were associated with increased odds of depressive symptoms. The significance of these associations varied across sex, age, marital status, socioeconomic status, and physical activity of responders. Additional multivariable logistic regression analyses, including interaction terms between each indoor environmental factor and the stratification variables (sex, age groups, marital status, family economic situation, and physical activity), were performed. Significant interaction was found only between family status and room ventilation (p = 0.007). This indicates that the association between ventilation and depressive symptoms differed by family status. Conclusions: This study contributes to the cross-disciplinary understanding of the role of indoor environmental quality, sociodemographic, and lifestyle factors in the development of depression, adding to the evidence on the role of other factors in depression inequalities.