Religion, spirituality and depression in prospective studies: A systematic review

Background: Many empirical studies have shown inverse associations between measures of religiousness and spirituality (R/S) and depression. Although the majority of these studies is cross-sectional, a considerable number of prospective studies have also appeared. Methods: The current systematic review offers an overview of the major pattern of associations between the measures of R/S and depression / depressive symptoms in 152 prospective studies (until 2017). Results: With on average two R/S measures per study (excluding measures of religious struggle, treated separately), 49% reported at least one significant association between R/S and better course of depression, 41% showed a non-significant association, and 10% indicated an association with more depression or mixed results. The estimated strength of these associations was modest (d = -0.18). Of the studies that included religious struggle, 59% reported a significant association with more depression (d = + 0.30). Especially among persons identified with psychiatric symptoms, R/S was significantly more often protective (d = -0.37). In younger samples and in samples of patients with medical illness, R/S was less often protective. Studies with more extensive adjustment for confounding variables showed significantly more often associations with less depression. Geographical differences in the findings were not present. Limitations: Given the huge heterogeneity of studies (samples size, duration of follow-up), the current synthesis of evidence is only exploratory. Conclusion: In about half of studies, R/S predicted a significant but modest decrease in depression over time. Further inquiry into bi-directional associations between religious struggle and (clinical) depression over time seems warranted.