Depression is the second leading cause of disability in the world; isolating risk and protective factors can aid in reducing the prevalence of depression worldwide. One factor that has been reliably shown to increase the risk of major depressive disorder (MDD) is having one or more depressed parents (1). Curiously, some offspring with familial depression do not develop MDD, whereas others with no family history of depression develop it. Thus, there must be other predisposing factors in addition to genetic ones.
One variable that has been recently explored as a protective factor is religiosity, spirituality. (For simplicity, in this article I will not differentiate between religiosity and spirituality.) It is defined in some studies as believing in the importance of religion/spirituality and engaging in religious behaviors. This dimension is an influential factor that shapes the practicing person’s cognitive processes. Many studies have demonstrated the positive effects of religiosity for depression (2, 3).
A longitudinal prospective study analyzed the prevalence of depression in 114 offspring of depressed and non-depressed parents at 10-year and 20-year follow-up assessments. This was a part of a three-generation study that started in 1982. In addition to measuring mood disorders, they also measured the personal importance of religion/spirituality and the frequency of attendance at religious services. The rate of depression in the high-risk group (at least one parent with depression) was twice as those with non-depressed parents. Across both groups, offspring who reported at the first assessment that religion/spirituality was highly important had about one-fourth of the risk of MDD at the second assessment (10 years later). Interestingly, the group who benefited the most from religiosity was the group at high risk for depression—those who had a depressed parent. In this high-risk group, those who reported that religion was of high importance had about one-tenth the risk of experiencing an MDD ten years later compared to high-risk participants who did not believe in the importance of religiosity (4). The most pronounced effects for religiosity were for the recurrence of depression than for onset. These results are not anomalous. A meta-analysis of 147 studies (N= 98,975) showed an inverse relationship between depression symptoms and religiosity (5).
But how? Depression is a brain disorder, so exacerbating and protective factors have to show changes in brain morphology, activations, and connections. Does religiosity do that? A recent review of a large body of studies strongly suggests that spiritual practices may be associated with changes in the brain, including increasing serotonin levels (6). But, can religiosity specifically "fix" depression-related brain atrophy? The above mentioned longitudinal study found large expanses of cortical thinning in many regions in the brains of high-risk adult offspring compared with the low-risk group. Can a strong belief in the importance of religiosity/spirituality rescue the cortical thinning in the high-risk group and thus reduce the recurrence of depression?
The researchers studied these offspring for an additional five years. They examined the relationship between cortical thinning and religiosity. First, participants who valued religion had thicker cortices regardless of family risk—high or low risk. Second, the effects were stronger and more extensive for the high-risk than in the low-risk group (7).
In a more recent investigation on this three-generation study, further brain differences were reported (8). They demonstrated that religiosity can have significant effects at the microstructural and anatomical levels in the brain. The researchers utilized diffusion tensor imaging to study white matter (connections) in the brains of high- and low-risk individuals as a function of how they rate the importance of religiosity. One notable conclusion from this study is that valuing religion minimizes the brain differences between high- and low-risk groups. I.e., the brains of those at high risk for depression because it runs in their families start to look similar to the brains of those at low risk for MDD.
In sum, it seems like religiosity/spirituality may confer resilience to the development/recurrence of depressive episodes in individuals in general and in ones with high risk in specific. This resiliency is maybe a result of the relationship between religiosity and a thicker cortex, efficient macro-structure and connections, or better blood flow to brain areas implicated in depression (9). Scientists are still working to discover more protective factors.
(1) Weissman, M. M., Berry, O. O., Warner, V., Gameroff, M. J., Skipper, J., Talati, A., ... Wickramaratne, P. (2016). A 30 -year study of 3 genera‐tions at high risk and lowrisk for depression. JAMA Psychiatry, 73(9), 970–977. https://doi.org/10.1001/jamapsychiatry. 2016.
(2) Fox, K. C., Nijeboer, S., Dixon, M. L., Floman, J. L., Ellamil, M., Rumak, S. P., ... Christoff, K. (2014). Is meditation associated with altered brainstructure? A systematic review and meta‐analysis of morphometric neuroimaging in meditation practitioners. Neuroscience & Biobehavioral Reviews, 43, 48–73. https://doi.org/10.1016/j.neubiorev.2014.03.016
(3) Harris, S., Kaplan, J. T., Curiel, A., Bookheimer, S. Y., Iacoboni, M., & Cohen, M. S. (2009). The neural correlates of religious and nonreli‐ gious belief. PLoS ONE, 4(10).
(4) Miller L, Wickramaratne P, Gameroff MJ, Sage M, Tenke CE, Weissman MM. Religiosity and major depression in adults at high risk: a ten-year prospective study. Am J Psychiatry. 2012;169(1):89-94.
(5) Smith TB, McCullough ME, Poll J: Religiousness and depression: evidence for a main effect and the moderating influence of stressful life events. Psychol Bull 2003; 129:614–636
(6) Newberg A: Transformation of brain structure and spiritual experience, in Oxford University Press Handbook of Psychology and Spirituality. Edited by Miller L. New York, Oxford University Press, 2011.
(7) Miller L, Bansal R, Wickramaratne P, et al. Neuroanatomical Correlates of Religiosity and Spirituality: A Study in Adults at High and Low Familial Risk for Depression. JAMA Psychiatry. 2014;71(2):128–135. doi:10.1001/jamapsychiatry.2013.3067
(8) Li X, Weissman M, Talati A, et al. A diffusion tensor imaging study of brain microstructural changes related to religion and spirituality in families at high risk for depression. Brain Behav. 2019.
(9) Newberg A,Pourdehnad M,Alavi A,d’Aquili EG. Cerebral blood flow during meditative prayer: preliminary findings and methodological issues. Percept Mot Skills. 2003;97(2):625-630.