BLOG: The home and epigenome
Published: 25 Aug, 2023

The blog discusses the connection between housing quality and mental health, highlighting the role of epigenetics in understanding this association and sharing preliminary findings that suggest DNA methylation mediates the link between poor housing quality and depressive symptoms in mothers.

A link between housing quality and mental health has been consistently evidenced (Evans et al., 2003; Singh et al., 2019), demonstrating the critical need for improving housing quality. However, unlike other mental health risk factors such as trauma, the biological correlates underlying this association remain unclear. Investigating biological correlates is not only important for raising awareness and understanding of the importance of housing quality for both physical and mental health, but also advancing our understanding of the role of epigenetics in the interplay between our physical environment and mental health. Epigenetics is simply the study of biological processes, such as DNA methylation, which are influenced by both genetics and environmental exposures and, in turn, can alter gene activity.

Before exploring the biological underpinnings of associations between housing quality and mental health, it is, of course, critical to assess complex social underpinnings. For example, an individual’s risk of depressive symptoms is increased if their parent experienced depressive symptoms, not only through inherited genetics, but also through observation of parents’ behaviour via social inheritance (Brophy et al., 2021). Similarly, poor housing quality is also associated with a lower socioeconomic status (SES), another risk factor for poor mental health (Dunn et al., 2006). Hence, we included these variables as controls in our models.

Why did we want to know about the biological processes involved in the link between housing quality and mental health?

First, a better understanding of the underlying biology can advance our understanding of gene-environment interactions in the context of the physically built environment, so far a barely understood process. Whilst research has focussed on understanding gene-environment interactions in the context of the social environment (McGowan & Szyf, 2010), the physically built environment has been more neglected. Although these environments do not operate in isolation, neglecting the physically built environment in gene-environment studies has limited our understanding of the importance of the physically built environment for health.

Second, complex traits such as mental health (e.g., depressive symptoms) arise from the interplay of both environmental and genetic factors (Lesch, 2004). DNA methylation captures both genetic and environmental variance which otherwise may be missed. Hence, whilst biological mechanisms alone are unlikely to fully explain complex associations between housing quality and mental health, as explained above when referring to social inheritance, they may add an extra layer of understanding to these associations.

At the University of Bath, we are working on a project with collaborators at Harvard Medical School, currently investigating whether DNA methylation mediates associations between poor housing quality and depressive symptoms in a sample of around 600 mothers living within the Avon area in the UK. We found that DNA methylation did indeed mediate the association between poor housing quality and depressive symptoms in these mothers, but only in early and not late adulthood (Sanders et al., 2023). These results demonstrate the importance of housing quality in depression, but also suggest housing quality’s role may differ across the lifespan.

To further understand these nuances and explore to which degree DNA methylation has an age-dependent role, we are currently working on a similar investigation focussing on children and adolescents.

To conclude, housing and epigenetic studies provide a nuanced method of assessing the role of housing quality in mental health. Our preliminary findings highlight the need for further investigations to understand the complexity of how epigenetic processes may be involved in these complex but critical associations.

References 

Brophy, S., Todd, C., Rahman, M. A., Kennedy, N., & Rice, F. (2021). Timing of parental depression on risk of child depression and poor educational outcomes: A population based routine data cohort study from Born in Wales, UK. PloS one16(11), e0258966.

Dunn, J. R., Hayes, M. V., Hulchanski, J. D., Hwang, S. W., & Potvin, L. (2006). Housing as a socio-economic determinant of health: Findings of a national needs, gaps and opportunities assessment. Canadian Journal of Public Health= Revue Canadienne de Sante Publique97(Suppl 3), S12.

Evans, G. W., Wells, N. M., & Moch, A. (2003). Housing and mental health: a review of the evidence and a methodological and conceptual critique. Journal of social issues, 59(3), 475-500.

Lesch, K. P. (2004). Gene–environment interaction and the genetics of depression. Journal of Psychiatry and Neuroscience, 29(3), 174-184.

McGowan, P. O., & Szyf, M. (2010). The epigenetics of social adversity in early life: implications for mental health outcomes. Neurobiology of disease39(1), 66-72.

Sanders, F., Baltramonaityte, V., Lussier, A., Smith, D.A.C., Dunn, E.C., Walton. E. (2023). Home and epigenome: How DNA methylation could explain the association between housing quality and depression. Neuroscience Applied, Supplement 2. https://doi.org/10.1016/j.nsa.2023.101111

Siegfried, Z., & Simon, I. (2010). DNA methylation and gene expression. Wiley Interdisciplinary Reviews: Systems Biology and Medicine, 2(3), 362-371.

Singh, A., Daniel, L., Baker, E., & Bentley, R. (2019). Housing disadvantage and poor mental health: a systematic review. American journal of preventive medicine, 57(2), 262-272.

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