Epigenetics and Depression: How Environment Impacts Mental Health

Over 17 million adults in the United States had at least one major depressive episode in 2017 (National Institute of Mental Health, 2019). Globally, more than 264 million people of all ages experience depression (World Health Organization, 2020).

In the United States, major depressive episodes are more common among adult women (8.7%) than adult men (5.3%). At 13.1%, young adults, aged 18-25, had the highest rate of major depressive episodes (National Institute of Mental Health, 2019).

As our understanding of mental health increases, we are beginning to look at how the environment of our parents and grandparents influences our own health and the health of our offspring. This knowledge is based on new research that investigates the epigenetic processes which regulate how the environment affects the expression of genes that relate to mental health generally and to depression in particular (Sun et al., 2013).

As our understanding of mental health increases, we are beginning to look at how the environment of our parents and grandparents influences our own health and the health of our offspring.

Environmental Impacts of Depression: Past and Present

Mental illness is incredibly complex and is influenced by a host of biological, chemical, and environmental factors. Depression, for example, is much more than low mood, negative thoughts, or a chemical imbalance in the brain. When we look at the biological component of depression, we see just how powerfully environment may determine our vulnerability to developing depression and how these environmental effects occur and accumulate over the generations.

We know childhood abuse and neglect can have lifelong impacts on the health and well-being of the child. But what about looking into the environment of our ancestors? We are beginning to understand how our parents’ and grandparents’ environment impacts our own and our children’s mental health.

Epigenetics, in its simplest meaning, refers to the stable changes in gene expression without modification of the DNA sequence. In the context of depression, these changes are often triggered by severe stress, and they can result in an increased vulnerability in the brain’s limbic regions (Nestler, 2014). The limbic regions of the brain are implicated in depression, as they are involved in emotion regulation, self-preservation, and the desire to procreate (Pandya et al., 2012). These changes in gene expression can be passed down from parents to offspring. However, the exact process of how this happens is still largely mysterious (Kaneshiro et al., 2019).

While the mechanism of transmission is not clear, the results of environmental exposure to risk factors for depression are measurable. We now know that the stress of our parents and grandparents can cause increased vulnerability to depression in ourselves and our children. The vulnerability to depression can be passed down through generations. This is true even though we may not have experienced early abuse, trauma, or neglect.

Change in Both Directions: How Environment Can Nurture

Epigenetic changes can also occur because of positive experiences such as supportive, healthy relationships and learning opportunities. Good physical health also influences gene expression in a positive way. Having access to nutritious food and a healthy lifestyle may also have a protective effect on mental health.

Even in adulthood, our brain continually changes with experience. For example, chronic anxiety resulting from early adverse childhood experiences can be improved by stress-reduction interventions (Hölzel et al., 2010). For adults, living in a healthy environment without prolonged exposure to severe stress can have a real impact on increasing resilience and reducing a person’s vulnerability to developing a mental health issue.

If we provide a healthy, nurturing environment with supportive relationships for our children, we can improve their resilience against developing depression. A healthy diet and exercise are included as part of an optimal environment for children. (According to researchers, a healthy diet, especially for growing infants and children, does not mean a fat-free diet. Fat is essential for neurological development and brain function (Milner & Allison, 1999).)

Therapy Can Improve Resilience

Part of moving toward a healthy lifestyle can include working with a therapist who incorporates cognitive behavioral therapy (CBT). CBT is an individualized process that has been shown to be effective for reducing stress, anxiety, and depression. CBT works on negative and unrealistic thought patterns and unhelpful behaviors. Additionally, therapy is a supportive relationship that allows for the healing of underlying issues that may be causing distress. Therapy and CBT can lead to improvements in mood and reduction in stress that will reduce anxiety and, over time, lead to improvements in brain areas associated with depression.

In summation, our environment, even the environment of our parents and grandparents, has an important impact on our mental health. It is important to understand that when you take care of yourself and your children, you are not only improving your own health—you may also be improving the lives and health of future generations who have not even been born yet.

References:

1. Depression. (2020, January 30). World Health Organization (WHO). Retrieved from https://www.who.int/news-room/fact-sheets/detail/depression
2. Hölzel, B. K., Carmody, J., Evans, K. C., Hoge, E. A., Dusek, J. A., Morgan, L., Pitman, R. K., & Lazar, S. W. (2010). Stress reduction correlates with structural changes in the amygdala. Social Cognitive and Affective Neuroscience, 5(1), 11-17. doi: 10.1093/scan/nsp034
3. Kaneshiro, K. R., Rechtsteiner, A., & Strome, S. (2019, March 20). Sperm-inherited H3K27me3 impacts offspring transcription and development in C. elegans. Nature Communications, 10(1271). Retrieved from https://www.nature.com/articles/s41467-019-09141-w
4. Major depression. (2019). National Institute of Mental Health (NIMH). Retrieved from https://www.nimh.nih.gov/health/statistics/major-depression.shtml
5. Milner, J. A., & Allison, R. G. (1999). The role of dietary fat in child nutrition and development: Summary of an ASNS workshop. The Journal of Nutrition, 129(11), 2094-2105. doi: 10.1093/jn/129.11.2094
6. Nestler, E. J. (2014). Epigenetic mechanisms of depression. JAMA Psychiatry, 71(4), 454-456. doi: 10.1001/jamapsychiatry.2013.4291
7. Pandya, M., Altinay, M., Malone, D. A., & Anand, A. (2012). Where in the brain is depression?. Current Psychiatry Reports, 14(6), 634-642. doi: 10.1007/s11920-012-0322-7
8. Sun, H., Kennedy, P. J., & Nestler, E. J. (2013). Epigenetics of the depressed brain: Role of histone acetylation and methylation. Neuropsychopharmacology, 38(1), 124-137. doi: 10.1038/npp.2012.73

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