Effects of Epigenetics on Mental Health

This article will explore the role of epigenetics in mental health. Epigenetics refers to the heritable changes in gene expression. Learn about important mechanisms of epigenetics, diseases associated with epigenetics, and causes of epigenetics.

The article "Genetics, Epigenetic Mechanism" by Al Nora provides an overview of epigenetic mechanisms that cause changes in chromosomes. The main epigenetic mechanisms are DNA methylation, histone modification, and non-coding RNA-associated gene silencing. DNA methylation usually acts as a gene repressor by stopping gene transcription at the promoter.  Methyl groups are added to the DNA molecule without altering its sequence. Gene expression is repressed by proteins or by inhibiting the ability of transcription factors to bind. Histone modifications such as acetylation, methylation, phosphorylation, and ubiquitylation can alter chromatin structure and gene expression. Environmental factors such as diet, smoking, and stress can influence epigenetic modifications. 

Grezenko Han in "Epigenetics in Neurological and Psychiatric Disorders" described specific neurological disorders that could be the result of epigenetics. For example, Alzheimer's, Parkinson's, and Huntington's diseases, as well as psychiatric disorders such as depression, schizophrenia, and autism, are the result of epigenetics. Scientists have developed biomarker identification, where DNA methylation patterns can be detected before the onset of a symptom. Earlier detection means the possibility of preventing some neurological disorders. Treatment plans need to be personalized due to the diversity of each individual. These neurological disorders require combination therapies to address different aspects of the disorder. For example, behavioral therapy addresses lifestyle factors, and epigenetic therapy focuses on reversing epigenetic changes associated with diseased cells. 

One study in mice was conducted by Kerry Ressler, a neurobiologist and psychiatrist at Emory University, along with his colleague Brian Dias. The scientists placed male mice in a chamber while the scent of acetophenone, which supposedly smells like cherries and almonds, was blown in their direction. Once the chemical diffused through the chamber, Ressler and Dias gave the mice small electric shocks. They repeated this process until the mice learned to associate the smell of acetophenone with pain. The scientist continued to spread the scent of acetophenone, only this time without delivering a shock. The mice shuddered in fear, anticipating a shock. When the mice went on to have children, their offspring seemed to inherit the fear of acetophenone. Although they never experienced the electric shock, the offspring experienced heightened sensitivity and shuddering when introduced to the odor. Similarly, the third generation of mice appeared to inherit the response. Other experiments showed similar behavior when tested on female mice. 

According to the article "The Role of Epigenetics in Psychological Resilience," there are 3 main ways that epigenetics contributes to psychological resilience. First, epigenetic differences are present due to genetic variation or direct inheritance. Genetic variation can directly affect DNA methylation sites, which can make a gene more at risk for a mental disorder. Epigenetic variation from direct inheritance, as in the mouse experiment, can help subsequent generations adapt to the environment. Some researchers are focusing on the link between traumatic experiences and an increased likelihood of developing psychopathy. Second, epigenetic modifications are affected by environmental exposures, especially in the early stages of development. The epigenome is sensitive in the early stages of development, making it vulnerable to stress, trauma, and abuse. Subsequent generations have been found to be more sensitive and less resilient. However, in the absence of a negative environment, research suggests that positive parental care can promote resilience despite a natural hormonal response at birth. The final and third way epigenetics contributes to psychological resilience is through exposure to adversity. There is evidence that adversity can affect the epigenome, although some people don't consider adversity in epigenetics. On the other hand, there are many psychological developments, so adversity should be considered due to the high level of diversity in each being. Scientists hypothesize that adverse and traumatic events can be biologically embedded in someone's genome and contribute to differences in psychological resilience among individuals. 

Epigenetics can affect mental health in many ways. It can be inherited, but it can also be altered in early childhood. The field of epigenetics is still evolving as more research is conducted. 

Bibliography: 

Al, Nora M, et al. “Genetics, Epigenetic Mechanism.” Nih.gov, StatPearls Publishing, 5 Apr. 2019, www.ncbi.nlm.nih.gov/books/NBK532999/.

Grezenko, Han, et al. “Epigenetics in Neurological and Psychiatric Disorders: A Comprehensive Review of Current Understanding and Future Perspectives.” Cureus, vol. 15, no. 8, 2023, p. e43960, www.ncbi.nlm.nih.gov/pmc/articles/PMC10446850/, https://doi.org/10.7759/cureus.43960.

magazine, Ewen Callaway,Nature. “Fearful Memories Passed down to Mouse Descendants.” Scientific American, 1 Dec. 2013, www.scientificamerican.com/article/fearful-memories-passed-down/.

Smeeth, Demelza. “The Role of Epigenetics in Psychological Resilience.” The Lancet Psychiatry, vol. 8, no. 7, 1 July 2021, pp. 620–629, www.sciencedirect.com/science/article/abs/pii/S2215036620305150, https://doi.org/10.1016/S2215-0366(20)30515-0.