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Gudsnuk K, Champagne FA. Epigenetic influence of stress and the social environment. ILAR J. 2012;53(3-4):279-88. doi: 10.1093/ilar.53.3-4.279. PMID: 23744967; PMCID: PMC4021821.
Epigenetics is the study of factors that can cause changes to the body’s genetic information without any modifications to the genetic sequence. From a human perspective, epigenetics is often prevalent in the early stages of life, when factors such as nutrition, nurturing, exposure to substances, and stress can affect an individual’s physical and mental health in the future. In humans, development before birth and directly after birth in infancy are generally when factors such as stress and environmental toxins create the most lasting impact on neurological behavior in the future. However, research has shown that even in adolescence, epigenetic factors can significantly impact an individual’s brain.
For example, exposure to stressors during infancy has been linked to upregulation of the hypothalamic-pituitary-adrenal response to stress, the body’s main system of response to stressors. Upregulation of this response means that the body reacts stronger to facing stress, releasing hormones like cortisol that help increase energy levels and allow the body to deal better with stress. It has also been linked to downregulation of the system that helps the body return to a normal calm state, meaning it is more difficult for the body to get out of the “stress mode.” In experiments done on rodents, it was discovered that exposure to loud noise, strong lighting, and predator scents increased the presence of a hormone called corticosterone, which helps trigger stress responses.
An increased exposure to stress leads to long-term impacts on the individual. Those who were faced with higher levels of stress in youth were often less likely to cope well with stress in adulthood due to their impaired stress response systems. Additionally, a link between stress in youth and reduced reproduction abilities has been found by researchers. After puberty, there is a decrease of hormones in the reproductive organs, likely resulting in reduced fertility rates. In animal test subjects, a decrease in sexual dimorphism, which is the difference between individuals of the opposite sex of the same species, has also resulted from stress.
During development, social interaction is incredibly important. When left unattended and isolated, individuals were more likely to have higher levels of long-term stress and anxiety. On the other hand, a greater exposure to socializing experiences was linked to improved learning and reduced symptoms of anxiety. However, socialization must generally be positive. When larger adults expressing aggressive or negative behavior are present, there was found to be a greater presence of stress and a negative effect on stress response. Even after childhood, similar negative experiences can have lasting impacts on an individual’s genetic responses.
The implications of these discoveries are numerous. Crucially, human caregivers can apply these findings to raising children or other individuals. The field of epigenetics could have interdisciplinary connections to fields like psychology, neuroscience, and even social work. An acknowledgment of the effects and perception of human actions and environments is important in understanding the development of an individual throughout each stage of their life.
By Jeannine Yu
References:
“Downregulation and Upregulation.” Downregulation and Upregulation - an Overview | ScienceDirect Topics, www.sciencedirect.com/topics/biochemistry-genetics-and-molecular-biology/downregulation-and-upregulation. Accessed 3 Oct. 2023.
Dunlavey, Catherine J. “Introduction to the Hypothalamic-Pituitary-Adrenal Axis: Healthy and Dysregulated Stress Responses, Developmental Stress and Neurodegeneration.” Journal of Undergraduate Neuroscience Education : JUNE : A Publication of FUN, Faculty for Undergraduate Neuroscience, U.S. National Library of Medicine, 15 June 2018, www.ncbi.nlm.nih.gov/pmc/articles/PMC6057754/#:~:text=The%20hypothalamic%2Dpituitary%2Dadrenal%20axis%20(HPA)%20is%20the,Breedlove%20and%20Watson%2C%202013).
Dunlavey, Catherine J. “Introduction to the Hypothalamic-Pituitary-Adrenal Axis: Healthy and Dysregulated Stress Responses, Developmental Stress and Neurodegeneration.” Journal of Undergraduate Neuroscience Education : JUNE : A Publication of FUN, Faculty for Undergraduate Neuroscience, U.S. National Library of Medicine, 15 June 2018, www.ncbi.nlm.nih.gov/pmc/articles/PMC6057754/#:~:text=The%20hypothalamic%2Dpituitary%2Dadrenal%20axis%20(HPA)%20is%20the,Breedlove%20and%20Watson%2C%202013).
“What Is Epigenetics?” Centers for Disease Control and Prevention, Centers for Disease Control and Prevention, 15 Aug. 2022, www.cdc.gov/genomics/disease/epigenetics.htm#:~:text=Epigenetics%20is%20the%20study%20of,body%20reads%20a%20DNA%20sequence.
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