The traumatic experiences of childhood, such as abuse, neglect, or growing up in a harsh environment, may lead to an increased risk of psychological and physiological health problems in adulthood. This includes issues such as depression, anxiety, substance dependence, obesity, diabetes, cardiovascular disease, and cancer. Some research suggests that the average lifespan of individuals who have experienced childhood trauma may be up to 20 years shorter compared to those who have not.
In the 1950s, psychologist Harry Harlow conducted experiments revealing the profound effects of early parental separation on rhesus monkeys later in life. Studies have shown that these traumatized monkeys exhibit significant changes in brain structure and chemistry as adults. For humans, adults who have suffered childhood trauma often have a smaller hippocampus and prefrontal cortex, increased sensitivity to stress, and are more prone to inflammatory responses.
Further evidence indicates that childhood trauma affects not just the biological physiological aspects, but also leads to changes at the genetic level. Our DNA sequence is largely determined at conception, and the sequence of DNA in all cells remains nearly unchanged throughout life, except in cases of random genetic mutations and other special circumstances. Despite having nearly identical DNA, cells are different, such as brain cells and kidney cells, which perform different functions due largely to the role of epigenetics.
During embryonic development, cells begin to differentiate and acquire different epigenetic modifications. These modifications regulate gene expression without altering the DNA sequence itself. This includes DNA methylation, chromatin modification, and the regulation of non-coding RNA, among others. Because of these epigenetic modifications, cells are able to express different shapes and quantities of proteins, thus fulfilling different cellular functions.
As we enter society after birth, various environmental factors, especially various harmful chemicals, often cause epigenetic changes in our cells. This change is an adaptive mechanism by which our organism and its genetic material respond to environmental challenges. Moderate epigenetic adjustments are beneficial for us to adapt to environmental changes, but if these adjustments do not match the actual living environment, they may lead to various health problems.
Childhood trauma is an extreme example of how gene epigenetic modifications can be affected. Psychological stress is a natural response when a person perceives a threat, which is often crucial for stimulating our behavioral and physiological reactions to cope with the threat. However, severe trauma in childhood often means prolonged or extreme stress, leading to long-term hyperactivity in the systems of psychological, behavioral, and physiological responses, which can cause dysregulation of the endocrine, neurological, and immune systems. These can potentially result in lasting negative psychological and behavioral consequences.
Research shows that if rats lack maternal care in their youth, the genes for glucocorticoid receptors in their brains that are responsible for managing stress responses become highly methylated, increasing their sensitivity to stress and leading to persistent stress and anxiety responses. Furthermore, studies analyzing the brains of individuals who have committed suicide found that those who suffered abuse or neglect in childhood had higher levels of methylation in the promoter of the glucocorticoid receptor gene in hippocampal neurons. This led to reduced expression of this receptor gene, which in turn enhanced their hypothalamic-pituitary-adrenal axis response to stress, making them more prone to emotional regulation disorders and increasing their risk of mental illness.
Other studies have also revealed the correlation between childhood violence or abuse and epigenetic changes. For example, one study found that in individuals who suffered significant abuse during childhood, there were methylation differences in the promoters of up to 362 genes within the neurons of the hippocampus in their brain tissue. A study from the same year discovered that adults who were abused as children had methylation differences in 997 gene promoters in their whole blood DNA. Interestingly, another analysis focusing on the T-cell genome of adult males also pointed out that those individuals who were abused by their parents between the ages of 6 to 15 exhibited significant methylation differences in 448 gene promoters.
Many existing studies collectively suggest that adversities or traumas encountered during childhood can affect the epigenetic changes of the glucocorticoid receptor. Furthermore, such traumas are also linked to the epigenetic changes related to psychological states and behavior, involving the posterior pituitary oxytocin, serotonin, and inflammatory response. This series of epigenetic changes may have profound effects on a person’s mental health and physiological condition and are closely related to an increased risk of various psychological and physiological diseases.
Epigenetic changes can be viewed as the body’s adaptation to environmental challenges, especially the adversities encountered during childhood. This kind of impact at the genetic level may, in certain cases, accompany an individual for life. It is important to realize that although these changes are usually long-term, existing scientific research shows that they can be reversed through specific intervention measures, such as pharmacotherapy or environmental changes.
As we start the journey of life, childhood is just a starting point. Throughout our long lives, we still have endless possibilities to seek and feel love, to change our fate. In addition, we know that scientific research itself is also a form of expression, not only through traditional academic publications to spread knowledge, as evidenced by Siena Dumas Ang’s ‘Epigenetics of Early Adversity’ from Princeton University. It is not only a creative piece that won the “Your Ph.D. Dance” contest but also an exploration of scientific concepts through the art form of dance.
In fact, continuing to explore potential therapeutic approaches in this area will offer us important insights into how to improve the quality of life for people who have suffered adversities in their early years.
