The traumatic experiences of childhood, such as abuse, neglect, or growing up in a harsh environment, can lead to increased psychological and physiological health risks as an individual grows into adulthood. This includes issues such as depression, anxiety disorder, substance dependency, obesity, diabetes, cardiovascular diseases, and even cancer. Some studies show that people who have experienced childhood traumas may have their life expectancy shortened by an average of about 20 years compared to those who did not suffer such traumas.
In the 1950s, psychologist Harry Harlow conducted experiments that revealed the profound impact of early parental separation on the subsequent lives of rhesus monkeys. Research indicated that these trauma-experienced monkeys, as adults, had significant changes in brain structure and chemistry. For humans, adults who suffered childhood traumas often have smaller hippocampal and prefrontal cortex volumes, are more sensitive to stress, and are prone to inflammatory responses.
Deeper evidence indicates that childhood trauma affects not only the physiological aspects of an organism but also leads to changes at the genetic level. Our DNA sequence is largely determined at the moment of fertilization, and the DNA sequence of cells throughout the body does not change much throughout life, except in special circumstances such as random genetic mutations. Despite cells having nearly identical DNA, different types of cells perform different functions, such as brain cells and kidney cells, which is mainly attributed to the role of epigenetics.
During embryonic development, cells begin to differentiate and produce different epigenetic modifications. These modifications regulate gene expression without changing the DNA sequence itself. These include DNA methylation, chromatin modifications, and non-coding RNA regulation. Because of the presence of these epigenetic modifications, cells are able to express different shapes and quantities of proteins, thereby fulfilling different cell functions.
As we are born and enter society, various environmental factors, especially various harmful chemicals, often cause epigenetic changes in our cells. This change is an adaptive mechanism of our life organism and its genetic material in response to environmental challenges. Moderate epigenetic adjustments are beneficial for us to adapt to changes in the environment, but if these adjustments do not match the actual living environment, it may lead to various health problems.
The trauma encountered during childhood is an extreme case that affects genetic epigenetic modifications. Psychological stress is a natural response when humans feel threatened, which is usually very important for eliciting our actions and physiological responses to threats. However, severe trauma in childhood often means prolonged or extreme stress, causing the psychological, behavioral, and physiological response systems to remain highly active for a long time, resulting in the dysregulation of endocrine, nervous, and immune systems, all of which may cause long-lasting negative psychological and behavioral consequences.
Studies show that rats deprived of maternal care during their infancy have the glucocorticoid receptor gene in their brains become highly methylated, increasing their sensitivity to stress and resulting in persistent stress and anxiety responses. In addition, research analyzing the brains of individuals who have committed suicide and found that those who were abused or neglected in childhood had higher levels of methylation in the promoter of the glucocorticoid receptor gene in hippocampal neurons, leading to reduced expression of this receptor gene. This further enhances their hypothalamic-pituitary-adrenal axis response to stress, making them more likely to develop emotional regulation disorders and raising their risk of mental illness.
Other studies have also revealed a 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 as many as 362 gene promoters in the hippocampal neurons of their brain tissue. In the same year, another study found that adults who were abused as children showed methylation differences in the promoters of 997 genes in their whole blood DNA. Interestingly, another analysis targeting the T-cell genomes of adult males pointed out that those abused by their parents between the ages of 6 to 15 exhibited significant methylation differences in 448 gene promoters.
Many existing studies indicate that childhood adversity or trauma affects the epigenetic modification of glucocorticoid receptors. Moreover, this trauma is also linked to epigenetic changes related to psychological states and behaviors, such as the posterior pituitary oxytocin, serotonin, and inflammatory responses. This series of epigenetic changes may have a profound effect on a person’s mental and physical health, and are closely related to an increased risk of various psychological and physical diseases.
Epigenetic changes can be seen as the body’s adaptation to environmental challenges, especially adversities encountered during childhood. These genetic-level impacts may, in some cases, accompany an individual throughout life. It is important to recognize that, although these changes are often long-lasting, current scientific research indicates that they can be reversed through specific interventions, such as pharmacotherapy or environmental changes.
As we embark on the journey of life, childhood is just a starting point. In the long course of life, we still have infinite possibilities to seek and feel love, to change our own destiny. In addition, we know that scientific research itself is also a form of expression, not only spreading knowledge through traditional academic publications, but also seen in the work “Epigenetics of Early-Life Adversity” by Siena Dumas Ang from Princeton University, which is not only a creative piece that won the “Dance Your Ph.D.” contest, but also a way to discuss scientific concepts through the art form of dance.
Indeed, continuing to explore potential therapeutic methods in this field will provide us with important insights on how to improve the quality of life for those who have suffered early adversity.
