The trauma of child abuse can last a lifetime, leading to a higher risk of anxiety, depression and suicide further down the line. This link seems obvious, but a group of Canadian scientists have found that it has a genetic basis.
By studying the brains of suicide victims, Patrick McGowan from the Douglas Mental Health University Institute, found that child abuse modifies a gene called NR3C1 that affects a person’s ability to deal with stress. The changes it wrought were “epigenetic”, meaning that the gene’s DNA sequence wasn’t altered but it’s structure was modified to make it less active. These types of changes are very long-lasting, which strongly suggests that the trauma of child abuse could be permanently inscribed onto a person’s genes.
Child abuse, from neglect to physical abuse, affects the workings of an important group of organs called the “hypothalamic-pituitary-adrenal axis” or HPA. This trinity consists of the hypothalamus, a funnel-shaped part of the brain; the pituitary gland, which sits beneath it; and the adrenal glands, which sit above the kidneys. All three organs secrete hormones. Through these chemicals, the HPA axis controls our reactions to stressful situations, triggering a number of physiological changes that prime our bodies for action.
The NR3C1 gene is part of this system. It produces a protein called the glucocorticoid receptor, which sticks to cortisol, the so-called “stress hormone”. Cortisol is produced by the adrenal glands in response to stress, and when it latches on to its receptor, it triggers a chain reaction that deactivates the HPA axis. In this way, our body automatically limits its own response to stressful situations.
Without enough glucocorticoid receptors, this self-control goes awry, which means that the HPA is active in normal situations, as well as stressful ones. No surprise then, that some scientists have found a link between low levels of this receptor and schizophrenia, mood disorders and suicide. So, childhood trauma alters the way the body reacts to stress, which affects a person’s risk of suicide or mental disorders later in life. Now, McGowan’s group have revealed part of the genetic (well, epigenetic) basis behind this link.