For several decades experts have been telling us that depression is caused by a chemical imbalance. “The causes of depression are not fully understood,” notes an article about depression on Live Science, “but scientists believe that an imbalance in the brain’s signaling chemicals may be responsible for the condition in many of the patients.” This “chemical imbalance” theory has now become a fixture of popular culture.
At the same time, significant research exists linking depression with childhood abuse. However that research has tended to be understated.
Martin Seligman was a pioneer in understanding this link. He did a famous study at the University of Pennsylvania in 1967 in which dogs were administered electric shocks until they reached a state of helplessness. Seligman interpreted this state of helplessness as depression and compared it to depression in humans caused by abusive situations in childhood from which children couldn’t escape. Later, as adults, such people continue to feel helpless in the face of stressful situations and hence internalize their feelings, leading to depression. (Incidentally, Seligman’s experiment was undoubtedly unethical by today’s standards and has been criticized because of this.)
Recent research has backed up Seligman’s findings and has also found the link between childhood abuse and brain chemistry.
One study, in a 2012 issues of the American Journal of Psychiatry, showed that people who suffered from childhood abuse were twice as likely to develop depression. In this meta-analysis, researchers looked at data from 26 studies that involved more than 26,000 people. The research team examined four basic types of abuse: a rejecting interaction from a mother; harsh discipline reported by a parent; an unstable primary caregiver arrangement throughout childhood; and self-reports of harsh physical or sexual maltreatment. If a person had two of these in his childhood he was considered abused.
A 2013 study done at the University of Wisconsin found a connection between childhood abuse, adolescent depression and changes in the brain. These researchers conducted brain scans of teenagers which revealed weaker connections between the prefrontal cortex and the hippocampus in both boys and girls. The 64 subjects, all eighteen years old, took part in the study; all had suffered from physical or emotional abuse in their childhoods.
A similar study was conducted at Harvard University in 2011. In this study researchers scanned the brains of 200 adults and found significant changes to their brains. Those who had suffered childhood abuse showed an average of a 6% reduction in two parts of the hippocampus, and a 4% reduction in the sections of the brain known as the subiculum and presubiculum, compared with people who had not been abused. Researchers concluded that early stress from childhood abuse makes the brain less resilient to the effects of later stress.
These studies are important in that they not only provide evidence that childhood abuse leads to depression, but they also explain how that abuse changes the chemistry of the brain. Formerly the chemical imbalance had been attributed to genetics. The present studies clearly show the connection between environmental stress, the changes in the brain and depression.
Since the time of Sigmund Freud, psychoanalysis has theorized that depression results from environmental factors in childhood. However, these theories were largely dismissed along with many of Freud’s other theories. Perhaps this was an instance of throwing out the baby with the bathwater. Since Freud, others have examined these environmental factors.
John Bowlby, a British psychoanalyst, studied maternal neglect in the 1950s by focusing on children in orphanages, and he noted that such neglect led to grief and mourning. He went on to postulate that loss of a mother figure in the period between six months to three or four years is a traumatic event that can lead to depression. “The reason for this…is that the processes of mourning to which it habitually gives rise all too readily at this age takes a course unfavorable to future personality development.” (Fine, 1990)
These new studies also have implications with regard to the treatment of depression. Psychiatry, viewing depression for the most part as a chemical imbalance, treats it with chemicals (medications), or in severe cases with electroshock therapy. However, psychotherapists focus on the traumas of childhood and try to bring about change by helping clients to talk through those traumas. Psychotherapy has proven to be effective with all but the most severe cases.
Fine, R. (1990), The History of Psychoanalysis, New York, Jason Aronson, p. 432.