Childhood Trauma Changes Biology of Brain


“Early life adversity is the single biggest determinant of psychiatric illness, greater even than genetics,” said Charles Nemeroff, M.D., Ph.D., to attendees at a presidential session.

The Adverse Childhood Experiences studies (1995-1997) and Centers for Disease Control and Prevention surveys (2009 and 2010) offer insight into the types and prevalence of these adverse experiences: 16% to 28% of those surveyed reported childhood physical abuse, 11% to 21% reported sexual abuse, 11% to 35% emotional abuse, and 12% to 16% reported domestic violence in the home.

Other studies have shown that forcible rape is most common at age 14 years; and that forcible fondling, sodomy, and sexual assault with an object peaked at age 4 years and again at age 14 years.

The effect of these childhood experiences is becoming clearer. Nemeroff discussed findings from one meta-analysis that found childhood trauma increased risk of later-life depression by 2.7 times, posttraumatic stress disorder by 4.4 times, anxiety by 2.5 times, alcohol abuse by 1.9 times, and substance abuse by 3.5 times.

Adversity is a risk factor not only for later psychiatric illness but also for diabetes, stroke, and premature mortality, as well as worse financial and educational outcomes.

Many biological domains contribute to this effect, said Nemeroff, a professor of psychiatry and director of the Institute for Early Life Adversity Research in the Dell Medical School at the University of Texas at Austin. One in particular is the hypothalamic-pituitary-adrenal (HPA) axis, which is involved in the body's response to stress. In studies of women with major depression, Nemeroff and colleagues found that those subjected to greater early life stress exhibited higher levels of adrenocorticotropic hormone and cortisol following a stress test, suggesting that cortisol increases seen in depression are likely related to early life stress.

Evidence also shows that inflammatory markers like interleukin-6 increase following stress and are correlated with depression severity.

Genetic factors alone do not determine later-life conditions, but they do contribute to risk or resilience. Studies by Avshalom Caspi, Ph.D., and Terrie Moffitt, Ph.D., both of the Duke Center for Genomic and Computational Biology, found that adults aged 18 to 26 years who were severely maltreated between the ages of 3 and 11 years had an increased risk of depression—but only if they also had particular variants in the 5-HTT gene, which is associated with many psychiatric disorders including depression.

Abuse affects treatment, as well, Nemeroff said. One study of patients with major depressive disorder found that abuse occurring at age 7 or younger predicted poorer outcomes after eight weeks of antidepressant treatment.

Overall, different types of abuse can affect different parts of the brain, said Nemeroff. “These people [who have experienced childhood trauma] have a different brain biology.”

The question for the future is where to intercede to lessen the long-term, neurobiological consequences of child abuse and neglect, said Nemeroff. “How can we prevent these sequelae after we identify early life adversity?” he said. “Everyone wants to do the right thing, but how do we do the right thing when we don’t know what the right thing is?”

Trauma-focused psychotherapy or medications might work. A public health approach to educate the public—and funders of research—could be a good place to start.

(Image: iStock/Sasiistock)