The American Society of Addiction Medicine defines addiction as “a primary, chronic disease of brain reward, motivation, memory, and related circuitry.” With the recent rise in opioid abuse and overdose, which has quickly become a national health epidemic, scientists are focused increasingly on understanding the science behind addiction and its effect on the brain, in hopes of finding new ways to treat and ultimately prevent the disease from occurring.
Kerry J. Ressler, MD ’97, PhD ’97, chief scientific officer at McLean Hospital and professor of psychiatry at Harvard Medical School, is pursuing groundbreaking research aimed at unraveling the intersections between childhood traumatization and substance use disorders, and their joint associations with post-traumatic stress disorder (PTSD) outcomes. He and his team have interviewed nearly 10,000 patients living in impoverished communities about how trauma and stress affect their lives.
The rates of trauma exposure are very high. In fact, more than 90 percent of those interviewed have been exposed to trauma, such as child abuse and domestic violence, among other factors. His data suggests that a history of trauma and stress increases greatly one’s risk of addiction. Explains Ressler, “This work speaks to the broader problem of addiction as a biological disease. We all have innate drives toward food, sex, and other novelties, but when you begin to abuse drugs, these drives become hijacked so that the normal drives are not nearly as rewarding anymore.”
To combat this problem and ultimately prevent addiction from occurring in the first place, Ressler would like to see the creation of more preventive strategies that help individuals better cope with stress and trauma, beginning in childhood.
Ressler is also pursuing a complementary study regarding the mechanisms of addiction, in which he is examining the amygdala—a part of the brain that plays a central role in how one experiences emotions—and related regions, such as the orbitofrontal cortex (OFC). He and his colleagues’ findings suggest that dysregulation of the OFC-to-amygdala neurocircuit may influence addictive behavior.
Specifically, their findings show that increased levels of a neuroplasticity protein, called brain-derived neurotrophic factor (Bdnf), drive goal-oriented behavior. In contrast, stress or developmental trauma may lead to atrophy of the OFC neurotrophin systems, which in turn can lead to increased habitual behavior, such as drug seeking, that becomes predominant over goal-directed behavior. Targeting these molecular systems may serve as a promising adjunct to behavioral therapies aimed at suppressing or reversing habitual thought or behavioral patterns seen in addiction.
“Within the last several decades, scientists have made significant progress in understanding the changes in brain function that occur with addiction,” says Ressler. “I’m hopeful this progress will soon translate into effective therapeutic and preventive strategies that ensure addiction is no longer a global epidemic.”
Lauren Carr is a freelance science writer based in Massachusetts.