A study of people who effortlessly quit smoking after a stroke or other brain injury—and of those who suffered an injury but then kept smoking—has pinpointed a brain network involved in addiction, researchers reported June 13 in Nature Medicine. Experts say the findings may help identify targets for therapies that could treat addictions.
“I think this could be one of the most influential publications not only of the year, but of the decade,” A. Thomas McLellan, a professor emeritus of psychiatry at the University of Pennsylvania who also served as deputy director of the US Office of National Drug Control Policy, tells The New York Times. “It puts to rest so many of the stereotypes that still pervade the field of addiction: that addiction is bad parenting, addiction is weak personality, addiction is a lack of morality.” McLellan was not involved in the current research.
In the study, researchers compared the brain scans of 34 people who suddenly quit smoking following a focal brain injury, such as from a stroke, with those of 69 people who continued smoking after such an injury. Study coauthor Juho Joutsa of the University of Turku in Finland tells New Scientist that those who quit had damage to either the dorsal cingulate, the lateral prefrontal cortex, the insula, or to regions that were strongly connected to one of these areas via nerves. Together, these areas seem to comprise an addiction circuit, he tells the magazine. Looking at a separate cohort of 186 patients, the researchers also found that damage to this circuit was associated with a lower likelihood of alcohol addiction, indicating that the circuit may be implicated in addiction generally.
The results suggest that targeting the medial prefrontal cortex, a brain area that tamps down activity in the identified circuit, with transcranial magnetic stimulation might be a promising treatment avenue, Joutsa tells New Scientist. “What we’re realizing across many different fields is that our therapeutic targets are not brain regions, as we once thought, but connected brain circuits,” study coauthor Michael Fox of Harvard Medical School tells the Times. “If you take into account the way the brain is connected, you can improve treatment.”
But some experts tell the Times that there could be challenges to a brain stimulation-based approach, including figuring out which frequency of magnetic stimulation to use, the possibility that treatments would need to be individually tailored, and the challenge of making treatments consistently accessible to people with addictions.