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Scanning an injured brain usually maps out the irreversible loss and reveals points where the damage has caused memory difficulties or tremors.

But in rare cases, these scans can reveal the opposite: Drawings of brain regions where an injury miraculously relieved someone’s symptoms offer clues as to how doctors can achieve the same.

A research team has now taken a fresh look at a series of such brain images taken from nicotine-addicted smokers who have helped strokes or other injuries spontaneously quit. The results show a network of interconnected brain regions that they believe underlie the addiction-related disorders that potentially affect tens of millions of Americans, the scientists said.

StudyPublished Monday in the scientific journal Nature Medicine, it supports an idea that has gained some attention recently: that addiction does not live in one brain region or the other, but in a circuit of regions connected by thread-like nerve fibers.

The results may provide a clearer set of targets for addiction treatments that deliver electrical pulses to the brain, new techniques that show promise in helping people quit smoking.

One of the study’s lead authors and a neurologist at the university, Dr. “One of the biggest problems with addiction is that we don’t really know where in the brain the real problem we need to target with treatment is,” said Juho Joutsa. Turku Finland. “From now on, we hope we have a very good idea of ​​these regions and networks.”

Research over the past two decades has solidified the idea that addiction is a brain disease. But many people still believe that addiction is voluntary.

Some independent experts said the latest study is an unusually strong demonstration of the brain’s role in substance use disorders. Among smokers who suffered strokes or other brain injuries, those who damaged a particular neural network were instantly relieved of their cravings.

The researchers replicated their findings in a separate group of patients with brain damage who completed the alcoholism risk assessment. The brain network associated with a lower risk of alcohol dependence was similar to that facilitating nicotine addiction, suggesting that the circuitry may underlie a broader set of addictions.

“I think this may be one of the most influential publications of not just the year, but the decade,” said A. Thomas McLellan, professor emeritus of psychiatry at the University of Pennsylvania and former deputy director of the National Office of Drugs. Control Policy not included in the Study. “It breaks many of the stereotypes that still prevail in the addiction field: that addiction is bad parenting, addiction is weak personality, addiction is immorality.”

In recent years, a number of studies have identified specific brain regions in which a lesion or injury appears to be associated with recovery from addiction. But the goals kept changing.

A specialist in addiction treatments at the Laureate Institute for Brain Research in Tulsa, Okla, Dr. “People have not been successful in demonstrating consistency in relevant areas,” said Hamed Ekhtiari.

In the new study, Dr. Joutsa applied sophisticated statistical techniques to a series of earlier brain scans from smokers in Iowa who had suffered neural injuries. A previous analysis of the same scans had suggested that patients with damage to the insula, a brain region involved in conscious impulses, were more likely to quit smoking.

However, Dr. When Joutsa reviewed the same scans pixel-by-pixel, he noticed that many patients without insula injuries also lost the desire to smoke. “There was something about the Insula story, but that wasn’t the whole story,” he said.

An associate professor of neurology at Harvard Medical School, Dr. Working with Michael Fox, Dr. Joutsa studied a second set of screenings from smokers who had suffered a stroke in Rochester, NY. In total, they looked at 129 cases.

The team struggled to find individual brain regions where injuries reliably help patients quit smoking. Instead, the researchers turned to standard brain connectivity diagrams that show how activity in one area relates to activity in another.

All of a sudden, the researchers were able to detect networks of connected brain regions where injuries cause instant relief from nicotine cravings, and other networks where injuries don’t.

Dr. “What we’ve noticed in many different areas is that our therapeutic targets are not brain regions as we once thought, but interconnected brain circuits,” Fox said. “If you take into account the way the brain is connected, you can improve treatment.”

The study did not explain how the patients’ home life—for example, how often they were exposed to smoking—affected their habits. Patients who were considered to be in addictive remission after their injury generally quit smoking immediately, reporting that they had no desire to smoke and did not relapse while being followed.

However, the researchers looked at whether other injury-related changes—for example, in intelligence or mood—could help explain the loss of nicotine cravings in some patients. They didn’t seem to have made a difference in the end.

Outside experts said the parts of the brain network identified in the study sound familiar to them from previous research. A psychiatrist at the Advanced Circuit Treatment Center at Mount Sinai in Manhattan, Dr. Martijn Figee explores how electrical impulses transmitted to the brain can treat obsessive compulsive disorder, depression and addiction. He said addiction often appears to be associated with underactivity of the brain’s cognitive control circuitry and overactivity of reward-related circuits.

By applying electrical stimulation to the surface of patients’ heads or using more invasive methods such as deep brain stimulation, doctors can suppress activity in certain areas, mimic the effect of an injury, and excite activity in others. The study identified a region called the medial frontopolar cortex that appears to be a good candidate for excitatory stimulation; This region coincides with the goal of a treatment recently approved by US regulators to help smokers quit.

This treatment uses an electromagnetic coil placed on the patient’s scalp to deliver electrical pulses to the surface of the brain. Other techniques involve placing electrodes in specific brain areas or permanently disabling precise brain areas.

Dr. “This paper is really interesting in that it clearly shows some achievable targets for treatments,” said Figee.

While brain stimulation has become more common in the treatment of depression and obsessive-compulsive disorder, these treatments have been slower to be used for addiction. The researchers said it would take years to develop the techniques.

It’s unclear how long these effects last, despite studies showing that electrical or magnetic stimulation can reduce the craving for addictive substances. Some of the most promising targets lie deep in the brain; Dr. Getting to them may require deep brain stimulation or a certain type of coil only recently available, Figee said.

Knowing where to direct brain impulses also doesn’t solve the question of what frequency to use, the scientists said. And the connections in different people’s brains are different, raising the possibility of the need to tailor treatments.

People with addictions are slower to adopt brain stimulation than those with depression or movement disorders, the researchers said, partially reflecting the taboo about thinking of addiction as a brain disorder.

There may also be structural difficulties. Judy Luigjes, assistant professor of psychiatry at the University of Amsterdam Medical Centers, was recruited from a pool of thousands of patients at addiction treatment centers in the Netherlands for the deep brain stimulation study. Within three years, only two patients started trying she.

Dr. Luigjes and colleagues Wrote patients with substance use disorder He may have partially avoided the procedure because his motivations to deal with the disease fluctuate more than in patients with obsessive compulsive disorder.

And the instability that often accompanies substance use disorders can make investing in time-consuming treatments even more difficult. Dr. Luigjes found that only a third of patients who had an appointment with the research team brought a family member or friend.

Some scientists are working to address these concerns. A Addiction team at Mount SinaiFor example, he removed barriers to treatment by applying less invasive brain stimulation to patients at home or community centers rather than hospitals.

But while the brain is an entry point for treating addiction, Dr. Luigjes said that was probably not the most important. Other scientists too discussed in recent years. Focusing on the brain disease model of addiction has shifted attention and money away from research addressing the social and environmental factors that contribute to addiction.

“We put most of our hopes, money, and energy aside,” he said, referring to the field’s focus on brain stimulation. “I don’t know if it’s going to pay off as we think.”