They were cigarette smokers. Then the stroke defeated their attitude.

Damaged brain scans often produce a map of irreversible losses, revealing spots where the injury causes memory loss or tremors.

But in rare cases, this scan can reveal the complete opposite: areas of the brain where the lesion miraculously relieves someone of symptoms, giving us clues as to how doctors can do the same.

The team of researchers is now reviewing a collection of such brain images compiled by nicotine-dependent cigarette smokers who have had a stroke or other injury spontaneously helped them quit smoking. The scientists said the results showed a network of interconnected regions of the brain that they believe underlie addiction-related disorders that potentially affect tens of millions of Americans.

The study, published Monday in the scientific journal Nature Medicine, supports an idea that has just spread: that addiction lives not in certain regions of the brain, but in regions connected by thread-like nerve fibers.

The results could provide clearer goals for addiction treatment, delivering electrical pulses to the brain, a new technique that has shown promise that has helped people quit smoking.

“One of the biggest problems with addiction is that we do not really know where the main problem in the brain is that we need to seek treatment,” said Dr. Juho Jutza, one of the study’s lead authors and a university neurologist. Turku in Finland. We hope that after this we will have a very good idea about these regions and networks.

Studies over the past two decades have reinforced the notion that addiction is a brain disease. But many still believe that addiction is voluntary.

Some independent experts said the latest study was an unusually strong demonstration of the role of the brain in substance use disorders. Among smokers who have had a stroke or other brain injury, those who have damaged a particular neural network are instantly relieved of their cravings.

The researchers repeated their findings in a separate group of patients with brain injuries who completed a risk assessment for alcoholism. The brain network associated with a lower risk of alcohol dependence was similar to that of a network that alleviated nicotine dependence, indicating that the circle may be based on broader addictions.

“I think this could be one of the most influential publications not only for a year, but for a decade,” he said. Thomas McLellan, Emeritus of the University of Pennsylvania Psychiatrist and former Deputy Director of the National Office on Drugs. Control policies that were not included in the study. “It alleviates many stereotypes that still prevail in the realm of addiction: that addiction is a bad upbringing, drug addiction is a weak person, addiction is a lack of morality.”

In recent years, a number of studies have identified specific regions of the brain where injury or damage appears to be related to addiction relief. But the goals were changing.

“People have not been able to show consistency in the areas involved,” said Dr. Hamed Ekhtiar, an addiction treatment expert at the Brain Research Institute in Tula, Okla.

In a new study, Dr. Jutsa used sophisticated statistical techniques on an old set of brain scans of Iowa smokers who had nerve damage. An earlier analysis of the same scan showed that patients who had damaged insulin, a region of the brain involved in conscious needs, were more likely to quit smoking.

But Dr. Jutsa, while returning to pixel-by-pixel-by-pixel-by-pixel on the same scan, noticed that many patients who did not have insulin injuries also lost the urge to smoke. “There was something in the history of insula, but that was not the whole story,” he said.

With Dr. Michael Fox, an associate professor of neurology at Harvard Medical School, Dr. Yutza examined a second set of scanners of smokers who suffered a stroke in Rochester, New York, for a total of 129 cases.

The team struggled to find individual regions of the brain where the injuries reliably helped patients quit smoking. Instead, the researchers used standard diagrams of brain connections that show how activity is related to activity in one region.

Suddenly, researchers were able to find networks of brain-connected regions where injuries caused instant relief from nicotine cravings, and other networks where there were no injuries.

“What we are realizing in many different areas is that our therapeutic goals are not brain regions as we previously thought, but brain circuits,” Dr. Fox said. “If you consider brain connections, you can improve treatment.”

The study did not look at how patients’ domestic lives – such as how often they were exposed to cigarettes – affected their habits. Patients who were considered to have switched to addiction remission after their injuries usually stopped smoking immediately stated that they had no desire to smoke and did not start again until they were monitored.

However, researchers looked to see if other damage-related changes – such as intelligence or mood – could help explain the disappearance of nicotine cravings in some patients. They finally saw no difference.

External experts said parts of the brain network identified in the study were familiar to them from earlier studies. Dr. Martin Figg, a psychiatrist at the Advanced Circular Therapy Center on Mount Sinai in Manhattan, is studying how electrical impulses delivered to the brain treat obsessive-compulsive disorder, depression, and addiction. He said the attitude appears to be related to insufficient activity of the cognitive control circuits in the brain and excessive activity of reward-related circuits.

By using electrical stimulation of patients on their surface or by using more invasive methods such as deep brain stimulation, physicians can inhibit activity in certain regions, mimic the effects of trauma, and stimulate activity in others. The study revealed one region called the medial frontopolar cortex, which appeared to be a good candidate for excitation stimulation; This region coincided with the goal of a treatment recently approved by U.S. regulators to help smokers smoke.

This treatment uses an electromagnetic coil placed on the patient’s scalp to deliver electrical impulses to the surface of the brain. Other techniques include implanting electrodes in certain regions of the brain or permanent deactivation in specific regions of the brain.

“This paper is really interesting in that it clearly points out some of the available treatment targets,” Dr. Figi said.

Although brain stimulation has become more common in the treatment of depression and obsessive compulsive disorder, the use of these addiction therapies is slower. The researchers said it would take years to refine the technique.

Although studies show that electrical or magnetic stimulation can reduce cravings for drugs, it is not clear how long this effect lasts. Some of the most promising targets are in the brain; Achieving them may require deep brain stimulation or a specific type of helix that has just become available, said Dr. Figi.

Knowing where to turn for brain stimulation also does not solve the question of what frequency to use, scientists said. And connections are different in different human brains, which increases the prospect of the need to adjust treatment.

People with addictions receive brain stimulation more slowly than people with depression or movement disorders, say researchers, which partly reflects the taboo of thinking about addiction as a brain disorder.

There may also be structural challenges. Judy Luiges, an assistant professor of psychiatry at the University of Amsterdam Medical Center, has taken thousands of patients from a group of drug addicts in the Netherlands to study deep brain stimulation. In three years, only two patients began testing.

Dr. Luiges and colleagues wrote that patients with substance use disorders may avoid the procedure in part because their motivation for the disease varied more than in patients with obsessive-compulsive disorder.

And the instability itself, which is often accompanied by substance abuse disorders, can complicate investments in time-intensive treatment. Dr. Luiges found that only a third of the patients who met the study group brought a family member or friend.

Some scientists are working to solve these problems. For example, a drug group in Mount Sinai brought less invasive brain stimulation to patients at home or in community centers than in a hospital, reducing treatment barriers.

But while the brain may be the entry point for addiction treatment, Dr. Luiges said it probably was not the most important. Other scientists have argued in recent years that the focus on the addiction brain disease model has shifted attention and money from studies related to the social and environmental factors that contribute to addiction.

“We put our hopes, money and energy on one side too much,” he said, referring to the field focusing on brain stimulation. “I do not know if it will be paid as we thought.”

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