Scans of the injured brain often map out incredible damage, revealing places where the damage can cause memory problems or tremors.
But in rare cases, those scans can reveal the opposite: plots of areas of the brain where the injury miraculously relieves someone’s symptoms, doctors give clues about how they can complete it.
A team of researchers has now revisited a set of images of such brains, taken by cigarette smokers who are addicted to nicotine and whose strokes or other injuries help them quit spontaneously. The results, scientists said, show that the network of interconnected brain regions shows that addiction-related disorders potentially affect millions of Americans.
The study, published Monday in the scientific journal Nature Medicine, recently supports the idea of traction: the addiction resides not in one region of the brain, but in the circuit of regions connected by thread-like nerve fibers.
The results could provide a clear set of goals for the treatment of addiction that delivers electrical impulses to the brain, new technologies that have promised to help people quit smoking.
Dr. Juho Jautsa, one of the lead authors of the study and a neurologist at Turku University in Finland. “We hope that after this, we will have a very good idea about those regions and networks.”
Research over the past two decades has reinforced the idea that addiction is a brain disease. But many still believe that addiction is voluntary.
Some independent experts said that the recent study was an unusually powerful demonstration of the role of the brain in substance use disorders. Among smokers, who have had a stroke or other brain injury that damages certain neural networks, they experience immediate relief from their cravings.
The researchers copied their findings into a separate group of patients with brain injuries who had completed an alcohol risk assessment. The brain network associated with a lower risk of alcohol addiction was similar to the nicotine addictive milder, suggesting that the circuit could underlie a wider set of dependencies.
“I think this could be one of the most influential publications of the decade, not just this year,” he said. Emeritus, a professor of psychiatry at the University of Pennsylvania, and a former deputy director of the Office of National Drugs, said Thomas McLellan. Control policy, which was not included in the study. “It breaks many stereotypes that are still prevalent in the realm of addiction: addiction is bad parenting, addiction is a weak personality, addiction is a lack of morality.”
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In recent years, succession of studies have identified specific areas of the brain where trauma, or injury, has been found to be associated with relief from addiction. But the goals kept changing.
“People were not able to show consistency in the areas involved,” said Dr. Hemad Ikhtiyari, a specialist in addiction treatment at the winning institute for Brain Research in Tulsa, Oklahoma.
In a new study, Dr. Joutsa applied state-of-the-art statistical techniques to an old set of brain scans of smokers in Iowa who had suffered neural injuries. An earlier analysis of similar scans indicated that patients with insulin damage, the area of the brain involved in the conscious request, were more likely to quit smoking.
But Dr. Zautsa, going back to the same scan pixel by pixel, noted that many patients without insula injuries also lost the urge to smoke. “Insula was something in the story, but it wasn’t the whole story,” he said.
Working with Dr. Dr. Michael Fox, an associate professor of neurology at Harvard Medical School. Jotsa examined another set of scans of smokers who had suffered a stroke in Rochester, NY, and found a total of 129 cases.
The team struggled to find individual areas of the brain where injuries reliably helped patients quit smoking. Instead, researchers turned to standard diagrams of brain attachments that chart how the activity of one region is related to the activity of another region.
Suddenly, researchers discovered a network of connected brain areas where injuries provide immediate relief from nicotine cravings and other networks where injuries did not occur.
“What we are experiencing in so many different areas is that our therapeutic targets are not the regions of the brain as we once thought, but are connected to the brain circuit,” said Dr. Fox said. “If you consider the way the brain connects, you can improve the treatment.”
The study did not provide any account of how patients’ home life – for example, how often they came in contact with cigarettes – may have affected their habits. Patients who generally quit smoking immediately after their injuries were thought to have gone into addiction, reported no desire to smoke, and did not resume when they were followed up.
The researchers, however, looked at whether other changes associated with injury – for example, intelligence or mood – could help explain the disappearance of nicotine cravings in some patients. They didn’t seem to make any difference in the end.
Outside experts said the parts of the brain network identified in the study were familiar to them from previous research. Dr. Martijn Figi, a psychiatrist at the Center for Advanced Circuit Therapeutics at Mount Sinai in Manhattan, studies how electrical impulses in the brain can treat obsessive-compulsive disorder, depression and addiction. Addiction, he said, appears to be more commonly associated with under-activity of the brain’s cognitive control circuit and excessive activity of the reward-related circuit.
By applying electrical stimulation to the surface of patients’ heads or using more invasive methods, such as deep stimulation of the brain, doctors can suppress activity in certain regions, mimic the effects of trauma, and stimulate activity in others. The study identified one area, called the medial frontopular cortex, which was found to be a good candidate for stimulus stimulation; The region overlaps with treatment targets recently approved by US regulators to help quit smoking.
The treatment uses an electromagnetic coil placed in front of the patient’s scalp to deliver electric pulses to the surface of the brain. Other techniques include implanting electrodes in specific regions of the brain or permanently inactivating specific brain regions.
“This paper is really interesting in that it clearly indicates some accessible targets,” said Dr. Said Figi.
While brain stimulation has become more common for the treatment of depression and obsessive compulsive disorder, the use of those therapies for addiction has been slow to catch up. The researchers said that this technique would take years to develop.
Although studies have shown that electrical or magnetic stimulation can reduce the craving for addictive substances, it is not clear how long those effects will last. Some of the most promising goals are deep in the mind; Reaching them may require deep brain stimulation or a specific type of coil that has only recently become available, Drs. Figi said.
Even knowing where to direct brain stimulation does not solve the question of which frequency to use, scientists said. And the connections in the brains of different people vary, increasing the likelihood of the need for tailor-made treatment.
People with addiction are slower to accept brain stimuli than people with depression or movement disorders, the researchers said, partially reflecting the taboo surrounding thinking of addiction as a brain disorder.
There can also be structural challenges. Judy Luigges, an assistant professor of psychiatry at Amsterdam University Medical Centers, recruited from a pool of thousands of patients to study deep brain stimulation at de-addiction centers in the Netherlands. In three years, only two patients began the trial.
Dr. Luiges and colleagues wrote that patients with substance use disorder may have partially avoided the procedure because their motivation to address the disease was more volatile than in patients with obsessive-compulsive disorder.
And the very instability that often accompanies substance use disorders can make investing in time-intensive treatment more difficult. Only one-third of the patients who had an appointment with the research team came with a family member or friend, Dr. Luigjes found.
Some scientists are working to allay those concerns. For example, an addiction relief team at Mount Sinai has begun giving patients less invasive brain stimulation at home or in community centers, rather than in a hospital, reducing the barriers to treatment.
But while the brain may be the entry point for the treatment of addiction, Drs. Luiz said it was probably not the most important. Other scientists have also argued in recent years that focusing on models of addictive brain disease has diverted attention and money from research addressing the social and environmental factors that contribute to addiction.
“We’ve put aside a lot of our hopes and money and energy,” she said, referring to the field’s focus on brain stimulation. “I don’t know if it will pay off the way we thought it would.”