Gray matter is the tissue that processes information in the brain and contains all the neurons in this organ. Brain development continues into adulthood, yet gray matter reaches its peak of growth before adolescence, and new research has revealed that low gray matter volume on the left side of the ventromedial prefrontal cortex may be a “hereditary biomarker” for nicotine addiction and that gray matter levels on both sides of the brain may be linked to desire to start smoking during adolescence and addiction to nicotine.
The study has been carried out by scientists, led by the universities of Cambridge and Warwick in the United Kingdom and Fudan University in China, who analyzed brain images and data on the behavior of 807 young people at the ages of 14, 19 and 23 years and found that, on average, teens who started smoking at age 14 had a significantly less gray matter in a section of the left frontal lobe that is involved in decision making and disobedience to rules.
The researchers further found that the opposite right side of the same brain region also had less gray matter in smokers. Importantly, gray matter loss in the right prefrontal cortex appears to accelerate only after someone has started smoking. This region is linked to sensation seeking. The study used data from the IMAGEN project in four European countries – the United Kingdom, Germany, France and Ireland – and has been published in Nature Communications.
Lack of gray matter can cause disinhibition and impulsivity
In the opinion of the authors of the study, the fact of having less gray matter in the left forebrain could decrease cognitive function and lead to “disinhibition”impulsive behavior that breaks the rules and arises from a limited ability to consider the consequences of our actions, which can increase the chances of starting smoking at an early age.
“Less gray matter in this region of the brain can limit cognitive function, leading to decreased self-control and a propensity for risky behaviors, such as smoking.”
Once a nicotine habit takes hold, the gray matter in the right frontal lobe shrinks, which can weaken control over smoking by impairing “hedonic motivation”: the way in which pleasure is sought and managed. Excessive loss of gray matter on the right side of the brain was also linked to binge drinking and the marijuana use.
Taken together, the findings point to a damaged “neurobehavioral mechanism” that may contribute to nicotine use starting early and developing into a long-term addiction, according to the researchers. “Smoking initiation is most likely to occur during adolescence. Any way to detect a higher likelihood of this so that we can target interventions could help save millions of lives,” said Professor Trevor Robbins, co-lead author of the study. Cambridge Department of Psychology.
“In our study, reduced gray matter in the left prefrontal cortex is associated with increased rule-breaking behavior, as well as earlier smoking experiences. It could be that this rule-breaking leads to rule violations.” smoke-free regulations,” Robbins said.
Co-author Professor Barbara Sahakian, from the Cambridge Department of Psychiatry, explains that “the ventromedial prefrontal cortex is a key region for dopamine, the brain’s pleasure chemical. In addition to playing a role in rewarding experiences, dopamine has long been thought to influence self-control, so “less gray matter in this region of the brain can limit cognitive function, leading to decreased self-control and a propensity for risky behaviors, such as smoking.
The researchers compared brain imaging data from adolescents who had smoked at age 14 with those who had not, and repeated it in the same participants at their 19th and 23rd birthdays. Those who had smoked before the age of 14 had significantly less gray matter in the left prefrontal cortex, on average. Furthermore, those who started smoking at age 19 also had less gray matter in their left prefrontal cortex at age 14, indicating a possible causal relationship.
The scientists also looked at the right ventromedial prefrontal cortex. Gray matter loss occurs as we get older, but both those who smoked since the age of 14 and those who smoked since the age of 19 ended up with excessive gray matter loss in the right frontal lobe.
For the right prefrontal cortex, 19-year-old smokers who did not start in adolescence had gray matter levels similar to those of 14-year-olds who never smoked, suggesting that a rapid reduction in right ventromedial prefrontal cortex only begins with smoking. initiation of smoking. Data at 23 years showed that gray matter volume in the right prefrontal cortex decreased at a faster rate in those who continued to smoke, suggesting an influence of smoking on prefrontal function.
The researchers also analyzed data from two questionnaires completed by the participants to investigate personality traits regarding novelty and sensation seeking. “Both questionnaires examine the search for exciting experiences, but they measure different behaviors,” said Robbins. “The sensation seeking scale focuses on pleasurable experiences, while the novelty seeking questionnaire includes items on impulsivity and rule breaking.”
Less gray matter in the left prefrontal cortex was associated with novelty seeking, particularly a disorderly and transgressive behaviorwhile reduced gray matter volume in the right prefrontal cortex was associated only with sensation seeking.
Lead author Professor Tianye Jia from Fudan University added: “Less gray matter in the left frontal lobes is linked to behaviors that increase the likelihood of smoking in adolescence.” “Smokers then experience excessive loss of gray matter in the right frontal lobes, which is linked to behaviors that reinforce substance use. This may provide a causal explanation of how smoking begins in young people and how it becomes a dependency“.