Smokers who pick up the habit at a young age have markedly different brain structures, a study shows.
A research team at the University of California - Los Angeles (UCLA) used magnetic resonance imaging (MRIs) to map the brains of 42 young adults, aged 16 to 21, while documenting their smoking history, habits, and cravings. Of the participants, eighteen were regular smokers.
Published in Neuropsychopharmacology, the study initially found that differences between the brains of smokers and non-smokers were minimal. However, on closer inspection, heavier smokers (compared to those who smoked fewer cigarettes) were found to have generally thinner insulas - an area of the cerebral cortex that impacts the decision making process. The insula also has the most nicotine receptors found in the cortical - or memory - section of the brain. The findings were particularly interesting as they were drawn from subjects with comparatively short smoking histories, thus indicative of how quickly the brain can become dependent on nicotine and tobacco. "Because the brain is still undergoing development, smoking during this critical period may produce neurobiological changes that promote tobacco dependence later in life," said the study's lead author, Edythe London.""It is possible that changes in the brain from prolonged exposure help maintain dependence."
The study doesn't clarify if the differences in insula thickness are a result of smoking, or rather signify an established predisposition to smoking. However, it does recognize the insula as a crucial region of the brain in understanding the effects of nicotine dependency. "I think this is very exciting because it points to a vulnerability, a potential vulnerability factor either to become nicotine dependent or for the effects of smoking to ultimately alter the trajectory of brain development," said London.
The sentiment is reinforced by Dr. Nasir H. Naqvi, a substance abuse specialist at New York's Columbia University, who is not associated with the study. "It is possible that such changes pre-dated the smoking, i.e. they were not caused by smoking," Dr. Nasir H. Naqvi wrote in an email to Reuters Health. "The only way to know this is to take a group of adolescents who have never smoked, follow them over time, and then see who starts smoking, and then compare them to the adolescents who never started smoking."
