Brain structure is changed in people who smoked tobacco as teenagers, according to researchers.
The study was conducted by teams from UCLA and the David Geffen school of Medicine, in Los Angeles. Edythe London headed the research.
A total of 42 people, aged 16 to 21, had their brains mapped by magnetic resonance imaging (MRI). Of the subjects participating in the study, 18 were smokers, consuming an average of six or seven cigarettes a day. Most had started by the age of 15. Each of the subjects was asked about their history of smoking, including how often they craved nicotine.
Tobacco damaged or killed brain cells in adolescent animals, the study revealed. The right insula, a region of the cerebral cortex associated with decision making, was found to be thinner in those who smoked, compared to non-smokers. The area of the human brain contains the greatest concentration of nicotine receptors of any region. Similar changes were notices among participants reporting severe cravings and feelings of dependence. It is possible the thinner structure provides diminishing control over cravings.
People who start tobacco use early in life usually experience greater trouble kicking the habit, and suffer from a greater incidence of serious disease than those who start when they are older.
Research found changes in brain structure and behavior were far different in heavy smokers than in people who smoked lower quantities of the drug.
"It is possible that such changes pre-dated the smoking, i.e. they were not caused by smoking. 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," Nasir Naqvi, a substance abuse researcher, wrote to Reuters Health in an email.
"Although the results do not demonstrate causation, they do suggest that there are effects of cigarette exposure on brain structure in young smokers, with a relatively short smoking history. It is possible that changes in the brain due to prolonged exposure or to the progression of dependence lead to more extensive structural changes, manifested in the reported group differences between adult smokers and nonsmokers," the researchers wrote in the article announcing the results.
Even though the sample size was small, the researchers believe the results call for additional studies.
Tobacco company Phillip Morris funded the study. They had no input into the construction of methodology of the research.
Details of the study were published in the journal Neuropsychopharmacology on 3 March.
