A new study by researchers at UCLA finds that cigarette cravings and dependence may cause structural changes in the brains of young smokers, including those who have only been smoking for a short time. The neurological changes may help explain why people who begin smoking at a young age can become addicted to cigarettes.
“Although we are not certain whether the findings represent the effects of smoking or a genetic risk factor for nicotine dependence, the results may reflect the initial effects of cigarette smoking on the brain,” said Edythe London, Ph.D., senior author of the study and a professor of psychiatry and of molecular and medical pharmacology at UCLA’s Semel Institute for Neuroscience and Human Behavior and the David Geffen School of Medicine. “This work may also contribute to the understanding of why smoking during this developmental stage has such a profound impact on lifelong smoking behavior.”
The study authors found differences between younger smokers and non-smokers in the insula, a part of the brain’s cerebral cortex that is involved in making decisions. The researchers studied the insula because it has the highest density of nicotinic acetylcholine receptors within the human cerebral cortex and is known to play a key role in maintaining tobacco dependence. The researchers conducted the study by taking smoking histories, assessing cigarette craving and dependence, and examining the insula through high-resolution structural magnetic resonance imaging (MRI) in 42 participants ages 16 to 22. Of the participants, 24 were non-smokers and 18 were smokers. Those who smoked began around the age of 15 and smoked fewer than seven cigarettes a day at the time of the study.
The researchers measured cortical thickness of the insula in both groups and found that the more someone smoked the thinner the insula and the greater the cigarette craving and dependence.
“Our results suggest that participants with greater smoking exposure had more severe nicotine dependence, more cigarette craving and less insular thickness than those with less exposure,” London said. “While this was a small study and needs to be replicated, our findings show an apparent effect of smoking on brain structure in young people, even with a relatively short smoking history.”
London says the findings are concerning. “It suggests that smoking during this critical time period produces neurobiological changes that may cause a dependence on tobacco in adulthood.”
The study was published in the journal Neuropsychopharmacology. Funding for the study was provided by Philip Morris USA, a maker of many cigarette brands, but according to UCLA, “Philip Morris did not have any input on the design of the studies, data analysis or interpretation.”