Young adults who smoke cigarettes, even for a short amount of time, may be changing the structure of their brains, according to a University of California, Los Angeles (UCLA) study. These findings could explain why adults who began smoking at a young age stay addicted to cigarettes.
The study appears in the March 3 online edition of the journal Neuropsychopharmacology.
“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 senior author Edythe London, Ph.D., a professor of psychiatry and of molecular and medical pharmacology at UCLA’s Semel Institute for Neuroscience and Human Behavior and 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.”
London and her team, including first author Angelica Morales, a graduate student researcher in London’s lab, found differences in the insula, a part of the brain already known to play a central role in tobacco dependence. It has the highest density of nicotinic acetylcholine receptors within the human cerebral cortex.
The 42 study participants (ages 16-22) reported their smoking histories and their cigarette craving and dependence tendencies; overall, 24 were non-smokers and 18 were smokers.
Researchers then examined the insula using high-resolution structural magnetic resonance imaging. Those who smoked began around the age of 15 and smoked fewer than seven cigarettes a day at the time of the study.
By measuring the cortical thickness of the insula in both smokers and non-smokers, the researchers found that the number of years a person smoked was negatively related to the thickness in the right side of the insula. In other words, the more a person smoked, the thinner that part of the insula. The relationship also held true for the young adult’s level of dependence on cigarettes and the urge to smoke.
“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. And that is a concern. It suggests that smoking during this critical time period produces neurobiological changes that may cause a dependence on tobacco in adulthood.”