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Younger smokers might suffer the most consequences from cigarettes since they tend to smoke more often than any other age group within the United States. Since many studies have examined the effects of smoking on health conditions, such as lung and heart disease, a new study set out to examine another part of the body that could be affected by smoking: the brain. The researchers from the University of California Los Angeles discovered that the brain structure of young smokers appears to change as exposure to cigarettes continues to increase.

"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, 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."

For this small study, London and her team recruited 42 participants who were between the ages of 16 and 22. 24 of them were non-smokers and 18 of them were current smokers. The smokers had picked up the habit at around the age of 15 and smoked less than seven cigarettes per day. The researchers took high-resolution structural magnetic resonance imaging of the participants to measure the cortical thickness of the insula.

The researchers discovered that for every additional "pack-year," which represented cigarette exposure, the individuals' cortical thickness on the right side of the insula became thinner. When the researchers assessed the participants' dependence on cigarettes and their urge to smoke, they found that same relationship.

"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 reported in the news release. "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."

The study was published in Neuropsychopharmacology.