Structural brain changes of smoking in teens

It’s common knowledge that smoking cigarettes is bad for your health, but young people ages 18 to 25 are still choosing to light up more than any other demographic in the United States. Researchers at UCLA (University of California, Los Angeles) now have evidence that young smokers who have smoked more cigarettes have clear differences in their brains compared to non-smokers.

The study was published on March 3rd in the journal Neuropsychopharmacology and was funded by Philip Morris USA, makers of Marlboro and Virginia Slims.

Prior research has shown brain differences between adult smokers and non-smokers, but few studies focused on the youngest human demographic of smokers whose brains are still undergoing development. In studies of adolescent animals, nicotine damaged and killed brain cells.

The UCLA researchers team mapped the brains of 42 people ages 16 to 21 using magnetic resonance imaging (MRI) and asked them about their smoking history and cravings. Eighteen of the participants were smokers. They had typically started smoking around age 15 and smoked six to seven cigarettes per day.

There were no clear differences in the brains of smokers versus non-smokers. However, among smokers, those who reported smoking more cigarettes tended to have a thinner insula, a region of the cerebral cortex involved in in shaping our consciousness and emotions. The insula also houses a high concentration of nicotine receptors and plays a critical role in generating the craving to smoke. The effects seemed confined to the right insula.

The study’s lead researcher Edythe London, from the Semel Institute for Neuroscience and Human Behavior at UCLA and the David Geffen School of Medicine in Los Angeles, said they focused on this particular part of the brain because previous studies in adults and mice showed its size and volume were affected by smoking.

The researchers also found a thinner insula in the brains of people who had more cravings and felt more dependent on cigarettes. “Because the brain is still undergoing development, smoking during this critical period may produce neurobiological changes that promote tobacco dependence later in life,” said London. Changing the structure of the insula may affect future smoking dependence and other substance abuse.

London said It is possible that changes in the brain from prolonged exposure help maintain dependence,“ and added “People who start smoking early in life seem to have more trouble quitting and have more serious health consequences than those who start later”.

Although the study illustrated a difference in brain structure of young smokers and nonsmokers, it did not prove that cigarettes changed their brains. It could be that people with differently structured insulas are more likely to take up smoking for an unknown reason. However, the results pave the way for future studies to determine the actual cause and effect.

“Ideally one would start the study in 12-year-olds who haven’t begun to smoke; follow them out after they begin to smoke; and see if in fact the smaller insula thickness was a predictor of a predilection to become a smoker,” London said. “This is practical. It just requires funding.”

On the other hand, if London’s team finds proof that smoking causes thinning of the right insula, it would provide further evidence of the detrimental health effects of picking up the habit at a young age.