Study reveals why some people 'born to smoke'

Irvine, Calif., February 12, 2004

Why are some people hopelessly addicted to cigarettes, while others seemingly can quit at will? A UC Irvine College of Medicine study reveals for the first time the underlying brain mechanisms that link personality traits to nicotine addiction.

It has been long established that hostile personality traits are related to cigarette dependency and smoking cessation difficulties. Now UCI researchers have found that in people who have aggressive personalities nicotine triggers significant brain activity in the areas that help control social response, thinking and planning. In turn, non-hostile people showed no brain activity increases at all to nicotine. These findings suggest that some people are born with a predisposition to cigarette addiction and helps explain why quitting for some is practically impossible.

"We call this brain response a 'born to smoke' pattern," said study leader Dr. Steven Potkin, professor of psychiatry and human behavior. "Based on these dramatic brain responses to nicotine, if you have hostile, aggressive personality traits, in all likelihood, you have a predisposition to cigarette addiction without ever having even touched a cigarette."

Study results appeared in the January issue of Cognitive Brain Research.

Potkin and Dr. James H. Fallon, professor of anatomy and neurobiology, gave study subjects standard psychiatric personality exams and separated them into two groups — those with high-hostility personality traits, which are marked by anger, aggression and anxiety, and those with low-hostility traits. Both groups included smokers and non-smokers. The groups were given nicotine patches of strengths of 3.5 or 21 milligrams, or placebo, and later subjected to PET scans to see if the nicotine triggered any responses in brain metabolism of glucose energy.

While the PET scans showed no metabolic changes in the low-hostility subjects, nicotine induced dramatic metabolic responses in the high-hostility group individuals in the limbic system and the cortical and subcortical sectors of the brain. Among members of the high-hostility group, smokers showed a metabolic reaction only to the more powerful 21 milligram nicotine patch, while non-smokers reacted to both patches.

The fact that non-smokers in the high-hostility group showed a significant metabolic response to nicotine provides the first biological evidence that people with high-hostility personalities are likely to become dependent on cigarettes because of their brains' strong response to nicotine, said Potkin. "In turn, this might also help explain why other people have no compelling drive to smoke or can quit smoking with relative ease," he added.

Potkin and his fellow UCI researchers are continuing their nicotine-PET scan study, looking into the role that gender and other traits may play in cigarette addiction.

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