By Steve Tokar | ucsf.edu | July 27, 2012
The brains of adolescents who smoke as little as two cigarettes a day respond to images of smoking as do the brains of heavily addicted adult smokers: with pleasure.
A study by UCSF’s Mark Rubinstein, MD, finds that the threshold for nicotine addiction in teenagers might be much lower than is commonly believed.
“Most smoking cessation programs require that you smoke at least ten cigarettes per day,” says Rubinstein, associate professor and adolescent medicine specialist in the Department of Pediatrics at UCSF’s School of Medicine. “Below five [cigarettes per day], it’s very controversial as to whether you are even addicted, even if you are smoking daily.”
For the study, which was supported by an award from the Strategic Opportunities Support (SOS) program of UCSF’s Clinical and Translational Science Institute (CTSI), Rubinstein recruited a group of teenagers who smoked fewer than five cigarettes per day, and a matched group of adolescent non-smokers.
He used functional magnetic resonance imaging to monitor which regions of the teenagers’ brains were activated when viewing a random assortment of smoking imagery — someone holding a cigarette, for example — and neutral imagery — someone holding a pen. Rubinstein focused on the mesolimbic dopamine system, a network of neural pathways involved with pleasure, reward, and addiction.