Discoveries

Movie scenes serve as signals to smoke

By Lauren Arcuri

These are stills from Matchstick Men, which was used in a study analyzing brain activity in smokers.

Smokers who are trying to quit know to avoid people and places likely to remind them of their habit. But now a study in the Journal of Neuroscience shows that simply watching actors smoke on-screen may induce an urge to light up, by activating regions of the brain associated with both the reward system and the physical act of smoking.

The study, conducted in the lab of Dartmouth's Todd Heatherton, Ph.D., provides new insights into an area of psychology called cue reactivity; its focus is how people react when exposed to cues associated with a behavior they are trying to regulate, such as smoking or overeating. DMS's James Sargent, M.D., a coauthor of the study, had previously found that the more smoking there is in a movie, the more smokers report craving a cigarette after watching it. Sargent and Heatherton wanted to explore this phenomenon more deeply.

Scenes: To find out what happens in smokers' brains when actors smoke on-screen, Heatherton and graduate student Dylan Wagner designed a study showing scenes from the 2003 movie Matchstick Men, which has a lot of smoking in it but not a lot of other potentially confounding actions, such as violence. They measured the brain activity of both smokers and nonsmokers using functional magnetic resonance imaging (fMRI).

The participants did not know that smoking was the subject of the research. "We thought it was important for the participants not to know what the study was about," says Heatherton, lest that knowledge alter the results.

Area: Compared to nonsmokers, smokers showed greater activity in an area of the brain called the reward region, which is associated with cue reactivity. Smokers also showed greater activity in areas associated with the motor actions of smoking. "This was really interesting and a bit of a surprise," says Heatherton. "You're getting a double whammy—both the reward system that says it would be good to have a cigarette and the motor systems are now active. It's like sharing a cigarette with the actor."

The results have important implications. "One of the things that we know causes problems for people trying to control a behavior, like smoking, is exposure to cues associated with that behavior," says Heatherton. So, if smokers trying to quit were aware that just watching someone smoke in a movie might increase their urge to smoke, they could try to avoid such situations.

Cue: The next step will be linking the brain activity the study showed to real-world behavior. For example, does the degree of someone's cue reactivity predict how successful the person is at giving up smoking? And what brain systems are involved in overriding the cues? Heatherton's group is already seeking answers to these and other questions.