It’s well established that smoking affects the male brain one way and the female brain another. New research at Yale using movies produced by PET shows some of the key differences in action.

The videos show that dopamine—aka the “feel-good neurotransmitter”—goes to work much faster in men than in women with each inhalation, according to a study published online Dec. 10 in The Journal of Neuroscience. The images also show that the subregions of the brain in which the activity takes place vary by sex in consistent ways.

To arrive at their conclusive images, the researchers injected 16 participants, heavy smokers all, with a tiny amount of radioactive agent that lit up in the brain where dopamine levels were high. Then they captured real-time images using a fairly new image-analysis technique, linear parametric neurotransmitter PET (lp-ntPET), in scans that took about an hour and a half.  

In the study abstract, the authors note that their finding reinforces previous science showing that men tend to smoke for the effects of nicotine while women are more motivated by habit and the drive for stress relief.

They also suggest that the work may help lead to better-targeted approaches to smoking cessation.

“This is the first demonstration of differences in the brain’s response to smoking,” Evan Morris, senior author of the study and an associate professor of diagnostic radiology at Yale, told the Connecticut Health Investigative Team. He pointed out that previous studies have imaged smokers’ brains after they finished smoking, adding that the new study represents the first time a PET scan was used to provide a minute-by-minute record of how brains respond to smoking.

“What’s going to be really important with this new technology is that we’re not just looking at dopamine release as a whole,” Kelly Cosgrove, an associate professor of psychiatry, diagnostic radiology and neurobiology, told the Connecticut Health I-Team. “The   new use of PET scans can analyze specific aspects of how and where dopamine is released. That’s never been done before.”

Cosgrove stressed to the reporters that the study gives those developing smoking-cessation tools new insight into how to target them differently to men and women.

The timing of the study could hardly have come at a better time if it is to catch the attention of smokers. It followed just one week after researchers at Uppsala University in Sweden published a 6,000-participant study in the journal Science showing that male smokers lose Y chromosomes—which previously has been shown to put men at greater risk for lung cancer than women.

“Cigarette smoking is a major public health danger,” wrote the Yale authors, and they’re not exaggerating. The American Cancer Society estimates that 1 in 13 men in the U.S., and 1 in 16 women, develop lung cancer. The ACA website notes that, while these numbers include both smokers and non-smokers, the risk is much higher for smokers.

Meanwhile, just last month—after months of nail-biting leading up to decision day—Medicare finally approved low-dose CT for lung-cancer screening.

To access the Yale study, Sex Differences in the Brain’s Dopamine Signature of Cigarette Smoking, click here (subscription or purchase required).