By analyzing dynamic brain scans, Yale researchers have pinpointed a different brain response between male and female smokers, a finding that could lead to breakthroughs in developing gender-specific treatments to help smokers quit.
The study, published today in The Journal of Neuroscience, measured in a new way how and where nicotine affects pleasure receptors in the brain, according to Evan Morris, senior author of the study and an associate professor of diagnostic radiology, biomedical engineering and psychiatry at Yale University.
Previous research has shown smoking cigarettes affects men’s and women’s brains differently, but this study marks the first time that PET (positron emission tomography) scans were used to create “movies” of how smoking affects dopamine, the neurotransmitter that triggers feelings of pleasure in the brain, Morris, the Co-Director of Imaging Section, Yale PET Center, said.
Movies were made of 16 addicted smokers’ brains, eight men and eight women. Each smoked their cigarette of choice while undergoing a PET scan that lasted about 90 minutes. The movies show that smoking affects the dopamine in the brain differently – at different rates and in different locations – depending on whether the person is male or female, the researchers say.
“This is the first demonstration of differences in the brain’s response to people smoking,” Morris said, noting previous studies have taken images of smokers’ brains after they had smoked. This is the first time a PET scan was used to provide a minute-by-minute record of how brains responded; past research has tracked hourly averages and produced less detailed findings, he said.
The videos show that dopamine is activated by smoking in men much faster than it is in women. Participants were injected with a very small amount of a radioactive molecule that “lit up” parts of the brain where high levels of dopamine were present.
“They are equally dependent (on nicotine) but their brains are responding differently. This is not an event that could have happened by chance,” Morris said.
The finding can be extremely useful when it comes to developing gender-specific methods to help smokers quit, said Kelly Cosgrove, lead author of the study and an associate professor of psychiatry, diagnostic radiology and neurobiology at the Yale School of Medicine.
The study gives those developing smoking-cessation tools new insight into how to target them differently to men and women, she said.
Past research has shown behavioral differences when it comes to male vs. female smokers. For decades, men have had better luck quitting by using medications and nicotine blockers such as patches. That is because men smoke for the effect of nicotine level, studies have shown, while women typically smoke to relieve stress or out of habit.
The new study reinforced that previous research, Cosgrove said. It found dopamine release in nicotine-dependent men occurred quickly in an area of the brain that reinforces the effect of drugs such as nicotine. Women had a similarly rapid response but in a different part of the brain, the one associated with habit formation.
Before this study, the neurological basis for the differences between the genders had eluded researchers, according to Yale. The finding is the culmination of about three years’ worth of research, Morris said.
“What’s going to be really important with this new technology is that we’re not just looking at dopamine release as a whole,” Cosgrove said, adding the new use of PET scans can analyze specific aspects of how and where dopamine is released. “That’s never been done before.”
The effect could be far-reaching. Though strides have been made in helping people quit, smoking continues to be a major health issue. Cigarette smoking is responsible for more than 480,000 deaths nationwide each year, according to the U.S. Centers for Disease Control and Prevention.
Smoking causes 90 percent of all lung cancer deaths and 80 percent of all chronic obstructive pulmonary disease deaths, and more than doubles the risk of getting heart disease or having a stroke. Men who smoke are 25 times more likely than nonsmokers to get lung cancer, while female smokers are 26 times more likely to get it than their nonsmoking counterparts, according to the CDC.
The Yale study was supported by the National Institute on Drug Abuse and the National Institutes of Health Office of Research on Women’s Health, through the Yale Translational Center to Develop Gender-Sensitive Treatment for Tobacco Dependence.