Addictions are hard to kick. Just ask all cigarette smokers who keep puffing away despite the boatload of evidence that they are killing themselves.

Now, new research being conducted in Israel shows that addictions work differently in women and men. A study being conducted largely in Israel by Evan Morris, an associate professor of Radiology, Biomedical Engineering, and Psychiatry at Yale University, shows this clearly. In fact, Morris and his students have even made a movie out of it.


“Our dopamine movies show the effect of nicotine on the dopamine levels in the body, and those movies – which essentially show how the brain reacts when the chemical is released – shows clearly that there is a difference in brain activity for men and women who smoke.”

Those findings are interesting, Morris told The Times of Israel, but the real point is to show “how short-term bursts of brain activity are prompted by chemical changes. This could have all sorts of implications for treating symptoms like PTSD and other stress-induced conditions, where there can be radical changes in brain activity for short periods of time.”

Morris is a world-renowned expert on Positron Emission Tomography (PET) imaging using tracer kinetic modeling to create functional images of the brain.

“With PET, you can see in how the brain changes – based on mathematical formulas – in response to induced changes,” said Morris. “One of the most difficult challenges facing researchers is developing models of short-term changes – changes in the brain that pass quickly, perhaps in just a few minutes or so.”

It’s clear that with a supercharged emotion taking over the body – anger, ecstasy, or anything in between – there are changes to the brain, “but generally researchers have been able to capture only changes that linger, with the imaging of the short-term changes unattainable.”

That’s what makes a study of smoking so attractive. “When a person smokes, the chemicals they inhale – especially nicotine – engender a response that releases dopamine, the brain’s primary motivation neurotransmitter.”

Dopamine is released in response to environmental and internal stimuli – food, sex, or pleasurable events – as well as in response to chemicals that stimulate the central nervous system, like nicotine.

The sensation involved with nicotine – as with other drugs – is fleeting, with dopamine levels rising sharply but briefly. PET scans, said Morris, provide an opportunity to see how this fleeting sensation physically affects the brain.

“We are able to scan the brain’s reaction using a tracer that mimics dopamine. With our method, we are able to see how brains react to the chemically induced changes associated with addiction over time, creating a movie which shows the changes – and that is where we noticed how male and female brains differ when it comes to smoking.”

Dr. Evan Morris (Courtesy)

Dr. Evan Morris (Courtesy)

The results of the study, which was largely carried out at Hadassah Ein Kerem Hospital in Jerusalem with Dr. Nanette Freedman of the Nuclear Medicine Dept., were published in a recent edition of the Journal of Neuroscience.

The findings, according to the report, show that “male smokers smoking in the PET scanner activate dopamine in the right ventral striatum during smoking but female smokers do not. This finding—men activating more ventrally than women—is consistent with the established notion that men smoke for the reinforcing drug effect of cigarettes whereas women smoke for other reasons, such as mood regulation and cue reactivity.”

Based on these results, said Morris, who collaborated on developing the method with Yale co-researcher Prof. Kelly Cosgrove, researchers will be better able to understand what makes smokers tick – and develop more effective ways to get them to kick the habit. “It could be, for example, that you need different kinds of nicotine patches designed for men and women, since they react differently to nicotine.”


But besides what the study means for smokers, it also has implications far beyond nicotine addiction.

“Any short-term event that affects the brain could be ‘filmed’ for analysis, to see which part of the brain is affected, and how,” added Morris.

Just like adrenaline flows in a moment of danger providing extra strength in a moment of need, brain changes in response to those dangers could teach researchers about how people think and react – and how to “turn on” parts of the brain that can enhance thinking, among other things.

“PTSD, ADHD, and other conditions in which an individual’s mood and actions change depending on stimuli could be better understood using this method,” said Morris.

Morris, an associate professor of diagnostic radiology, biomedical engineering and psychiatry at Yale University, is in Israel on a Fulbright exchange program scholarship, which each years brings dozens of American researchers to Israel to work on innovative medical and technology projects in the start-up nation for a year, while sending Israeli researchers to work in the US for the same amount of time.

One reason Morris chose Israel is that he needed a young adult population that had recently taken up smoking in order to find recently addicted people.

“Part of what we are trying to determine is the development of addiction. Are there people more prone to addiction?” he said. “To see that kind of progression, you want people who are recent smokers so you can see over time what their brain patterns are, and how they change the more they are exposed to the cause of their addiction.

“In the US, most of these early stage smokers are kids – under 18 years of age, study of which entails all sorts of legal and disclosure issues. In Israel, many of the young smokers pick up the habit in the army – so they are already over 18, and it is much easier legally to recruit them for studies like these, that entail using the radioactive material we need for the PET tracer,” he added.

Morris will be discussing this and other findings of his research, along with other uses and research being conducted with PET, at a special event at Hadassah Ein Kerem Hospital on February 29, in a one-day symposium on Advances in Brain Imaging. The symposium is funded by Fulbright, Yale, Hadassah, and the US National Institutes of Health, which is also helping to fund Morris’s Hadassah research.

“Smoking was a good place to start, but we certainly don’t intend to stop there. The movies we created showing brain changes induced by stimuli can ‘star’ many more chemicals besides dopamine, giving us more insight into how the brain works.”

Times of Israel website