New Study Finds Brain Chemical May Be Responsible for Sadness When Heavy Smokers Quit
Anecdotally, we’ve known for years that people who try to quit after being heavy smokers often feel bouts of sadness. Now, the results of a new study may have found the reason why.
Researchers for the Center for Addiction and Mental Health (CAMH) have found that an increase in the mood-related brain protein monoamine oxidase A (MAO-A), occurs after early withdrawal in heavy smokers. The finding, which was recently published in the Archives of General Psychiatry, may further help to explain why heavy smokers are at high risk for clinical depression.
Advanced Brain Imaging Used in the Study
The research team, led by senior scientist Dr. Jeffrey Meyer, used an advanced brain imaging method to discover that MAO-A levels in the brain regions responsible for controlling mood rose by 25 percent eight hours after withdrawal from heavy cigarette smoking.
Researchers found that these levels were considerably higher than in a comparison group of non-smokers also participating in the study. All 48 study participants filled out questionnaires. Smokers with high brain MAO-A levels during smoking withdrawal also reported greater feelings of sadness.
Sadness is Why it’s So Hard to Quit
When heavy smokers try to quit, but continue to feel sad, it’s undoubtedly a big contributing factor to why they find it so hard to remain non-smokers.
"Understanding sadness during cigarette withdrawal is important because this sad mood makes it hard for people to quit, especially in the first few days," said Dr. Meyer, who holds a Canada Research Chair in Neurochemistry of Major Depression. "This is the first time MAO-A, a brain protein known to be elevated in clinical depression has been studied during cigarette withdrawal."
How MAO-A Works to Cause Sadness
MAO-A literally consumes chemicals in the brain, such as serotonin, that help a person maintain a normal mood. During early cigarette withdrawal, MAO-A levels are higher, meaning that this removal process is overly active – and makes people feel sad.
The MAO-A was detected using the brain imaging technique called positron emission tomography (PET). Of note is that CAMH has the only PET scanner in the world that is dedicated solely to mental health and addiction research.
Researchers say that a specific substance in cigarette smoke, called harman, may be responsible for these changes. Harman attaches to MAO-A during active smoking. Among heavy smokers (those who had 25 or more cigarettes a day) who were in early withdrawal, MAO-A levels rose rapidly to a level beyond that seen in the healthy comparison group of non-smokers.
What the Findings May Mean for the Future
The study findings may point to new ways to prevent sad mood during cigarette withdrawal, principally as a means to make it easier for heavy smokers to quit. Dr. Meyer notes that it could be possible to improve existing cigarette filters to partially screen out harman, or to regulate the amount of tryptophan in cigarettes. Tryptophan, incidentally, becomes harman when it burns.
Dr. Meyer, who is also the head of the Neurochemical Imaging Program in Mood Disorders at CAMH’s Research Imaging Center, and a professor of psychiatry at the University of Toronto, adds that, "We also identified MAO-A as a target to shut down during the early critical stage of withdrawal with a short course of medication, but this requires further study."
Funding for the study came from the Canadian Institutes of Health Research’s (CIHR’s) Institute of Neurosciences, Mental Health and Addiction. Other support came from the Ontario Mental Health Foundation, the Canada Foundation for Innovation, and the U.S.-based Brain and Behavior Fund (formerly NARSAD).
