A team of scientists has identified brain circuitry that is responsible for the increased anxiety in smoking cessation.
Principal investigator Andrew Tapper said that they identified a novel circuit in the brain that becomes active during nicotine withdrawal, specifically increasing anxiety, which is a prominent nicotine withdrawal symptom that contributes to relapse in smokers attempting to quit.
University of Massachusetts Medical School and The Scripps Research Institute's study yielded several discoveries about interconnected brain mechanisms that induce anxiety during nicotine withdrawal and possible ways to derail these mechanisms in order to treat or even prevent the especially troublesome symptom.
The study's main finding is that a brain region called the interpeduncular nucleus is activated and appears to cause anxiety during nicotine withdrawal. It also found that the sub region of the interpeduncular nucleus, which is activated and linked to anxiety during withdrawal, is distinct from another sub-region, previously identified by Tapper, where physical nicotine withdrawal symptoms such as headaches, nausea and insomnia originate.
The newly discovered sub region offers a distinct target for dampening the affective symptoms of nicotine withdrawal and also newly identified is the fact that input from neurons in two other brain regions converges onto the interpeduncular nucleus to stimulate anxiety-provoking neurons.
Investigators were able to alleviate anxiety in mice by quieting the activity of those activated neurons, suggesting the same might be possible for humans.
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Tapper noted that there are already drugs that block the CRF receptor that contributes to activation of these anxiety-inducing neurons and these receptors have previously been linked to anxiety and depression, so their findings may also have implications for anxiety disorders in general.
The study is published online by Nature Communications.