Has nicotine addiction finally met its match?
Smoking is one of the most harmful habits to adopt because it can cause lung cancer, heart disease and several other dire health problems. Nevertheless, over 22% of the world’s population uses tobacco, according to the World Health Organization, with more than 8 million people dying from it annually.
Roughly half of US adult smokers try to quit each year but usually less than 10% actually succeed — mostly due to troubles managing the intense cravings and withdrawal symptoms.
The US Food and Drug Administration has approved two medicines designed to help reduce tobacco cravings — bupropion (marketed as Wellbutrin) and varenicline (Chantix).
Now, scientists in Korea have discovered that the Parkinson’s disease drug procyclidine can alleviate physical symptoms of nicotine withdrawal, such as tremors and decreased mobility.
“This study presents new possibilities for smoking cessation treatment by mitigating the disruptions caused by withdrawal symptoms,” said Heh-In Im of the Center for Brain Disorders of the Korea Institute of Science and Technology. “It provides an additional treatment option alongside bupropion and varenicline.”
Parkinson’s patients have an imbalance between the neurotransmitters acetylcholine and dopamine within the striatum, a part of the brain deeply involved in movement control and processing rewards.
The depletion of dopamine is the primary cause of the motor symptoms associated with Parkinson’s.
Procyclidine works to restore the balance by blocking the activity of cholinergic interneurons, nerve cells that release acetylcholine. The drug treats muscle stiffness, tremors and spasms in Parkinson’s patients.
Im’s group found that giving a single low dose of procyclidine to mice exhibiting nicotine withdrawal symptoms reduced their tremors by over 50%.
The idea is that nicotine is structurally similar to acetylcholine, allowing it to bind to receptors on the cholinergic interneurons. The team’s experiments showed that suppressing the interneurons restored dopamine levels in the striatum.
Dopamine is known as the “feel-good” hormone, and the nicotine in cigarettes stimulates its release. Quitters often experience cravings because they miss the dopamine hit. Restoring dopamine would ease withdrawal.
“Moving forward, we aim to deepen our understanding of addiction mechanisms, including nicotine, and develop effective therapies,” Im said.
The results of Im’s study were published in November in the journal Advanced Science.
Since procyclidine is already approved in the US and other countries, the next step is to make sure that it doesn’t interact with established quit-smoking treatments and to see if the one-two punch can help people stop smoking for good.
