Stroke brain damage could reveal key to treating addiction

8 Sep

New research has found that smokers who had a stroke in a brain region called the insular cortex were more likely to quit smoking than those who had strokes in other regions of the brain. The research has led scientists to conclude this region could be crucial in treating addiction.

Image of a skull indicating a stroke.
Active smokers who had strokes in the insular cortex region of the brain were more likely to quit smoking than smokers who had strokes in other regions of the brain.

Smokers who had strokes in the insular cortex also did not experience as many withdrawal symptoms as those who had strokes in other regions of the brain.

This new research takes the form of two studies that are published in the journals Addiction and Addictive Behaviors, respectively.

“These findings indicate that the insular cortex may play a central role in addiction,” reports lead author Amir Abdolahi, a clinical research scientist at Philips Research North America. “When this part of the brain is damaged during stroke, smokers are about twice as likely to stop smoking and their craving and withdrawal symptoms are far less severe.”

According to the Centers for Disease Control and Prevention (CDC), cigarette smoking is the leading cause of preventable disease and death in the US, accounting for more than 480,000 deaths every year.

Due to the addictive qualities of nicotine, it can be difficult to quit smoking once it has become a habit. While smoking rates have fallen in recent years, from approximately 21 of every 100 adults in 2005 to 18 of every 100 adults in 2013, cigarette smoking is still behind 1 in every 5 deaths in the US.

At present, prescription drugs that are used to help people quit smoking work by disrupting “reward” pathways in the brain that respond to nicotine. Unfortunately, this form of treatment has a high rate of smoking relapse, with an estimated success rate of up to 30% after 6 months. Nicotine patches and lozenges have a similar rate of success.

Previous studies have suggested that the insular cortex region of the brain could play a significant role in the cognitive processes that enable drug use. It is unclear, however, as to whether changes in this region of the brain have any effect on drug use.

To investigate, the researchers set out to discover whether smokers who had suffered damage to the insular cortex from a stroke were more likely to quit smoking than smokers with acute damage to other regions of the brain.

Around 70% of insular cortex stroke patients quit smoking after 3 months

The two studies measured two different indicators of smoking cessation likelihood: how severe their cravings were during hospitalization from their stroke and whether or not they resumed smoking following their stroke.

A total of 156 patients with stroke were assessed in the study, all of whom were active smokers. The researchers determined the locations of their strokes using magnetic resonance imaging (MRI) and computed tomography (CT) and divided the patients into those whose strokes occurred in the insular cortex (38 patients) and those whose strokes occurred elsewhere (118 patients).

Fast facts about nicotine

  • In the US, more people are addicted to nicotine than any other drug
  • Some studies suggest nicotine may be as addictive as alcohol, cocaine or heroin
  • Nicotine withdrawal symptoms include feeling irritable, lack of concentration and hunger.

Learn more about nicotine

After measuring multiple aspects of withdrawal during hospitalization, the researchers found that the patients who had strokes in the insular cortex experienced fewer and less severe withdrawal symptoms compared with the patients whose strokes occurred in other brain regions.

The researchers also followed up the patients 3 months after their strokes, assessing their self-reported smoking status and any abstinence from nicotine products.

They found that while 37% of patients with strokes in other parts of the brain had quit smoking, 70% of the patients with strokes in the insular cortex had.

Although the studies involved a relatively small number of patients who experienced damage to the insular cortex, the researchers believe these findings support the potential role of this area of the brain in maintaining smoking and nicotine abstinence.

“Much more research is needed in order for us to more fully understand the underlying mechanism and specific role of the insular cortex, but is clear that something is going on in this part of the brain that is influencing addiction,” Abdolahi concludes.

Previously, Medical News Today reported on a study investigating a new type of anti-smoking therapy. In the study, researchers assessed a bacterial enzyme that consumes nicotine “like a little Pac-Man” that may be able to prevent the drug from reaching the brain.

Written by James McIntosh

Copyright: Medical News Today

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