Stroke Damage to Insular Cortex Boosts Smoking Cessation

Pauline Anderson

November 03, 2011

November 3, 2011 — Smokers who suffer a stroke that causes a lesion at the insular cortex are more than 5 times more likely to stop their nicotine habit than those whose stroke did not result in such a lesion, according to a new study.

In addition, the researchers found that preparedness to change also influenced successful smoking cessation poststroke.

The study results were not surprising, given that research has already shown that biological and psychological factors help explain smoking cessation in patients with stroke, said the study's lead author, Rosa Suňer Soler, PhD, from the Neurology Department, Josep Trueta Hospital, Girona, Spain.

Biologically, the insular cortex may play an important role in emotional decision-making, and in terms of psychology, smoking behavior may be explained by stages, processes, and levels of change, Dr. Suňer told Medscape Medical News. "Before you stop smoking, you must be aware that you have a problem and take the decision to stop smoking."

The study was published online November 3 in Stroke.

Lesion Location

The analysis included 110 patients who were smokers when they suffered an acute stroke and were admitted to a stroke unit between January 2005 and July 2007. Researchers recorded sociodemographic and other variables, as well as information on smoking, including number of cigarettes smoked per day and level of nicotine dependence. In addition, they categorized patients according to their stage of preparedness to quit smoking before the stroke: precontemplation, contemplation, preparation, action (stopped smoking for less than 6 months), or maintenance (smoke-free for at least 6 months)

From computed tomography or magnetic resonance imaging scans, investigators classified lesions affecting the insular cortex by hemisphere (right or left side) and subtype (ischemic or hemorrhagic) and measured the volume of the cerebral infarct or hemorrhage.

Patients were evaluated at 3, 6, and 12 months after the stroke. Smoking abstinence was confirmed by recording expired carbon monoxide levels. Patients also assessed their difficulty in giving up smoking and their urge to restart the habit.

Patients smoked on average 27.6 cigarettes per day, had a mean score of 6.1 points in the Fagerström Test of nicotine dependence, and had started smoking at a mean age of 17.1 years. Of the sample, 85.5% said that before the stroke, they were not considering stopping smoking in the near future.

In 24.5% of the patients, the stroke-related lesion affected the insular cortex. At discharge, 69.1% of patients indicated they had given up smoking during hospitalization, including 88.9% of the patients with an insular cortex lesion and 62.7% of those without (P = .05).

At 1 year, 70.4% of participants with insular cortex lesions had stopped compared with 30.1% of those without (P < .001).

Having a lesion at the insular cortex was associated with significantly increased odds of quitting smoking (odds ratio, 5.42; 95% confidence interval, 1.95 - 15.01; P = .001).

According to Dr. Suňer, the insular cortex may regulate the experience of conscious urges and cravings with other specific brain areas. Disruption of hypocretin transmission in the insular cortex may also help explain decreased tobacco consumption in smokers with damage to this brain region, she added.

Having the intention to stop smoking before the stroke also increased the odds of successfully quitting the habit (odds ratio, 7.29; 95% confidence interval, 1.89 - 28.07; P = .004). In addition, patients who stopped smoking had a lessened perception of difficulty in stopping smoking.

"Considering our results, we must adjust therapeutic interventions to stages of change in patients" and help them to quit if they have raised a concern about smoking, said Dr. Suňer. She suggested that physicians systematically ask patients who smoke what stage they are at in terms of quitting.

Smoking Dangers

The study also showed that only a third of the patients associated stroke with their smoking habit. "It shows how little knowledge people have of the true dangers of smoking," said Dr. Suňer. "We explain to our acute stroke patients the risk factors and the importance of prevention, but there must also be more information campaigns among the general population."

As well as emphasizing this lack of awareness that smoking is a stroke risk factor, the study also highlights the fact that willingness and consideration to stop the habit before the stroke help patients quit afterward, said Joseph Broderick, MD, chair of neurology, University of Cincinnati, Ohio, and a member of the American Academy of Neurology, when asked to comment.

"It is also remarkable that despite a life-changing event such as a stroke, so many patients continue to smoke," Dr. Broderick told Medscape Medical News.

Dr. Broderick questioned whether language disruption, which often accompanies insular damage in the dominant hemisphere, plays a role in smoking cessation.

"The volume of brain injury was similar for the smokers and those who successfully stopped," he noted. "I wonder whether language impairment per se could be associated with increased likelihood of stoppage, rather than an effect upon emotional and reward processing in the brain."

The authors have disclosed no relevant financial relationships.

Stroke. Published online November 3, 2011.

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