Brain Region That Fuels Addiction Found

Study reveals that those with damage to the insula quit smoking easily

By Amanda Gardner
HealthDay Reporter
Thursday, January 25, 2007; 12:00 AM

Copyright © 2007 ScoutNews, LLC. All rights reserved.

THURSDAY, Jan. 25 (HealthDay News) -- A small area of the brain nestled inside the cerebral cortex might explain why smoking is such a hard habit to break.

A new study of 69 smokers with brain injuries showed that those who had damage to the insula often quit smoking suddenly and effortlessly, suggesting that this particular area could be a target for future therapies to help smokers quit.

"This is the first study to show in humans that there's a brain area that's somehow necessary to promote addiction to any drug, and smoking in particular," said study author Dr. Nasir Naqvi, a doctoral student in the medical scientists' training program at the University of Iowa Carver College of Medicine. The report is published in the Jan. 26 issue of Science.

"This is a seminal paper," said Deborah Mash, a professor of neurology at the University of Miami Miller School of Medicine. "However, the fundamental question is whether the effect is specific to nicotine, because it may be that the insula is the seat of the soul for the compulsive taking of all abused substances."

The study was prompted by the experience of one patient, a two-pack-a-day smoker who quit immediately after his insula was damaged by a stroke. His body "forgot the urge to smoke," he told researchers.

The insula's function seems to be to take information from other parts of the body and translate that into feelings such as fear, disgust, anger and sadness, along with desires and cravings.

Although some imaging studies have shown that this region of the brain is activated by drug-related cues, "the insula has never really been examined closely for its role in addiction," Naqvi said.

Naqvi and his colleagues found 69 additional patients with brain damage, all of whom had been smokers before the damage occurred. Nineteen of the participants had brain damage involving the insula, 13 of these had quit smoking, and 12 of them had done so quickly and easily.

While some of the other patients also quit smoking, those with damage to the insula were more likely to have quit immediately and without anguish.