Damage to the insula might cure cigarette addiction
“smokers with brain damage involving the insula … were more likely than smokers with brain damage not involving the insula to … quit smoking easily, immediately, without relapse, and without persistence of the urge to smoke” One subject reported that after his stroke, “my body forgot the urge to smoke”.
However, the subject did not lose the urge to eat. The researchers hypothesize that the function of the insular cortex is confined to learned desires.
However, the article says that “the likelihood of quitting smoking after a lesion in either the right or the left insula was not significantly higher than the likelihood of quitting after a noninsula lesion”. But actually, insula damage did make it more likely to quit, just not SIGNIFICANTLY more likely to quit (P = .1, not .05). These pie charts emphasize this point:
If you forgot where the insula is (I did), it’s part of the cortex that is hidden in the middle:
Apparently it’s been implicated in a zillion things, particularly somatosensory stuff, with emphasis on the “somato”, including awareness of one’s limbs, taste, volitional swallowing, pain (2), audition and language and speech, and also pulmonary, vestibular and cardiovascular stuff (2) and regulatory stuff, and also emotions (2) (3)(4), including romantic love (2). Also food craving, the urge to urinate, neuroticism, and economic decision-making (2). And, as the article points out, cocaine and cigarette craving (1), (2), (3). Reviews: (1), (2). Review (1) is suggested by Nasir Naqvi, the first author of the present study (and is cited in the paper).
Quoting a comment by Nasir below, the authors of the present study think that the “visceral sensory functions of the insula are key because of the visceral effects of smoking, such as effects in the airway and cardiovascular systems”. Elaborating on that, the paper speculates, “…much of the pleasure and satiety that is obtained from smoking is derived from its bodily effects … nicotine withdrawal is associated with changes in autonomic and endocrine function … evidence suggests that the insula …. [anticipates] the bodily effects of emotional events ….. The insula may therefore function in the conscious urge to smoke by anticipating pleasure from the airway effects of smoking and/or relief from the aversive autonomic effects of nicotine withdrawal.”
January 27th, 2007 at 8:52 pm
I am the author of this study. I read your take with interest. You correctly point out that insula-lesioned patients were more likely to, but not significantly so. I suspect that if we had a larger sample size this would have been significant. If you are interested in a review of insula function, I suggest Bud Craig’s 2002 Nature Reviews Neuroscience review. We think that the visceral sensory functions of the insula are key because of the visceral effects of smoking, such as effects in the airway and cardiovascular systems.
January 28th, 2007 at 3:04 am
Hi Nasir, it’s neat to have the author of the article responding to one’s weblog entry! I share your opinion that a larger sample size would probably have achieved significance, I hope my entry didn’t give another impression. Thanks for the review, I added it to the entry. I missed it because the word “insula” wasn’t in the title.
Incidentally, since the insula seems to be a rather big, do you have any hunches as to which area of the insula might be most involved?
January 29th, 2007 at 4:07 pm
As a student of addiction,i have read much on the importance of the dopamine uptake relationship noted in many addictive materials, mostly plant based alkaloids or their man made equivalents. Nicotine falls into this category, though apperently without the large dopamine receptor die off noted in users of methamphetamine and cocaine. I have noted some papers with references to dopamine (d2 ) receptor in the anterior insula, and some references to novelty seeking and receptors on the right side of the insula. perhaps you could suggest some further reading on these relationships? I also want to thank you for the excelent graphic presentation of the statistical results of Dr. Navqui’s study.such graphics are very usefull in education. Thank you for you time and I am delighted to have found your site and service.
L Alvis
January 29th, 2007 at 8:44 pm
Hello, Lou, I’m glad to hear that you liked it. You already know more about dopamine receptors in the insula than I do. Perhaps another reader can provide more information though. Also, would you like to post the references you have already found? You could post another comment, or, if you’d like, you can even post that as a main article — just follow the instructions under “how to post” at the top-right hand side of the page at http://neurodudes.com. Thanks,
bayle
February 7th, 2007 at 7:44 am
In response to the first few entries, I wonder whether a bilateral insular lesion would have produced more dramatic results, somewhat similar to prosopagnosia being best obsereved in patients with bilat lesions. Since there are adequate animal models of addiction, this might be worth investigating and moving away from the emphasis on the septal/NA region.
January 8th, 2010 at 1:07 am
As someone whom recently suffered a head injury that “messed me up” for about a week, and then lost the urge to smoke cigarettes completely, I find this new research very fascinating. How likely is it that my insula received some sort of damage? Has ease of smoking cessation been reported with other types of brain injuries?