A study published in today’s edition of Science reports that nicotine addicted patients who acquired damage to the insula – an area just behind the temporal lobes – reported that the urge to smoke reduced after their brain damage occurred.
The insula is coloured red in the diagram on the right and has been heavily linked to emotional responses, particularly the perception and experience of disgust.
However, this new study, led by Nasir Naqvi, suggests that the insula is also heavily involved in addiction-related cravings.
Studying patients with brain damage is one of the most powerful methods in cognitive neuroscience.
While brain scans can tell you which areas of the brain might be associated with a particular experience or behaviour, they can’t tell you whether that area is necessary or not.
If you think a brain area might be crucial for a certain process, finding someone who has damage to that area should confirm whether your idea is correct or not by seeing whether they still have the ability or experience you think is linked to the area.
In Bechara and colleagues’ study, they included a series of patients who had insula damage, either after suffering a stroke, or after having it deliberately removed as part of brain surgery to treat epilepsy or brain cancer.
Because this sort of damage is rarely precise and causes damage to a number of areas in addition to the insula, a series of patients was studied.
While other damage was present, the patients only had insula damage in common.
This means when group results are analysed, the strongest overall effect should be related to insula damage, whereas effects from damage to other areas wouldn’t be as apparent, because it’s not common to all patients.
The researchers compared the group with insula damage to other smokers who had suffered non-insula brain damage by measuring who quit smoking, how strong the cravings were and how easy it was to give up.
Insula-damaged patients were much more likely to have quit smoking than the other patients, to experience less cravings, and to have found it easier to give up.
The researchers start their paper by noting that “cigarette smoking [is] the most common preventable cause of morbidity and mortality in the developed world”.
You can bet this study will cause massive interest in the pharmaceutical industry who will be attempting to work out the neurochemistry of the insula to try and create drugs which will make treating addiction easier.
Undoubtedly, education and prevention will be much cheaper, but it’s hard to make money out of people who don’t become addicted.
That’s progress for you.