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Addiction Gene Linked to Common Obesity



Hedonic hyperphagia (overeating controlled by reward rather than need for calories) often underlies excess caloric intake. As the reward centres that regulate drug and other forms of addiction are the same that are stimulated by highly palatable foods, it is not surprising that genes associated with substance and other addictions may also be linked with obesity.

This assumption finds new support in a study published this month in PLoS Genetics by Nancy Heard-Costa from Boston University School of Medicine on behalf of the CHARGE (Cohorts for Heart and Aging Research in Genome Epidemiology) consortium .

The researchers performed genetic analyses on more than 30,000 subjects participating in 8 large cohort studies, including the Age, Gene/Environment Susceptibility-Reykjavik Study (AGES- Reykjavik Study), the Atherosclerosis Risk in Communities Study (ARIC), the Cardiovascular Health Study (CHS), the European Special Population Network consortium (EUROSPAN), the Family Heart Study, the Framingham Heart Study, Old Order Amish (OOA), and the Rotterdam Study (RS).

Genetic loci studied included those identified in previous studies as well as new candidate loci for abdominal fat deposition.

In addition to confirming significant associations with the previously reported FTO and MC4R genes, the researchers found a novel locus in the NRXN3 gene associated with waist circumference, BMI and obesity.

NRNX3 has previously been associated with addiction (alcohol dependence, cocaine addiction, and illegal substance abuse) and is part of a family of central nervous adhesion molecules, which are highly expressed in sub-cortical regions of the brain in involved with learning and reward training.

Although the odds ratio for obesity per copy of the implicated G Allele was only 1.13, this small effect at a population level can be substantial.

More importantly, this finding clearly supports the notion that some individuals may be more susceptible to obesity because of an increased genetic predisposition to reward-seeking behaviours, that obviously include seeking out highly-palatable (addictive) foods.

Punitive approaches to drug addictions have not worked – neither will punitive approaches to obesity resulting from hedonic overeating.

AMS
Edmonton, Alberta

1 Comment

  1. I am enjoying reading your web page. This article reminded me of how little help there really is out there for people who struggle with weight. If I was adicted to drugs or alcohol I could actually turn myself in to a treatment centre and get help. With my obesity, I am told what to eat and go off and do it myself. Would they send the alcoholic to the bar and tell him to tough it out? I feel some days that I am driving myself insane at all the things that I am reading. I try to be “normal” but I still see my refection and feel my abilities diminish and it’s really hard to keep a positive outlook. I was referred to Med. Hat. Alta for WLS – it took 2 years, but I got my referral and sadly Jan of the year my referral was set for – I had a heart attack and after recovering and attending my appointment later that fall, I was told they don’t have the team to support me through surgery. The buck stopped there. I would think Manitoba Medical would have referred me on to a place that could handle me at that point (Edmonton) – but I guess I am supposed to resubmit and start the crap all over again. I didn’t need the stress of it – I felt it was a message from God telling me not to do it. But now I feel better and think I need to tackle this issue again. If I had the money, I would do it out of my own pocket – but I don’t and I don’t think it’s fair I should have to think that way. In the meantime – I read blogs like yours and hope that some day I will have the drive and determination to tackle it all over again. I am 49, 5’8″ and 320lbs. IHD, DMII – non smoker! Thank GOD I tackled that habit long ago!

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