alcoholism allele

over at world of psychology i posted about a study revealing the possible genetic link to alcoholism and enjoyment of alcohol.

alcohol promotes release of endogenous opioids, which activate mu opioid receptors in the brain. this opioid system in turn affects the mesolimbic dopamine system involved in craving, reinforcement, and motivation. the mu opioid receptors are encoded by a specific gene, oprm 1, and they come in two varieties: the g and a version.

Results indicate that individuals with the G allele had higher subjective feelings of intoxication, stimulation, sedation, and happiness across trials as compared to participants with the A allele.

which sounds great for those with the g allele. but there's a major drawback to this higher level of enjoyment - it creates more stimulation of those dopamine receptors involved in reinforcement and motivation, leading to higher probability of addiction. it seems to follow that this pattern may be the same for other drugs that stimulate the opioid system such as heroin, opium, and cocaine (cocaine indirectly, because as with alcohol it is not an opiate derivative).

this is an incredible finding with heath and policy implications. it is important to be aware of a genetic predisposition for any disorder, so one may modify his/her behavior. just one may watch his/her eating and exercise habits if predisposed to diabetes or heart disease, one with a g allele should be careful of alcohol consumption.

as g allele folks get "higher subjective feelings of intoxication, stimulation, sedation" and etc. with lower blood alcohol levels than the a types. should a and g allele folks be subject to the same blood alcohol levels in drunk-driving tests, then? (actually, a different test would be better still)

in addition, i wonder if those with a alleles are subject to comparatively heavier binge drinking and therefore health problems than one with a g allele (for those who do not develop chronic alcoholism). since a types must drink more to become intoxicated, and to many the goal of drinking is intoxication, it seems logical that they would drink more on a particular night. just imagine if you needed 1,000 more calories per day to feel full than someone else the same size. you'd definitely feel the physical effects of that.

reference: Hutchison, K. E. and Ray, L. A. "A polymorphism of the gamma-opioid receptor gene (OPRM1) and sensitivity to the effects of alcohol in humans." Alcoholism: Clinical & Experimental Research, 28, 12

Labels: neuroscience, well being