According to the US Surgeon General, genetic factors are thought to account for 40 to 70 percent of individual differences in risk for addiction. Although multiple genes are likely involved, only a few specific gene variants have been identified that either predispose to or protect against addiction.
I was curious to find out what some of these gene variants are, so I started looking.
The D2 Dopamine Receptor Gene: A Review of Association Studies in Alcoholism and Phenotypes
The role of the D2 dopamine receptor gene in alcoholism has come under intense investigation since the A1 allele of the gene was first reported to be associated with alcoholism.
Allele – an alternative or variant form of a gene
In a review of 14 American and international studies, alcoholics had a higher occurrence of of the A1 allele than controls. Severe alcoholics had a threefold higher prevalence of the A1 allele than non-alcoholics. The A1 allele has also been associated with other drug problems including cocaine and nicotine.
The study consisted of 1,015 alcoholics and 898 controls. Since there were multiple studies analyzed, controls included people assessed as non-alcoholics and those who had been randomly selected and not assessed for alcoholism.
Noble concluded that among Caucasian studies, the association of the DRD2 A1 allele was stronger when more severe alcoholics are compared with assessed non-alcoholics. Evidence across studies suggested that it’s differences in the expression of D2 dopamine receptors, not structure, that contribute to the development of substance abuse disorders.
I found this study to be interesting because it observed a significant genetic difference between alcoholics and non-alcoholic subjects. I’m motivated to better understand this type of research as it relates to improving diagnosis, screening, and treatment.
Let me know if you liked this type of post and want to see more!
Noble, Ernest P. 1998. “The D2 Dopamine Receptor Gene.” Alcohol 16 (1): 33-45. doi:10.1016/S0741-8329(97)00175-4. http://resolver.scholarsportal.info/resolve/07418329/v16i0001/33_tddrg.