A STUDY OF THE DOPAMINE D-2 RECEPTOR GENE IN PATHOLOGICAL GAMBLING

Pathological gambling has been termed both the 'pure' and the 'hidden' addiction, 'Pure' because it is not associated with the intake of any addicting substance, and 'hidden' because it is an extension of a com mon, socially accepted behaviour. The Taq A1 variant of the human DRD2 gene has been associated with drug addiction, some forms of severe al coholism, and other impulsive, addictive behaviours, We have sought to determine if there is a similar association with pathological gamblin g, A total of 222 non-Hispanic Caucasian pathological gamblers from mu ltiple sites across the US participated in the study, Of these 171 don ated a sample of blood, 127 filled out several questionnaires, and 102 did both, Of the 171 pathological gamblers 50.9% carried the D(2)A1 a llele versus 25.9% of the 714 known non-Hispanic Caucasian controls sc reened to exclude drug and alcohol abuse, p < 0.00000001, odds ratio ( OR) = 2.96. For the 102 gamblers who filled out the questionnaires, 63 .8% of those in the upper half of the Pathological Gambling Score (mor e. severe) carried the D(2)A1 allele (OR versus controls = 5.03), comp ared to 40.9% in the lower half (less severe), Of those who had no com orbid substance abuse, 44.1% carried the D(2)A1 allele, compared to 60 .5% of those who had comorbid substance abuse. Forty-eight controls an d 102 gamblers completed a shorter version of the Pathological Gamblin g Score. Of the 45 controls with a score of zero, 17.8% carried the D( 2)A1 allele. Of the 99 gamblers with a score of 5 or more, 52. 5% carr ied the D(2)A1 allele (chi(2) = 15.36, P = 0.00009), These results sug gest that genetic variants at the DRD2 gene play a role in pathologica l gambling, and support the concept that variants of this gene are a r isk: factor for impulsive and addictive behaviours.