Plasma homovanillic acid: A significant association with alcoholism is independent of a functional polymorphism ofthe human catechol-o-methyltransferase gene

The central dopamine system seems to influence addictive disorders. Plasma homovanillic acid (HVA) is an indicator of central dopaminergic activity. In this study the hypothesis that plasma HVA is associated with alcoholism or with delirium tremens (DT) duringalcohol withdrawal was tested. A functional genetic polymorphism of the enzyme catechol-O-methyl transferase (COMT) thatparticipates in converting dopamine into its finalmetabolite HVA was investigated for an association with alcoholism or DT duringalcohol withdrawal. In addition, a relation between the functional polymorphism of COMT and plasma HVA concentrations was studied.Plasma HVA concentrations and COMT genotypes were determined in 142 German alcoholics and 101 German healthy controls.Alcoholic patients were examined after a minimum of 3 weeks after cessation of drinking. Mean plasma HVA concentrations weresignificantly lower in alcoholic patients compared to healthy controls. A group of alcoholics with a history of DT during alcoholwithdrawal(n = 62) did not differ significantly in plasma HVA concentrations from alcoholics with a history of only mild withdrawalsymptoms (n = 67). The functional polymorphism of the human COMT gene was neither significantly associated with the diagnosis ofalcoholism or DT during alcohol withdrawal nor with plasma HVA concentrations.