Genetic Variation of the MAO B Gene is Related to Shorter Reaction Times in Alcohol Dependent Patients - Abstract
Introduction: Both low levels of platelet monoamine oxidase B (MAO B) and polymorphisms of the MAO A gene coding for MAO A activity have been found to be associated with alcoholism and violent or impulsive aggression, while associations of these variables with the polymorphism of the MAO B gene coding for MAO B activity have hardly been reported. Therefore the present study tries to investigate if the polymorphism rs1799836 of the MAO B gene located on intron 13 of chromosome X is associated with alcohol dependence, and if possible associations between aggression related personality traits and the MAO B polymorphism are different in patients and controls.
Method: In a small pilot study including 60 male alcohol dependent patients and individually matched healthy controls, personality questionnaire scores on aggression and impulsivity and reaction times in a Go/NoGo task as a measure of impulsive behavior were obtained and genotypes A and G for the single nucleotide polymorphism on the MAO B gene (rs1799836) were determined.
Results: The ratios of A and G carriers in patients and controls were both equivalent to ratios in Caucasian populations and not statistically different between groups. Aggression and impulsivity scores were not statistically different between genotypes, but significantly faster reaction times were observed in G-as compared to A-genotype participants exclusively in the patient group (p=.016).
Discussion: Although no association between the polymorphism of the MAO B gene and alcohol
dependence was observed, and the association with aggression failed to reach statistical significance, it is noteworthy that faster reaction times in carriers of the G allele were exclusively observed in alcohol dependent patients and not in controls This might be explained by the possible effects of the investigated polymorphism on brain dopamine levels modified by alcohol dependence.
Conclusions: The study provides a hypothesis for a novel functional significance of the MAO B
gene associated with alcohol dependence.