Age modulates the effect of COMT genotype on delay discounting behavior.

ABSTRACT: A form of impulsivity, the tendency to choose immediate over delayed rewards (delay-discounting) has been associated with a single nucleotide polymorphism (SNP) in the catechol-O-methyltransferase (COMT) gene (COMTval¹??met; rs4680). However, the existing data regarding the nature of this association are in conflict. We have previously reported that adults homozygous for valine (val) at the COMTval¹??met SNP demonstrate greater delay-discounting than do methionine (met) allele carriers (Boettiger et al., J Neurosci 27:14383-14391, 2007). In contrast, a recent study of adolescent males found that those with the met/met genotype demonstrate greater delay-discounting than do val-allele carriers (Paloyelis et al., Neuropsychopharmacology 35:2414-2426, 2010). Based on reported age-related changes in frontal dopamine function and COMT expression, we hypothesized that the association of COMT genotype with delay-discounting behavior is modulated by age from late adolescence to young adulthood.To test this hypothesis, we genotyped late adolescents (18-21 years; n?=?72) and adults (22-40 years; n?=?70) for the COMTval¹??met polymorphism, measured their delay-discounting behavior, and tested for an interaction between age group and COMT genotype.This cross-sectional study found that age modulates COMTval¹??met genotype effects on delay-discounting behavior. Among met-carriers, delay-discounting was negatively correlated with age from late adolescence to adulthood, while among val/val individuals delay-discounting was positively correlated with age across this range.These results confirm our previous finding of enhanced delay-discounting among val/val adults relative to met-allele carriers, and help reconcile existing literature. We propose a single U-shaped model of the relationship between frontal DA levels and impulsive choice that accounts for both adolescent and adult data.

SUBMITTER: Smith CT 

PROVIDER: S-EPMC3401276 | biostudies-literature | 2012 Aug

REPOSITORIES: biostudies-literature