Association between the catechol-O-methyltransferase (COMT) ValMet polymorphism and motor behavior in healthy adults: A study review.

The influence of individual differences in cognition and behavior may be partly explained by the different genetic polymorphisms. Among the genetic polymorphisms capable of altering cognitive and behavioral functions, the catechol-O-methyltransferase (COMT) Val158Met polymorphism regulates the availability of dopamine (DA) in the prefrontal cortex and has a trimodal distribution in the population. The Met allele has higher DA availability in the synaptic clefts and can be associated with cognitive stability. Val homozygous individuals exhibit lower DA concentrations in the synaptic clefts, which can be associated with cognitive flexibility. Heterozygotes have intermediate DA concentrations in the synaptic clefts. In the perspective of motor behavior, greater cognitive stability would be advantageous when the practice requires maintenance and refinement of a movement pattern, while a greater cognitive flexibility would be fundamental for practices demanding motor adaptation caused by disturbances. Thus, this integrative review aimed to analyze, in healthy populations, possible associations between the COMT polymorphism and motor behavior, as well as to investigate whether the effects of the COMT genotypes from the perspective of the roles played by tonic and phasic DA are associated with the stability/flexibility required by the nature of the motor task. The search for the articles was carried out in the PubMed, ISI Web of Science and Scopus databases. Six studies that met all the requirements specified in the inclusion criteria were selected. Results suggest an association between COMT polymorphism and motor behavior. Conflicting results regarding the effects of the different COMT polymorphisms on adaptation and sequential motor tasks were found, as well as on the roles played by tonic and phasic DA. Despite the inconsistencies encountered, it was possible to identify that the different COMT genotypes lead to different effects in relation to the nature of the practiced motor task. Due to the reduced number of articles investigating the association between COMT polymorphism and motor behavior, relevant questions about this relation remain under-investigated.