Related Experiment Video
Updated: Aug 29, 2026

The Attentional Set Shifting Task: A Measure of Cognitive Flexibility in Mice
Published on: February 4, 2015
Catechol O-methyltransferase Val158Met polymorphism in schizophrenia: differential effects of Val and Met alleles on
Karen A Nolan1, Robert M Bilder, Herbert M Lachman
1Nathan S. Kline Institute for Psychiatric Research, Orangeburg, NY 10962, USA.
Objective:
The catechol O-methyltransferase (COMT) Val158Met polymorphism has been associated with cognitive and behavioral phenotypes in schizophrenia. Whether COMT genotype is beneficial may depend on phenotype definition. The authors examined the effects of COMT genotype on a task that distinguishes imitation from reversal learning. They hypothesized that the Val and Met alleles would be associated with deficits in imitation learning and reversal learning, respectively.
Method:
Twenty-six patients with schizophrenia and schizoaffective disorder completed a task requiring alternation between imitation and reversal rules.
Results:
Met homozygotes showed better acquisition of the imitation rule but greater deficit shifting from imitation to reversal. Val homozygotes had poorer imitation performance and slower reaction times.
Conclusions:
The Met allele, by increasing tonic dopamine, may promote cognitive stability but limit cognitive flexibility.
Related Concept Videos
Pharmacogenetics of Drug Targets: β₂-Adrenergic Receptors, Apo E, Thymidylate Synthase
Drugs Affecting Neurotransmitter Synthesis
Pharmacogenetics of Drug Metabolism: Overview
Cognitive Enhancers: Cholinesterase Inhibitors and NMDA Receptor Antagonists
