Catechol-O-methyl transferase (COMT) (EC 2.1.1.6) is an enzyme first discovered by biochemist Julius Axelrod. COMT is the name given to the gene which codes for this enzyme.

Catechol-O-methyl transferase is involved in the breakdown of the catecholamine neurotransmitters, dopamine, epinephrine and norepinephrine. The enzyme introduces a methyl group to the catecholamine which is donated by S-adenosyl-methionine (SAM).

A functional polymorphism (a common normal variant) of the gene for catechol-O-methyl transferase has been shown to affect cognitive tasks broadly related to executive function, such as set shifting, response inhibition, abstract thought and the acquisition of rules or task structure.

The link between impairments in these sorts of cognitive tasks and the COMT gene is thought to be mediated by an effect on dopamine signalling in the frontal lobes.

Comparable effects on similar cognitive tasks, the frontal lobes and the neurotransmitter dopamine have also all been linked to schizophrenia. Unsurprisingly, an inherited variant of COMT is thought to be one of the genetic factors which may predispose someone to developing schizophrenia later in life.

See also

• dopamine
• schizophrenia