COMT Val158Met polymorphism, cognitive stability and cognitive flexibility: an experimental examination.
BACKGROUND
Dopamine in prefrontal cortex (PFC) modulates core cognitive processes, notably working memory and executive control. Dopamine regulating genes and polymorphisms affecting PFC--including Catechol-O-Methyltransferase (COMT) Val158Met--are crucial to understanding the molecular genetics of cognitive function and dysfunction. A mechanistic account of the COMT Val158Met effect associates the Met allele with increased tonic dopamine transmission underlying maintenance of relevant information, and the Val allele with increased phasic dopamine transmission underlying the flexibility of updating new information. Thus, consistent with some earlier work, we predicted that Val carriers would display poorer performance when the maintenance component was taxed, while Met carriers would be less efficient when rapid updating was required.


METHODS
Using a Stroop task that manipulated level of required cognitive stability and flexibility, we examined reaction time performance of patients with schizophrenia (n = 67) and healthy controls (n = 186) genotyped for the Val/Met variation.


RESULTS
In both groups we found a Met advantage for tasks requiring cognitive stability, but no COMT effect when a moderate level of cognitive flexibility was required, or when a conflict cost measure was calculated.


CONCLUSIONS
Our results do not support a simple stability/flexibility model of dopamine COMT Val/Met effects and suggest a somewhat different conceptualization and experimental operationalization of these cognitive components.
Rosa
Elise C
EC
Clinical Brain Disorders Branch, National Institute of Mental Heath/National Institutes of Health, 10 Center Drive, MSC 1379, Bethesda, MD 20892, USA.
Dickinson
Dwight
D
Apud
José
J
Weinberger
Daniel R
DR
Elvevåg
Brita
B
D000328:Adult; D000483:Alleles; D002394:Catechol O-Methyltransferase / Q000235:genetics*; D003071:Cognition; D005260:Female; D006801:Humans; D008297:Male; D011110:Polymorphism, Genetic; D011930:Reaction Time / Q000235:genetics*; D012559:Schizophrenia / Q000235:genetics*; D012565:Schizophrenic Psychology
D002394:Catechol O-Methyltransferase