COMT and schizophrenia: The dopamine hypothesis of schizophrenia, which has greatly influenced research into the mechanisms underlying the onset of psychosis, suggests that COMT is an attractive candidate gene underlying susceptibility to schizophrenia [159,160,161,162], and studies of Comt−/− mice have demonstrated the ability of the COMT enzyme to control the extra-cellular clearance of PFC dopamine and influence cognitive functions such as working memory [6,163,164].