Table 1

Studies exploring the COMT gene and IQ in patients with schizophrenia

PolymorphismStudyDesignCountryAncestry*Participants, nIQ measureMean IQ ± SDAssociation between polymorphism and IQ in patients with SSD
PatientsHealthy controlsPatientsHealthy controls
rs4680Galderisi et al.39 (2005)Cross-sectionalItalyCaucasian106 (schizophrenia)NAWAISNANANo
rs4680Ho et al.40 (2005)Case–controlUnited StatesCaucasian159 (schizophrenia)84WAIS§91.0 ± 12.45109.0 ± 12.05No
rs4680Prata et al.41 (2009)Case–controlUnited Kingdom90% Caucasian42 (schizophrenia)48WAIS, WASI§97.2 ± 16.4118.2 ± 11.5No
rs4680Wirgenes et al.42 (2010)Case–controlNorwayCaucasian171 (SSD)340WASI§103.5 ± 13.8113.6 ± 9.9No
rs4680Rebollo-Mesa et al.43 (2011)Case–controlUnited Kingdom84% Caucasian68 (SSD)208WAISNANAYes (only with antipsychotics)
rs4680Green et al.44 (2014)Case–controlAustraliaCaucasian617 (SSD)659WTAR§97.49 ± 15.04105.47 ± 10.67Yes
rs4680, rs1801133Kontis et al.45 (2013)Case–controlGreeceNA90 (schizophrenia)55WAIS81.06 ± 11.35NAYes
  • NA = not available; SD = standard deviation; SSD = schizophrenia spectrum disorder; WAIS = Wechsler Adult Intelligence Scale; WASI = Wechsler Abbreviated Scale of Intelligence; WTAR = Wechsler Test of Adult Reading.

  • * Terminology taken from the original articles.

  • rs4680 is commonly known as the Val158Met polymorphism.

  • rs1801133 is located in the MTHFR gene.

  • § Patients had significantly lower IQs than healthy controls.