Studies exploring the COMT gene and IQ in patients with schizophrenia
| Polymorphism | Study | Design | Country | Ancestry* | Participants, n | IQ measure | Mean IQ ± SD | Association between polymorphism and IQ in patients with SSD | ||
|---|---|---|---|---|---|---|---|---|---|---|
| Patients | Healthy controls | Patients | Healthy controls | |||||||
| rs4680† | Galderisi et al. (39) (2005) | Cross-sectional | Italy | Caucasian | 106 (schizophrenia) | NA | WAIS | NA | NA | No |
| rs4680 | Ho et al. (40) (2005) | Case–control | United States | Caucasian | 159 (schizophrenia) | 84 | WAIS§ | 91.0 ± 12.45 | 109.0 ± 12.05 | No |
| rs4680 | Prata et al. (41) (2009) | Case–control | United Kingdom | 90% Caucasian | 42 (schizophrenia) | 48 | WAIS, WASI§ | 97.2 ± 16.4 | 118.2 ± 11.5 | No |
| rs4680 | Wirgenes et al. (42) (2010) | Case–control | Norway | Caucasian | 171 (SSD) | 340 | WASI§ | 103.5 ± 13.8 | 113.6 ± 9.9 | No |
| rs4680 | Rebollo-Mesa et al. (43) (2011) | Case–control | United Kingdom | 84% Caucasian | 68 (SSD) | 208 | WAIS | NA | NA | Yes (only with antipsychotics) |
| rs4680 | Green et al. (44) (2014) | Case–control | Australia | Caucasian | 617 (SSD) | 659 | WTAR§ | 97.49 ± 15.04 | 105.47 ± 10.67 | Yes |
| rs4680, rs1801133‡ | Kontis et al. (45) (2013) | Case–control | Greece | NA | 90 (schizophrenia) | 55 | WAIS | 81.06 ± 11.35 | NA | Yes |
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.