Table 2

Studies exploring the BDNF gene and IQ in patients with schizophrenia

PolymorphismStudyDesignCountryAncestry*Participants, nIQ measureMean IQ ± SDAssociation between polymorphism and IQ in patients with SSD
PatientsHealthy controlsPatientsHealthy controls
rs6265Ho et al.46 (2006)Case–controlUnited StatesNA293 (SSD)144WAIS91.49 ± 13.49110.41 ± 11.66No
rs6265Chung et al.47 (2010)Case–controlSouth KoreaEast Asian101 (schizophrenia)50WAIS102.45 ± 14.1107.9 ± 10.4Yes (only before statistical correction)
rs6265Lu et al.48 (2012)Case–controlChinaEast Asian112 (SSD)63WAIS87.8 ± 14.7113.4 ± 14.2Yes
rs6265Smith et al.49 (2012)Case–controlCanada72% Caucasian, 10% South Asian, 9% East Asian, 9% Other58 (first episode of psychosis)39NAART100.4 ± 8.7NANo
rs6265Abbasian et al.50 (2021)Case–controlIranAsian71 (schizophrenia)88WAIS85.48 ± 13.698.30 ± 15.12No
  • NA = not available; NAART = North American Adult Reading Test; SD = standard deviation; SSD = schizophrenia spectrum disorder; WAIS = Wechsler Adult Intelligence Scale.

  • * Terminology taken from the original articles.

  • rs6265 is commonly known as the Val66Met polymorphism.

  • Patients had significantly lower IQs than healthy controls.