Toxoplasma gondii and Other Risk Factors for Schizophrenia: An Update Full Text
Schizophrenia Bulletin, 03/29/2012  Clinical Article

Torrey EF et al. – Low–risk factors include a history of traumatic brain injury, sex abuse in childhood, obstetrical complications, having a father 45 or older, specific genetic polymorphisms, birth seasonality, maternal exposure to influenza, or prenatal stress.

• The failure to find genes of major effect in schizophrenia has refocused attention on nongenetic, including infectious factors.
• In a previous study, antibodies to Toxoplasma gondii were found to be elevated in 23 studies of schizophrenia (OR 2.73; 95% CI 2.10-3.60).
• The current study replicates this finding with 15 additional studies (OR 2.71; 95% CI 1.93-3.80) and compares this with other identified schizophrenia risk factors.
• The highest risk factors are having an affected mother (relative risks [RR] 9.31; 95% CI 7.24-11.96), father (RR 7.20; 95% CI 5.10-10.16), or sibling (RR 6.99; 95% CI 5.38-9.08) or being the offspring of immigrants from selected countries (RR 4.5; 95% CI 1.5–13.1).
• Intermediate risk factors, in addition to infection with T. gondii, include being an immigrant from and to selected countries (RR 2.7; 95% CI 2.3-3.2), being born in (RR 2.24; 95% CI 1.92-2.61) or raised in (RR 2.75; 95% CI 2.31-3.28) an urban area, cannabis use (OR 2.10-2.93; 95% CI 1.08-6.13), having minor physical anomalies (OR 2.23; 95% CI 1.42-3.58), or having a father 55 or older (OR 2.21-5.92; 95% CI 1.46-17.02).