Prenatal viral exposure is described as a risk factor that increases the odds of developing schizophrenia when combined with what?

• A. Pre-existing genetic risks
• B. Substance use
• C. Urban upbringing
• D. Early childhood trauma

Answer: (A)

This is about gene-environment interaction in schizophrenia. Prenatal viral exposure acts as an environmental insult to fetal brain development, but the impact is much greater when there is pre-existing genetic vulnerability. In other words, individuals with a genetic risk for schizophrenia have a higher chance of developing the disorder if they were exposed to a viral infection in utero, compared with those without that genetic risk. The prenatal infection and the genetic predisposition combine to raise odds beyond what either factor would produce alone, illustrating how biology and environment work together in the onset of schizophrenia.

Other factors like substance use, urban upbringing, or early childhood trauma are themselves risk factors, but the scenario described emphasizes the specific interaction between an in utero environmental exposure and inherent genetic risk.