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Twins with schizophrenia: genes or germs?
1Dept. of Psychology, Southwest Missouri State University, Springfield 65804-0027, USA.
Schizophrenia Bulletin
|January 1, 1995
Summary
Genetics aren't the only factor in schizophrenia. Shared prenatal environments, like viral infections in monochorionic twins, significantly influence schizophrenia concordance rates in identical twins.
Area of Science:
- Psychiatry
- Genetics
- Developmental Psychology
Background:
- High concordance rates for schizophrenia in monozygotic (identical) twins suggest a strong genetic component.
- However, shared prenatal environments, including potential viral infections, can also influence these rates, even in twins separated at birth.
Purpose of the Study:
- To investigate the role of prenatal environment, specifically viral infections, in schizophrenia concordance among monozygotic twins.
- To use placentation status as a proxy for shared prenatal environment and infection risk.
Main Methods:
- Reviewed published twin studies focusing on schizophrenia concordance and handedness.
- Utilized handedness concordance as a retrospective marker for placentation status (monochorionic vs. dichorionic).
- Compared psychosis concordance rates between monozygotic twin pairs with same-hand vs. opposite-hand preferences.
Main Results:
- Monozygotic twin pairs with opposite-hand preferences showed a 60% concordance for psychosis (9/15 pairs).
- Monozygotic twin pairs with same-hand preferences showed a 32% concordance for psychosis (18/56 pairs).
Conclusions:
- Results suggest that shared prenatal viral infections may contribute significantly to the high concordance rates observed for schizophrenia in identical twins.
- Placentation status, inferred from handedness, is a potential indicator of shared prenatal factors influencing schizophrenia risk.