March 27, 2007

Birth Order's Effect on Schizophrenia Severity Studied

Researchers studied families in which siblings had schizophrenia or schizoaffective disorder. They found that the younger sibling, i.e. the one born later, was more likely to have a more severe form of schizophrenia than the older sibling.

According to Psychiatry Source, the siblings seemed to function socially and occupationally (at work) at about the same levels before becoming ill. However, the younger sibling was more likely to have the onset of schizophrenia at an earlier age (1.5 years earlier). Also, although birth order did not affect the severity of the worst episode, the later born sibling was less likely to regain the same level of functioning (socially, occupationally, and emotionally) as before the illness began.

The researchers reported in the journal Psychiatry Research that their findings gave some support to the theory that schizophrenia may be affected by the birth order effects of the maternal immune response to the fetus, but that many other factors linked to birth order which were not measured may have influenced the results seen. These factors include increasing parental age, decreasing parental health, increased maternal stress in later pregnancies, and differing social environments for later-born children.

The researchers say that more research is needed to explore the possibility that maternal antibodies to genetically determined factors in the developing fetus (maternal-fetal genotype incompatibility) is a risk factor in the development of schizophrenia.

Thanks goes to Tim^ for letting us know about this information.

Read the full article: Birth order affects schizophrenia severity
Original Source Abstract: Birth order and the severity of illness in schizophrenia

Related Reading:
Psychosis Among Siblings of Schizophrenia Patients
Family-based clusters of cognitive test performance in familial schizophrenia


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