MedWire News: The socioeconomic status (SES) of family origin is significantly associated with schizophrenia subtype, whereas a family history of mental illness is not, US scientists have discovered.

Many studies have reinforced the genetic model of schizophrenia. However, there have been few investigations of the relationship between a family history of serious mental illness and deficit versus nondeficit schizophrenia, explain Brian Jones, from Villanova University in Pennsylvania, and colleagues.

The teamtherefore administered the Scale for the Assessment of Positive Symptoms, the Scale for the Assessment of Negative Symptoms, the Positive and Negative Symptom Scale, and the Social Service Assessment to 437 schizophrenia inpatients.

In addition, the researchers examined hospital records to classify patients in terms of their SES of family origin (poor versus nonpoor). They also divided the patients into deficit and nondeficit presentation and those with a family history within the immediate family, within the extended family, or no evidence of mental illness history.

Multivariate logistic regression analysis demonstrated that SES of family origin had a statistically significant association with deficit versus nondeficit schizophrenia, at an odds ratio of 0.644. However, family history, race, and gender were not associated with schizophrenia subtype.

Further analysis of contingency tables and variance revealed that poverty was associated with deficit schizophrenia independently of family history, while family history had no net association with the type of schizophrenia.

"Overall, our findings support the hypothesis that, while risk of schizophrenia in general is genetically based, the specific form of the psychosis stems from environmental stressors including fetal brain insults such as in utero infection," the team concludes.

The research is published in the journal Psychiatry Research.

Free abstract