Parental psychosis affects early schizophrenia risk factors

By Liam Davenport, medwireNews Reporter

Parental psychosis alters the impact that individual biological risk factors during pregnancy and birth have on future schizophrenia risk, say Finnish researchers.

Emmi Keskinen (University of Oulu) and colleagues found that biological factors such as high birth weight and length and high maternal age only increased the risk for schizophrenia in individuals born to parents with psychosis.

They suggest in Schizophrenia Research that "in clinical practice and the early screening of individuals with high risk of developing schizophrenia, targeting interventions towards those with parental psychosis could be effective."

Studying 10,526 people enrolled in the Northern Finland 1966 Birth Cohort, the team identified 150 (1.4%) individuals who developed schizophrenia by 44 years of age. Of this group, 18 (12.0%) had parents with psychosis, compared with 495 (4.8%) individuals without schizophrenia, indicating that parental psychosis increased schizophrenia risk 2.8-fold.

In the parental psychosis group, the risk for schizophrenia was increased by high birth weight and length (hazard ratios [HRs]=11.4 and 4.1), high birth weight in relation to gestational age (HR=3.2), high maternal age (HR=2.6), and maternal depressed mood during pregnancy (HR=2.7).

By contrast, the factors increasing the risk for schizophrenia among individuals without parental psychosis were low birth weight and length (HR=2.2 and 2.4) and maternal high level of education (HR=1.5).

"Any biological risk factor" significantly increased schizophrenia risk only among individuals with parental psychosis, at a hazard ratio of 4.0, the researchers note.

Also, while the interaction between biological risk for schizophrenia and parental psychosis was significant, it was nonsignificant for psychosocial risk and parental psychosis.

The investigators call for further investigation into the mechanisms underlying the risk factors that takes into account parental psychosis.

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