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Shorter period of parental sexual contact may increase offspring risk for schizophrenia

Offspring born to couples in sexual contact for less than 3 years before conceiving them may be at a slightly increased risk for schizophrenia, study findings showed.

Prior evidence has shown that short duration of marriage is a risk factor for preeclampsia, which is also associated with risk for schizophrenia, according to the researchers.

“Maternal intolerance to the fetal (paternal) antigens is a risk factor for preeclampsia,” Dolores Malaspina, MD, MPH, from the department of psychiatry, Icahn School of Medicine at Mt Sinai, and colleagues wrote in Schizophrenia Research. “A lengthy period of pre-pregnancy vaginal exposure to the sperm of the offspring's father can overcome maternal intolerance, although other maternal inflammatory conditions are also risk factors for preeclampsia. If maternal immune intolerance is a component pathway of the risk for schizophrenia then the couples' duration of pre-pregnancy sexual contact could be related to the offspring risk for schizophrenia.”

Researchers examined offspring risk for schizophrenia and separated this risk from the interrelated measures of parental age, father’s age at marriage, parental psychiatric diagnoses and duration of marriage using data from more than 90,000 offspring in a Jerusalem birth cohort study (1964 to 1976). They cross-linked psychiatric diagnoses in offspring and parents using Israel's psychiatric case registry and obtained duration of marriage and paternal age at marriage information from birth certificates.

The investigators reported that the risk for schizophrenia declined for each 5 years parents were married (RR = 0.83; 95% CI, 0.75-0.95). Stratified analyses showed that offspring had the greatest risk for schizophrenia when they were born to couples married for less than 2 years (RR = 1.53; 95% CI, 1.11-1.66), with reduced risk for those with 2 to 4 years of marriage (RR = 1.38; 95% CI, 1.05-1.81) compared with those married for longer than 10 years.

The findings that children of parents with shorter durations of marriage being at higher risk for schizophrenia was independent of the risk related to parental psychiatric diagnoses and paternal age. Accounting for duration of marriage and later parental age eliminated the observed risk tied to later fathers' age at marriage (RR = 1.27; P < .0001), according to the study.

“The risk from a short period of parental sexual cohabitation may be a modifiable risk factor for offspring schizophrenia risk,” Malaspina and colleagues wrote. “The results highlight a novel significant risk factor for fathers related to their duration of sexual contact with the mother prior to conception, which is associated with preeclampsia, proposed to be the linking mechanism. This common condition could underlie the immune activation that is proposed to underlie a central pathology for the disease.” – by Savannah Demko

Disclosure: The authors report no relevant financial disclosures.