Low Maternal Thyroid Hormone During Pregnancy Increases Schizophrenia Risk in Offspring

PHILADELPHIA -- June 22, 2016 -- A study published in Biological Psychiatry reveals a new link between low levels of the thyroid hormone thyroxine during pregnancy and risk of schizophrenia in the offspring.

Low levels of free thyroxine in pregnant women are associated with abnormalities in cognitive development similar to those in schizophrenia. Hypothyroxinaemia is also associated with preterm birth, a risk factor for schizophrenia.

To determine if hypothyroxinaemia is associated with schizophrenia, Alan Brown, MD, Columbia University Medical Center, and the New York State Psychiatric Institute, New York, New York, and colleagues examined thyroxine levels in archived serum samples from 1,010 mothers of children with schizophrenia and 1,010 matched control mothers.

The sera were collected during the first and early second trimesters of pregnancy as part of the Finnish Maternity Cohort. Comprehensive Finnish registries of the population and psychiatric diagnoses provided information on case status (schizophrenia or control) among offspring of mothers corresponding to the prenatal serum samples.

The authors found that 11.8% of people with schizophrenia had a mother with hypothyroxinaemia, compared with 8.6% of people without schizophrenia. This suggests that children of mothers with hypothyroxinaemia during pregnancy have increased odds of developing schizophrenia. The association remained even after adjusting for variables strongly related to schizophrenia such as maternal psychiatric history and smoking.

“This work adds to a body of literature suggesting that maternal influences, both environmental and genetic, contribute to the risk of schizophrenia,” said David Gyllenberg, MD, University of Turku, Turku, Finland. “Although replication in independent studies is required before firm conclusions can be drawn, the study was based on a national birth cohort with a large sample size, increasing the plausibility of the findings.”

This study did not address the cause of this association, but did find that adjusting for preterm birth lessened the association between hypothyroxinaemia and schizophrenia, suggesting that preterm birth may mediate some of the increased risk.

The authors noted in the paper that the finding may not be specific to schizophrenia, and should be studied as a risk factor for other neurodevelopmental disorders as well, such as bipolar disorder and autism.

SOURCE: Elsevier
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