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Smoking during pregnancy may increase child’s risk for schizophrenia

Prenatal exposure to nicotine was associated with increased risk for schizophrenia, according to recent findings.

“Nicotine readily crosses the placenta into the fetal bloodstream, with higher concentrations than in the pregnant woman. Nicotine specifically targets fetal brain development, causing short- and long-term changes in cognition, neuromorphology, and neurotransmitter function and altered regulation of neuronal apoptosis,” Solja Niemelä, MD, PhD, of the Research Unit of Clinical Neuroscience, University of Oulu, Finland, and colleagues wrote. “These effects occur in part through modulation of brain nicotinic acetylcholine receptors, which have a vital role in brain maturation. Moreover, prenatal nicotine exposure is related to epigenetic events, dysregulation of gene transcription in placental and fetal cells, and oxidative stress, which adversely influence brain development.”

To assess the relationship between prenatal nicotine exposure and schizophrenia, researchers analyzed cotinine level in archived maternal sera and schizophrenia prevalence in all live births in Finland from 1983 to 1998. Overall, 977 individuals with schizophrenia were identified and matched 1:1 to controls.

Higher maternal cotinine level was associated with increased risk for schizophrenia (OR = 3.41; 95% CI, 1.86-6.24; P < .0001).

Heavy maternal nicotine exposure, defined by researchers as cotinine levels greater than 50 ng/ml, was associated with a 38% increased risk for schizophrenia (OR = 1.38; 95% CI, 1.05-1.82; P = .02).

The findings were not accounted for by maternal age, maternal or parental psychiatric disorders, socioeconomic status and other covariates, according to researchers.

Researchers did not find clear evidence that weight or gestational age mediated associations.

“Prenatal nicotine exposure during gestation was related to an increased odds of schizophrenia. Given the high frequency of smoking during pregnancy, these results, if replicated, may ultimately have important public health implications for decreasing the incidence of schizophrenia,” the researchers wrote. “Further studies are necessary to address potential residual confounders.” – by Amanda Oldt

Disclosure: Niemelä reports receiving speakers’ bureau honoraria from Janssen, Lilly, and Lundbeck; receiving travel funds from Janssen and Lundbeck; and serving on advisory panels for Janssen and Lundbeck. Please see the full study for a list of all authors’ relevant financial disclosures.