The finding, based on a large population-based case control study of all live births in Finland over a 15-year period, suggests that efforts to decrease smoking during pregnancy may help decrease the incidence of schizophrenia.
A team of researchers from several institutions in Finland and New York prospectively analyzed cotinine levels in serum obtained during the pregnancies of women in Finland from 1983 to 1998. Cases of schizophrenia in offspring (N=977) were identified from a national registry and matched 1:1 to control subjects based on date of birth, sex, and residence.
The researchers found that a higher maternal cotinine level was associated with increased odds of schizophrenia in offspring; heavy maternal nicotine exposure (defined as cotinine level greater than 50 ng/ml) was associated with a 38% increased odds of schizophrenia. The association persisted after adjusting for maternal age, maternal or parental psychiatric disorders, and socioeconomic status, and the authors noted that there was no clear evidence of mediation of this relationship by low weight for gestational age.
“To our knowledge, this is the first biomarker-based study to show a relationship between fetal nicotine exposure and schizophrenia,” the authors wrote. “The plausibility of these findings is supported by an extensive literature on prenatal smoking and neurocognition. Offspring of mothers who smoke have delayed psychomotor and mental developmental scores; deficits in sustained attention, verbal learning, and design memory; impaired speech and language; and lower IQ. Low premorbid IQ and other neurocognitive abilities have been related to schizophrenia.”
The authors concluded, “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.”
(Image: iStock/Baris Muratoglu)