A new study from Denmark suggests that there may be a link. Published in the November issue of the British Journal of Psychiatry, the study set out to discover whether prenatal exposure to analgesics may affect the development of the nervous system of the foetus, leading to an increased risk of schizophrenia in adulthood. Results show that mothers who take analgesics in the second three months of pregnancy are four times more likely to have a child that will develop schizophrenia.
What the research brings particular attention to are the precise periods of high risk during pregnancy. Findings show that when exposed to analgesics in the first trimester of pregnancy, the risk of schizophrenia for infants was only significant for the third month, and was not significant for the third trimester. However, the incidence of schizophrenia in both males and females exposed to analgesics during the second trimester was more than four times higher than in the non-exposure group during that period.
Why the increased risk during this period? The authors of the study explain that it is during the second trimester that the cortical subplate of the brain reaches its peak of development. This may be a period when the immature foetal brain is particularly sensitive to a range of environmental influences, and specifically, to the effects of analgesics.
The research also found that association was slightly stronger in females than males. This association was independent of maternal schizophrenia, which was the strongest risk factor for schizophrenia in this study. Other known risk factors, such as parental history of schizophrenia, second-trimester viral infections, treatment with other drugs, pregnancy complications, parental social status and parental age were all taken into account. The link between prenatal exposure to analgesics and schizophrenia was found to be independent of all these risk factors.
The study took into account a total of 7999 infants, with a total of 116 cases of schizophrenia identified. However, authors of the study have cautioned that as only 6.9 per cent of all those with schizophrenia had been exposed to analgesics in the second trimester, the research needs to be replicated before prenatal exposure to analgesics can be added to the list of demonstrated risk factors for schizophrenia.
To view an abstract of the British Journal of Psychiatry article, follow this link.