December 2, 2015. The previously reported link between a mother’s infection during pregnancy and risk for psychosis in her children may not be so straightforward, according to a study of nearly two million people published online August 24 in Schizophrenia Bulletin. Led by Asa Blomstrom and Christina Dalman at the Karolinska Institute in Stockholm, Sweden, the study did not find an association between maternal infection and non-affective psychoses such as schizophrenia in offspring. They did find a link, however, when looking among mothers with a psychiatric illness themselves. This suggests that a “double hit” of a mother’s vulnerability and infection work together to increase risk.
“The most interesting finding is this evidence of a synergistic effect between infection and the mother’s history of psychiatric illness,” said Alan Brown of Columbia University in New York City, who was not involved in the study and who noted that this history may reflect genetic as well as environmental risk factors.