Neonatal antibodies to infectious agents and risk of bipolar disorder: a population-based case-control study.

Mortensen, Preben Bo; Pedersen, Carsten Bøcker; McGrath, John Joseph; Hougaard, David Michael; Nørgaard-Petersen, Bent; Mors, Ole; Børglum, Anders D; Yolken, Robert H

OBJECTIVE There is a substantial evidence base linking prenatal exposure to infectious agents and an increased risk of schizophrenia. However, there has been less research examining the potential for these exposures to also contribute to risk for bipolar disorder. The aim of this study was to examine the association between neonatal markers of selected prenatal infections and risk for bipolar disorder. METHODS Using population-based Danish registers, we examined 127 individuals with a diagnosis of bipolar disorder, and 127 sex and day-of-birth individually matched controls. Based on neonatal dried blood spots, we measured antibodies to herpes simplex virus type 1 (HSV-1) and 2 (HSV-2), cytomegalovirus (CMV), and Toxoplasma gondii. Relative risks were calculated for the matched pairs when examined for optical density units for antibodies to each of the infectious agents. RESULTS There was no association between any of the neonatal markers of prenatal infection and risk of bipolar disorder. CONCLUSIONS In contrast with studies of schizophrenia, our analysis does not support maternal infection with HSV-1, HSV-2, CMV, or Toxoplasma gondii as risk factors for bipolar disorder. However, larger study samples are needed, and data on, for example, specific serotypes of Toxoplasma and indicators of the timing of maternal infection are still warranted.