Serological Documentation of Maternal Influenza Exposure and Bipolar Disorder in Adult Offspring

Objective
The authors examined whether serologically confirmed maternal
exposure to influenza was associated with an increased risk of bipolar
disorder in the offspring and with subtypes of bipolar disorder, with
and without psychotic features.

Method
The study used a nested case-control design in the Child Health
and Development Study birth cohort. In all, 85 individuals with bipolar
disorder were identified following extensive ascertainment and
diagnostic assessment and matched to 170 comparison subjects in the
analysis. Serological documentation of maternal exposure to influenza
was determined using the hemagglutination inhibition assay.

Results
No association was observed between serologically documented
maternal exposure to influenza and bipolar disorder in offspring.
However, maternal serological influenza exposure was related to a
significant fivefold greater risk of bipolar disorder with psychotic
features.

Conclusions
The results suggest that maternal influenza exposure may
increase the risk for offspring to develop bipolar disorder with
psychotic features. Taken together with earlier associations between
prenatal influenza exposure and schizophrenia, these results may suggest
that prenatal influenza is a risk factor for psychosis rather than for a
specific psychotic disorder diagnosis.