Produced by the Royal College of Physicians of Edinburgh and Royal College of Physicians and Surgeons of Glasgow

Womb Flu link to Schizophrenia

  • Dr DJ MacIntyre, Lecturer in Psychiatry, University of Edinburgh, Edinburgh, Scotland
  • Dr D Blackwood, Professor of Psychiatry, University of Edinburgh, Edinburgh, Scotland

Summary

Research and media reports have suggested that individuals whose mothers contracted flu during pregnancy are at increased risk from developing schizophrenia in later life. How strong is this link and what, if any, impact should this have on immunisation programmes? Dr Donald MacIntyre and Dr Douglas Blackwood review the evidence.

Key Points

  • Schizophrenia is a distressing and disabling condition, affecting about 1% of the population worldwide.
  • It is caused by an interaction of genetic and environmental factors which can have their effect in utero and throughout development.
  • Maternal infections, including influenza, can modestly increase risk of developing schizophrenia.
  • Recent evidence, in line with previous work, supports this assertion.
  • The mechanism of this action is unknown, but it is probably indirect.
  • It is too early to make public health policy recommendations regarding flu vaccination.

Declaration of interests: No conflict of interests declared

Schizophrenia is a mental disorder with a very variable presentation, characterised by delusions, hallucinations and an insidious deterioration in cognitive and social functioning. It is one of the 30 leading causes of disability and mortality worldwide and affects about 1% of the UK population at some time in their lives, with an average age of onset in the mid-twenties.1

Background

Our understanding of the cause of schizophrenia is incomplete but it is certain that individual genetic make-up is very important, and in addition that the genetic make-up interacts with environmental factors to produce the disease. While genetic make-up is fixed at conception, environmental influences vary throughout the life of the individual; those that have been implicated, at one time or another, in the development of schizophrenia are numerous and diverse and their mechanisms of action are obscure. However, there is evidence that the following factors play a part in some people: being an immigrant or from an ethnic minority; maternal infection, famine or bereavement during pregnancy; being born in winter or spring; obstetric complications; being born and brought up in an urban area; and using illicit substances as a teenager.2

Womb flu link

News reports3 4 prompted by a recent paper by Dr Alan Brown and colleagues at Columbia University5 have highlighted the relationship between maternal influenza infection and an increased risk of developing schizophrenia or a related disorder.

Flu research

Sixteen years ago, Mednick and colleagues6 first reported an increased risk of schizophrenia in a study of Finnish individuals whose mothers had been in the mid-part of their pregnancy during the worldwide influenza