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Gender-Specific Changes Since 1900 in the Season-of-Birth Effect in Schizophrenia

Published online by Cambridge University Press:  02 January 2018

John M. Eagles*
Affiliation:
Royal Cornhill Hospital, Aberdeen AB9 2ZH
David Hunter
Affiliation:
Aberdeen Psychiatric Case Register, Royal Cornhill Hospital
John R. Geddes
Affiliation:
Royal Edinburgh Hospital, Edinburgh
*
Dr Eagles, Royal Cornhill Hospital, Cornhill Road, Aberdeen AB9 2ZH. Fax: 01224-404484

Abstract

Background

It was hypothesised that the size of the season-of-birth effect may have decreased in tandem with the apparent decline in the incidence of schizophrenia.

Method

Through the Aberdeen Psychiatric Case Register, subjects were identified who had been diagnosed as schizophrenic and had been born between 1900 and 1969. The ratio of winter/spring to summer/autumn births was compared across the seven decades for both sexes together, for men, and for women.

Results

For the 1935 men, but not for the 1620 women, there was a highly significant increase (P = 0.0009) in season-of-birth effect.

Conclusion

Non-seasonal factors have contributed to a declining incidence of schizophrenia in both sexes. ‘Seasonal’ factors to which female foetuses are more susceptible than male foetuses (such as infection or malnutrition) have also decreased in frequency, severity, or both, but this has not happened with factors affecting males, leading to an increase of their season-of-birth effect.

Information

Type
Papers
Copyright
Copyright © 1995 The Royal College of Psychiatrists 

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