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Arch Gen Psychiatry. 2004 Oct;61(10):985-9.

Summer birth and deficit schizophrenia: a pooled analysis from 6 countries.

Author information

1
Department of Psychiatry, School of Medicine, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, USA

Abstract

BACKGROUND:

In some reports, summer birth has been associated with deficit schizophrenia. Deficit schizophrenia and nondeficit schizophrenia also differ in several other ways.

OBJECTIVE:

To conduct a combined analysis of the published and unpublished data sets from the northern hemisphere that relate deficit and nondeficit schizophrenia to month of birth.

DATA SOURCES:

Studies of season of birth in which it was possible to make a deficit/nondeficit categorization.

STUDY SELECTION:

Published studies with samples of convenience and all known population-based studies with the deficit/nondeficit categorization were included. The studies came from 6 countries.

DATA EXTRACTION:

Three published studies of samples of convenience, 2 population-based prevalence studies, and 5 population-based studies that approximated incident samples were included. Month of birth was compared for deficit and nondeficit schizophrenia, using meta-analytic fixed-effects models.

DATA SYNTHESIS:

A group x month goodness-of-fit chi2 showed a significant difference between deficit and nondeficit subjects in season of birth (P < .001) in the studies that approximated incidence. This difference was largely due to an increase in deficit schizophrenia births in June and July (odds ratio, 1.9; 95% confidence interval, 1.3-2.9). Similar results were found in the prevalence studies. A similar pattern was found in 2 of the 3 samples of convenience, but when combined, these 3 samples did not show a significant deficit/nondeficit difference.

CONCLUSIONS:

Deficit schizophrenia has a season of birth pattern that differs from that of nondeficit schizophrenia. This analysis supports the notion of a separate disease within schizophrenia.

PMID:
15466671
DOI:
10.1001/archpsyc.61.10.985
[Indexed for MEDLINE]

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