[Could the fetus' exposure to influenza increase the risk of schizophrenia in adult life?].
BACKGROUND
Epidemiological studies indicate the existence of various environmental factors, which elevate the risk of schizophrenia in adult life. Influenza infection is a widely discussed causal factor in the relation to schizophrenia. The paper is a review of the studies on the theme of exposition to viral infections in foetal life--in connection with schizophrenia morbidity in adult life. Many of such studies, and yet not all of them show such a relationship.


OBJECTIVE
The aim of our study was to find the effect of influenza exposition in foetal life on the increase in schizophrenia morbidity of the Polish population, by applying the seasonal decomposition method.


METHODS
All persons discharged from hospitals in Poland with a diagnosis of schizophrenia in the years 1997-2000 were taken up for the study. The data on the population births in the given months of the period 1964-1984 was also used. Monthly indices of the number of births of patients with a diagnosis of schizophrenia per 10,000 live births in the general population of men and women was applied in order to eliminate the seasonal variability due to the unstable number of births in the general population. The number of influenza cases in Poland was divided by the number of inhabitants and multiplied by 10,000 thus forming indices of influenza cases in the subsequent months of the period studied. The seasonal decomposition method--Census I--was used for the basic analyses--this being one of the methods of time interval analyses available in the Statistica programme.


RESULTS
The study results show that exposition to influenza infections 2-4 months prior to birth may be a risk factor in schizophrenia development in adult life.
Bembenek
Andrzej
A
I Klinika Psychiatryczna IPiN w Warszawie.
D000328:Adult; D005260:Female; D006801:Humans; D007251:Influenza, Human / Q000150:complications*; D008297:Male; D008875:Middle Aged; D011044:Poland / Q000453:epidemiology; D011247:Pregnancy; D011251:Pregnancy Complications, Infectious / Q000453:epidemiology*; D011297:Prenatal Exposure Delayed Effects; D012042:Registries; D012189:Retrospective Studies; D012307:Risk Factors; D012559:Schizophrenia / Q000453:epidemiology* / Q000821:virology*; D012621:Seasons; D013997:Time Factors