Prenatal exposure to the 1957 influenza epidemic and adult schizophrenia: a follow-up study.
BACKGROUND
We investigated the hypothesis that prenatal exposure to the 1957 A2 influenza increases the risk of schizophrenia in adulthood.


METHODS
We traced a cohort of individuals known to have been exposed to the 1957 influenza epidemic during gestation and an unexposed cohort matched for period of gestation and hospital of birth. Follow-up information on psychiatric illness in subjects was sought from two sources: maternal interview and psychiatric hospital admission data.


RESULTS
Follow-up information was obtained on 54% of the sample: 238 subjects from the influenza-exposed group and 287 subjects from the unexposed group. There was no increased risk of schizophrenia among the exposed cohort compared to the unexposed cohort (relative risk 1.1; 95% Cl 0.41-2.95), although there was an increase in depressive illness (relative risk 1.59; 95% Cl 1.15-2.19).


CONCLUSIONS
The association between prenatal influenza and an increased risk of schizophrenia in adulthood has thus far been found only in population-based data and is not supported by the present observational study which has information about exposure and outcome in individuals.
Cannon
M
M
Cotter
D
D
Coffey
V P
VP
Sham
P C
PC
Takei
N
N
Larkin
C
C
Murray
R M
RM
O'Callaghan
E
E
D015331:Cohort Studies; D004196:Disease Outbreaks; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D015994:Incidence; D007251:Influenza, Human / Q000453:epidemiology*; D007494:Ireland / Q000453:epidemiology; D011247:Pregnancy; D011295:Prenatal Care; D011297:Prenatal Exposure Delayed Effects; D012189:Retrospective Studies; D012559:Schizophrenia / Q000209:etiology*