Influenza and Schizophrenia: Helsinki vs Edinburgh

Abstract

<h3>the Editor.—</h3> Kendell and Kemp, in the October 1989 issue of theArchives, utilized Scottish data in an attempt to replicate the intriguing findings of Mednick et al, who found an association between midtrimester maternal exposure to influenza and subsequent development of schizophrenia in the offspring. Using the Edinburgh Case Register, the study identified 242 people born with schizophrenia in 1957, and 515 people born with schizophrenia in 1955 and 1956. Kendell and Kemp found a significant excess of babies born with schizophrenia in the 3-month period in 1957 shortly after the influenza epidemic peak (a birth cohort in utero during the epidemic) compared with the expected number using the same 3- month period in the 2 previous years as a control (11 births in the 1957 3-month period vs 8 births total for the same 3-month periods in 1955 and 1956; P&lt;.05). One problem with the Kendell and Kemp