Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Email this article to a Colleague Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Add to My Articles & Searches Download to citation manager Citing Articles via Google Scholar Articles by HAUKKA, J. Articles by LÖNNQVIST, J. Search for Related Content PubMed Citation Articles by HAUKKA, J. Articles by LÖNNQVIST, J. Schizophrenia Spectrum Disorders

Early Onset of Schizophrenia

To the Editor: We read with great interest the article by Carole Di Maggio, M.D., and her colleagues (1). Although the study presented some interesting data about decreasing age at onset of schizophrenia, it also raised some questions about the interpretation and analyses of the data. The authors presented retrospective data for medical records (N=877) from 1976, 1986, and 1996. Individuals in the study were divided into three birth cohorts: 1905–1944, 1945–1964, and 1965–1984. However, the significant decrease in age at onset through time could be due to bias caused by the different age structures of the cohorts. Individual ages of the subjects in the 1905–1944 cohort were from 32 to 91 years, the subjects in the 1945–1964 cohort were aged 12 to 51 years, and the subjects in the 1965–1984 cohort were aged 1 to 31 years. Thus, all persons who died before the age of 32 could not be part of the 1905–1944 cohort. This might have been an important source of bias in the study because mortality is greater for patients with schizophrenia, but at the population level, the standardized mortality ratio for schizophrenia decreases exponentially with age (2). Only patients with illness onset before age 32 could be present in the youngest cohort.

We calculated mean ages at onset on the basis of our data (3) for cohorts from 1950–1955 (N=4,023) and 1956–1961 (N=2,941), with follow-up assessments made, respectively, at 1969–1978 and 1975–1984. The mean ages at onset were 21.8 and 21.9 years. We suggest that the data presented by Dr. Di Maggio and colleagues should be reanalyzed with consideration of the different age structures.

References

1. Di Maggio C, Martinez M, Ménard JF, Petit M, Thibaut F: Evidence of a cohort effect for age at onset of schizophrenia. Am J Psychiatry 2001; 158:489-492[Abstract/Free Full Text]
2. Brown S: Excess mortality of schizophrenia: a meta-analysis. Br J Psychiatry 1997; 171:502-508[Abstract/Free Full Text]
3. Suvisaari J, Haukka JK, Tanskanen AJ, Lönnqvist JK: Decline in the incidence of schizophrenia in Finnish cohorts born from 1954 to 1965. Arch Gen Psychiatry 1999; 56:733-740[Abstract/Free Full Text]

Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Email this article to a Colleague Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Add to My Articles & Searches Download to citation manager Citing Articles via Google Scholar Articles by HAUKKA, J. Articles by LÖNNQVIST, J. Search for Related Content PubMed Citation Articles by HAUKKA, J. Articles by LÖNNQVIST, J. Schizophrenia Spectrum Disorders

Get information about faster international access.

Privacy Policy

Copyright © 2002 American Psychiatric Association. All rights reserved.

Home | Search | Current Issue | Past Issues | Subscribe | All APPI Journals | Help | Contact Us