This Article  • Full text  • PDF  • Reply to article  • Send to a friend  • Save in My Folder  • Save to citation manager  • Permissions  Citing Articles  • Citation map  • Citing articles on HighWire  • Citing articles on Web of Science (61)  • Contact me when this article is cited  Related Content  • Similar articles in this journal  Topic Collections  • Schizophrenia  • Alert me on articles by topic  Social Bookmarking   What's this?

Jaana M. Suvisaari, MD; Jari K. Haukka, PhD; Antti J. Tanskanen, BSc; Jouko K. Lönnqvist, MD, PhD

Arch Gen Psychiatry. 1999;56:733-740.

Background  The declining incidence of schizophrenia observed in several countries is believed by many to merely reflect methodological problems in the studies performed. We report the first nationwide historical cohort study of changes in the incidence of schizophrenia, in which many of the previous methodological problems were overcome.

Methods  We used the Finnish Population Register to identify everyone born in Finland from 1954 to 1965. These persons were followed up from their 16th to their 26th birthdays, and all cases of schizophrenia (International Classification of Diseases, Eighth Revision andInternational Classification of Diseases, Ninth Revision code 295) that emerged were identified from the National Hospital Discharge Register, the Pension Register, and the Free Medicine Register. Persons for whom an age of onset could be defined were included in the analyses (n=5645). We used the Poisson regression model to estimate the effects of age, sex, birth cohort, period of diagnosis, and season of birth on the incidence of schizophrenia. The relative importance of cohort and period were assessed using an age-period-cohort model.

Results  The incidence declined significantly in each successive cohort, from 0.79 to 0.53 per 1000 among males and from 0.58 to 0.41 per 1000 among females. The effects of cohort and period on the change were both significant.

Conclusions  The incidence of schizophrenia has declined in Finland. This was partly caused by confounding factors, as reflected in the significant period effect. The significant birth cohort effect suggests that the intensity or frequency of one or more risk factors for schizophrenia has decreased.

From the Department of Mental Health and Alcohol Research, National Public Health Institute, Helsinki, Finland.

CiteULike    Connotea    Del.icio.us    Digg    Reddit    Technorati    Twitter     What's this?

THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES

Schizophrenia: A Concise Overview of Incidence, Prevalence, and Mortality
McGrath et al.
Epidemiol Rev 2008;30:67-76.
ABSTRACT | FULL TEXT  

Determinants and Outcomes of Serious Attempted Suicide: A Nationwide Study in Finland, 1996-2003
Haukka et al.
Am J Epidemiol 2008;167:1155-1163.
ABSTRACT | FULL TEXT  

Incidence of Schizophrenia in a Nationwide Cohort of Patients With Type 1 Diabetes Mellitus
Juvonen et al.
Arch Gen Psychiatry 2007;64:894-899.
ABSTRACT | FULL TEXT  

Lifetime Prevalence of Psychotic and Bipolar I Disorders in a General Population
Perala et al.
Arch Gen Psychiatry 2007;64:19-28.
ABSTRACT | FULL TEXT  

Antidepressants and the Risk of Suicide, Attempted Suicide, and Overall Mortality in a Nationwide Cohort
Tiihonen et al.
Arch Gen Psychiatry 2006;63:1358-1367.
ABSTRACT | FULL TEXT  

Effectiveness of antipsychotic treatments in a nationwide cohort of patients in community care after first hospitalisation due to schizophrenia and schizoaffective disorder: observational follow-up study
Tiihonen et al.
BMJ 2006;333:224.
ABSTRACT | FULL TEXT  

Are the Cause(s) Responsible for Urban-Rural Differences in Schizophrenia Risk Rooted in Families or in Individuals?
Pedersen and Mortensen
Am J Epidemiol 2006;163:971-978.
ABSTRACT | FULL TEXT  

Heterogeneity in Incidence Rates of Schizophrenia and Other Psychotic Syndromes: Findings From the 3-Center AeSOP Study.
Kirkbride et al.
Arch Gen Psychiatry 2006;63:250-258.
ABSTRACT | FULL TEXT  

Variations in the Incidence of Schizophrenia: Data Versus Dogma
McGrath
Schizophr Bull 2006;32:195-197.
ABSTRACT | FULL TEXT  

Premorbid Intellectual Functioning in Bipolar Disorder and Schizophrenia: Results From a Cohort Study of Male Conscripts
Tiihonen et al.
Am. J. Psychiatry 2005;162:1904-1910.
ABSTRACT | FULL TEXT  

Mental disorders in prison populations aged 15-21: national register study of two cohorts in Finland
Sailas et al.
BMJ 2005;330:1364-1365.
FULL TEXT  

Cumulative incidence of mental disorders among offspring of mothers with psychotic disorder: Results from the Helsinki High-Risk Study
Niemi et al.
Br. J. Psychiatry 2004;185:11-17.
ABSTRACT | FULL TEXT  

Sex Differences in the Risk of Schizophrenia: Evidence From Meta-analysis
Aleman et al.
Arch Gen Psychiatry 2003;60:565-571.
ABSTRACT | FULL TEXT  

Fertility of Patients With Schizophrenia, Their Siblings, and the General Population: A Cohort Study From 1950 to 1959 in Finland
Haukka et al.
Am. J. Psychiatry 2003;160:460-463.
ABSTRACT | FULL TEXT  

Incidence of schizophrenia in south-east London between 1965 and 1997
BOYDELL et al.
Br. J. Psychiatry 2003;182:45-49.
ABSTRACT | FULL TEXT  

Dr. Suvisaari and Colleagues Reply
SUVISAARI et al.
Am. J. Psychiatry 2002;159:500-500.
FULL TEXT  

Early Onset of Schizophrenia
HAUKKA et al.
Am. J. Psychiatry 2002;159:322-322.
FULL TEXT  

Genome-wide scan in a nationwide study sample of schizophrenia families in Finland reveals susceptibility loci on chromosomes 2q and 5q
Paunio et al.
Hum Mol Genet 2001;10:3037-3048.
ABSTRACT | FULL TEXT  

Association of Schizophrenia With Low Maternal Body Mass Index, Small Size at Birth, and Thinness During Childhood
Wahlbeck et al.
Arch Gen Psychiatry 2001;58:48-52.
ABSTRACT | FULL TEXT  

Schizophrenia is not disappearing in south-west Scotland
ALLARDYCE et al.
Br. J. Psychiatry 2000;177:38-41.
ABSTRACT | FULL TEXT