Scandinavian Journal of Public Health
Volume 40, Issue 1, 2012, Pages 43-50

Familial aggregation of schizophrenia: The moderating effect of age at onset, parental immigration, paternal age and season of birth (Article)

Svensson A.C.* , Lichtenstein P. , Sandin S. , Öberg S. , Sullivan P.F. , Hultman C.M.
  • a Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden
  • b Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden
  • c Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden
  • d Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden
  • e Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Department of Genetics, University of North Carolina, Chapel Hill, North Carolina, Stockholm, Sweden
  • f Department of Neuroscience Psychiatry, Ulleraåker, Uppsala University, Uppsala, Sweden

Abstract

Aims: An abundance of evidence has firmly established the familial aggregation of schizophrenia. The aim of this study was to examine how age at onset, parental characteristics and season of birth modify the familiality in schizophrenia. Methods: A population-based cohort was created by linking the Swedish Multi-Generation and Hospital Discharge Registers. Among 5,075,998 full siblings born between 1932 through to 1990, 16,346 cases of schizophrenia were identified. Familial aggregation was measured by the sibling recurrence-risk ratio, defined as the risk of schizophrenia among full siblings of schizophrenia patients compared with the risk among siblings of unaffected people. Results: We found a statistically significantly lower recurrence-risk ratio in siblings of later onset cases (7.2; 95% confidence interval (95% CI) 6.7–7.9) than of early onset cases (10.8; 95% CI 9.4–12.2). A lower recurrence-risk ratio was observed among offspring to fathers above 40 years (6.3; 95% CI 5.3–7.3) as compared with offspring of younger fathers (8.6; 95% CI 8.0–9.3). Further, among offspring to parents born outside Sweden the recurrence-risk ratio was statistically significantly lower (maternal immigrants 4.8; 95% CI 4.0–5.7, paternal immigrants 5.7; 95% CI 4.6–6.9) than among offspring to parents born in Sweden. Conclusions: The familial aggregation of schizophrenia was reduced by higher age at onset, advancing paternal age and immigrant status of parents. © 2011, Associations of Public Health in the Nordic Countries Regions. All rights reserved.

Author Keywords

Migration age at onset Paternal age recurrence-risk ratio schizophrenia familial aggregation

Index Keywords

genetics Parents sibling birth Registries schizophrenia register human middle aged statistics Siblings Aged Seasons season Young Adult Sweden Humans Adolescent male female Aged, 80 and over risk factor Age of Onset Risk Factors paternal age Article adult migration Pedigree Emigration and Immigration Case-Control Studies Parturition case control study onset age parent
Link
https://www.scopus.com/inward/record.uri?eid=2-s2.0-84856756346&doi=10.1177%2f1403494811420485&partnerID=40&md5=5aa7af418086986659c437b911e22898
DOI: 10.1177/1403494811420485
ISSN: 14034948
Cited by: 18
Original Language: English