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Age–period–cohort analysis of the incidence of schizophrenia in Scotland

  • Noriyoshi Takei (a1), Glyn Lewis (a1), Pak C. Sham (a1) and Robin M. Murray (a1)
Synopsis
Synopsis

Studies examining a possible decline in the incidence of schizophrenia over the last two to three decades have paid little attention to the possible role of birth cohort effects. We collected data on a Scottish national sample of all schizophrenic patients, admitted for the first time between 1966 and 1990 (N = 11348; male = 6301). In an Age–Period–Cohort analysis, a full model, incorporating three factors, had a substantially better fit to the data than other models (especially, an Age–Period model), providing clear evidence of the presence of a cohort effect. After adjustment for the effects of age and period, there was a 55% reduction in the rate of schizophrenia in men and a 39% fall in the number of women over the 50-year birth period from 1923 to 1973. The marked decline in the first admission rates observed in Scotland cannot, however, be attributed entirely to this cohort effect. Rather, a greater proportion of the declining first admission rates (88%) is ascribed to the period effect (i.e. artefactual or causally related cross-sectional effects). Nevertheless, the fact that a birth-cohort effect accounts for part of the declining incidence, suggests that causal environmental factors operating early in life have been diminishing in intensity.

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Corresponding author
1Address for correspondence: Dr Noriyoshi Takei, Genetics SectionDepartment of Psychological MedicineInstitute of Psychiatry and King's College HospitalDe Crespigny ParkLondon SE5 8AF.
References
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Adami H., Bergstrom R., Sparen P. & Baron J. (1993). Increasing cancer risk in younger birth cohorts in Sweden. Lancet 341, 773777.
Akbairian S., Vinuella A., Kim J. J., Potkin S. G., Bunney W. E. & Jones E. G. (1993). Distorted distribution of nicotinamide-adenine dinucleotide phosphate-diaphorase neurons in temporal lobe of schizophrenics implies anomalous cortical development. Archives of General Psychiatry 50, 178187.
Bamrah J. S., Freeman H. L. & Goldberg D. P. (1991). Epidemiology of schizophrenia in Salford, 1974–84. British Journal of Psychiatry 159, 802810.
Benarde M. A. & Weiss W. (1977). A cohort analysis of pancreatic cancer, 1939–1969. Cancer 39, 12601263.
Bracha H. S., Torrey E. F., Gottesman I. I., Bigelow L. B. & Cunniff C. (1992). Second-trimester markers of fetal size in schizophrenia: a study of monozygotic twins. American Journal of Psychiatry 149, 13551361.
Breslow N. E. & Day N. E. (1987). Statistical Methods in Cancer Research. Vol. II – The Design and Analysis of Cohort Studies. IARC Scientific Publications: Lyon.
Castle D., Wessely S., Der G. & Murray R. M. (1991). The incidence operationally defined schizophrenia in Camberwell, 1965–84. British Journal of Psychiatry 159, 790794.
Clayton D. & Schifflers E. (1987 a). Models for temporal variation in cancer rates. I. age–period and age–cohort models. Statistics in Medicine 6, 449467.
Clayton D. & Schifflers, E E. (1987 b). Models for temporal variation in cancer rates. II. age–period–cohort models. Statistics in Medicine 6, 469481.
Cox B. & Skegg D. C. G. (1992). Projections of cervical cancer mortality and incidence in New Zealand: the possible impact of screening. Journal of Epidemiology and Community Health 46, 373377.
Day N. E. & Charnay B. (1982). Time trends, cohort effects, and ageing as influence on cancer incidence. In Trends in Cancer Incidence – Causes and Practical Implications (ed. Magnus K.), pp. 5165. Hemisphere Pubishing: Washington, DC.
de Alarcon J., Seagroatt V. & Goldacre M. (1990). Trends in schizophrenia. Lancet 335, 852853.
Der G., Gupta S. & Murray R. M. (1990). Is schizophrenia disappearing? Lancet 335, 513516.
Dickson W. E. & Kendell R. E. (1986). Does maintenance lithium therapy prevent recurrences of mania under ordinary clinical conditions? Psychological Medicine 16, 521530.
Eagles J. M. (1991). Is schizophrenia disappearing? British Journal of Psychiatry 158, 834835.
Eagles J. M. & Whalley L. J. (1985). Decline in the diagnosis of schizophrenia among first admissions to Scottish mental hospitals from 1969–1978. British Journal of Psychiatry 146, 151154.
Eagles J. M., Hunter D. & McCance C. (1988). Decline in the diagnosis of schizophrenia among first contacts with psychiatric services in North East Scotland, 1969–1984. British Journal of Psychiatry 152, 793798.
Frost W. H. (1939). The age selection of mortality from tuberculosis in successive decades. American Journal of Hygiene 30, 9196.
Geddes J. R., Black R. J., Whalley L. J. & Eagles J. M. (1993). Persistence of the decline in the diagnosis of schizophrenia among first admissions to Scottish hospitals from 1969 to 1988. British Journal of Psychiatry 163, 620626.
Green M. F., Satz P., Gaier D. J., Ganzell S. & Kharabi F. (1989). Minor physical anomalies in schizophrenia. Schizophrenia Bulletin 15, 9199.
Häfner H. & Gattaz W. F. (1991). Is schizophrenia disappearing? European Archives of Psychiatry and Clinical Neuroscience 240, 374376
Harrison G., Owens D., Holton T., Neison D. & Boot D. (1988). A prospective study of severe mental disorder in Afro-Caribbean patients. Psychological Medicine 18, 643657.
Harrison G., Cooper J. E. & Gancarczyk R. (1991). Changes in the administrative incidence of schizophrenia. British Journal of Psychiatry 159, 811816.
Holford T. R. (1992). Analysing the temporal effects of age, period and cohort. Statistical Methods in Medical Research 1, 317337.
Joyce P. R. (1987). Changing trends in first admissions and readmissions for mania and schizophrenia in New Zealand 1974 to 1984. Australian and New Zeland Journal of Psychiatry 21, 8286.
Kendell R. E., Malcolm D. E. & Adams W. (1993). The problem of detecting changes in the incidence of schizophrenia. British Journal of Psychiatry 162, 212218.
Lee W. C. & Lin R. S. (1990). Age–period–cohort analysis of pancreatic cancer mortality in Taiwan, 1971–1986. International Journal of Epidemiology 19, 839847.
MacMahon B. & Terry W. B. (1958). Application of cohort analysis to the study of time trends in neoplastic disease. Journal of Chronic Diseases 7, 2435.
McNeil T. F. & Kaij L. (1978). Obstetric factors in the development of schizophrenia. In The Nature of Schizophrenia (ed. Wynne C., Cromwell R. L. and Matthyss S.), pp. 3851. John Wiley and Sons: New York.
Mednick S. A., Machon R. A., Huttunen M. O. & Bonett D. (1988). Adult schizophrenia following prenatal exposure to an influenza epidemic. Archives of General Psychiatry 45, 189192.
Moens G. F. G., van Oortmarssen G. J., Honggokoesoemo S., van de Voorde H. (1987). Birth cohort analysis of suicide mortality in Belgium 1954–1981 by a graphic and a quantitative method. Acta Psychiatrica Scandinavica 76, 450455.
Munk-Jørgensen P. (1986). Decreasing first admission rates of schizophrenia among males in Denmark from 1970 to 1984. Acta Psychiatrica Scandinavica 73, 645650.
Munk-Jørgensen P. & Jørgensen P. (1986). Decreasing rates of first admission diagnoses of schizophrenia among females in Denmark 1970–84. Acta Psychiatrica Scandinavica 74, 379383.
Murphy E., Lindesay J. & Grundy E. (1986). 60 years of suicide in England and Wales: a cohort study. Archives of General Psychiatry 43, 969976.
Murray R. M. (1994). Neurodevelopmental schizophrenia: the rediscovery of dementia praecox. British Journal of Psychiatry 165 (suppl. 25), 612.
Murray R. M. & Lewis S. W. (1987). Is schizophrenia a neuro-developmental disorder? British Medical Journal 295, 681682.
Murray R. M., Gupta S. & Der G. (1990). Trends in schizophrenia. Lancet 335, 1214.
Newman S. C. & Dyck R. J. (1988). On the age–period–cohort analysis of suicide rates. Psychological Medicine 18, 677681.
O'Callaghan E., Sham P., Takei N., Glover G. & Murray R. M. (1991). Schizophrenia after prenatal exposure to 1957 A2 influenza epidemic. Lancet 337, 12481250.
Parker G., O'Donnell M. & Walter S. (1985). Changes in the diagnoses of the functional psychoses associated with the introduction of lithium. British Journal of Psychiatry 146, 377382.
Royal Statistical Society (1985). The GLIM System Release 3.77 Manual (ed. Payne C. D.). NAG: Oxford.
Scotto J., Pitcher H. & Lee J. A. H. (1991). Indications of future decreasing trends in skin-melanoma mortality among whites in the United States. International Journal of Cancer 49, 490497.
Surtees P. G. & Duffy J. C. (1989). Suicide in England and Wales 1946–1985: an age–period–cohort analysis. Acta Psychiatrica Scandinavica 79, 216223.
Susser E. S. & Lin S. P. (1992). Schizophrenia after prenatal exposure to the Dutch hunger winter of 1944–45. Archives of General Psychiatry 49, 983988.
Susser M. & Stein Z. (1962). Civilization and peptic ulcer. Lancet i, 115119.
Takei N., Sham P. C., O'Callaghan E., Glover G. & Murray R. M. (1995). Schizophrenia: increased risk associated with winter and city birth. A case-control study in 12 regions within England and Wales. Journal of Epidemiology and Community Health 49, 106107.
van Os J., Galdos P., Lewis G., Bourgeois M. & Mann A. (1993). Schizophrenia sans frontières: concepts of schizophrenia among French and British psychiatrists. British Medical Journal 307, 489492.
Waddington J. L. & Youssef H. A. (1994). Evidence for a gender-specific decline in the rate of schizophrenia in rural Ireland over a 50-year period. British Journal of Psychiatry 164, 171176.
Weinberger D. R. (1987). Implications of normal brain development for the pathogenesis of schizophrenia. Archives of General Psychiatry 44, 660669.
Wickramaratne P. J., Weissman M. M., Leaf P. J. & Holford R. (1989). Age, period and cohort effects on the risk of major depression: results from five United States communities. Journal of Clinical Epidemiology 42, 333343.
World Health Organization. (1978). Mental Disordes: Glossary and Guide to Their Classification in Accordance with the Ninth Revision of the International Classification of Diseases (ICD-9). WHO: Geneva.
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Psychological Medicine
  • ISSN: 0033-2917
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