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Rates of treated schizophrenia and its clinical and cultural features in the population isolate of the Iban of Sarawak: a tri-diagnostic approach

Published online by Cambridge University Press:  21 January 2005

ROBERT BARRETT
Affiliation:
University of Adelaide, Department of Psychiatry, L4 Eleanor Harrald Building, Royal Adelaide Hospital, Adelaide, SA 5000, Australia; Jalan Sabu, 95000 Sri Aman, Sarawak, Malaysia; Queensland Centre for Mental Health Research, The Park, Centre for Mental Health, Wacol, Q 4076, Australia; Queensland Institute of Medical Research, P.O. Royal Brisbane Hospital, Brisbane, Q 4029, Australia; Department of Psychiatry, University of Queensland, Brisbane, Q 4029, Australia
PETER LOA
Affiliation:
University of Adelaide, Department of Psychiatry, L4 Eleanor Harrald Building, Royal Adelaide Hospital, Adelaide, SA 5000, Australia; Jalan Sabu, 95000 Sri Aman, Sarawak, Malaysia; Queensland Centre for Mental Health Research, The Park, Centre for Mental Health, Wacol, Q 4076, Australia; Queensland Institute of Medical Research, P.O. Royal Brisbane Hospital, Brisbane, Q 4029, Australia; Department of Psychiatry, University of Queensland, Brisbane, Q 4029, Australia
EDWARD JERAH
Affiliation:
University of Adelaide, Department of Psychiatry, L4 Eleanor Harrald Building, Royal Adelaide Hospital, Adelaide, SA 5000, Australia; Jalan Sabu, 95000 Sri Aman, Sarawak, Malaysia; Queensland Centre for Mental Health Research, The Park, Centre for Mental Health, Wacol, Q 4076, Australia; Queensland Institute of Medical Research, P.O. Royal Brisbane Hospital, Brisbane, Q 4029, Australia; Department of Psychiatry, University of Queensland, Brisbane, Q 4029, Australia
DEREK NANCARROW
Affiliation:
University of Adelaide, Department of Psychiatry, L4 Eleanor Harrald Building, Royal Adelaide Hospital, Adelaide, SA 5000, Australia; Jalan Sabu, 95000 Sri Aman, Sarawak, Malaysia; Queensland Centre for Mental Health Research, The Park, Centre for Mental Health, Wacol, Q 4076, Australia; Queensland Institute of Medical Research, P.O. Royal Brisbane Hospital, Brisbane, Q 4029, Australia; Department of Psychiatry, University of Queensland, Brisbane, Q 4029, Australia
DAVID CHANT
Affiliation:
University of Adelaide, Department of Psychiatry, L4 Eleanor Harrald Building, Royal Adelaide Hospital, Adelaide, SA 5000, Australia; Jalan Sabu, 95000 Sri Aman, Sarawak, Malaysia; Queensland Centre for Mental Health Research, The Park, Centre for Mental Health, Wacol, Q 4076, Australia; Queensland Institute of Medical Research, P.O. Royal Brisbane Hospital, Brisbane, Q 4029, Australia; Department of Psychiatry, University of Queensland, Brisbane, Q 4029, Australia
BRYAN MOWRY
Affiliation:
University of Adelaide, Department of Psychiatry, L4 Eleanor Harrald Building, Royal Adelaide Hospital, Adelaide, SA 5000, Australia; Jalan Sabu, 95000 Sri Aman, Sarawak, Malaysia; Queensland Centre for Mental Health Research, The Park, Centre for Mental Health, Wacol, Q 4076, Australia; Queensland Institute of Medical Research, P.O. Royal Brisbane Hospital, Brisbane, Q 4029, Australia; Department of Psychiatry, University of Queensland, Brisbane, Q 4029, Australia

Abstract

Background. We present results of a study of treated rates of schizophrenia among the Iban of Sarawak, Malaysia. Most Iban live in longhouses, each comprising a kindred group of up to 300 individuals. Cultural practices such as minimal intermarriage with members of adjacent ethnic groups and in-depth genealogical knowledge make them a population suitable for genetic investigation. Iban culture is conducive to a focus on symptoms and illness, and to patterns of treatment-seeking behaviour that are enthusiastic and persistent.

Method. We identified all known cases of psychotic disorder within a defined catchment area based on an exhaustive survey of available medical records. From corresponding Malaysian census data (91056 persons), we report rates of treated schizophrenia in the Iban population, using three diagnostic systems, as well as the demographic and clinical characteristics of these individuals.

Results. The most frequent presenting complaints were insomnia and aggression. We found higher treated rates for narrowly defined schizophrenia among males, but no significant gender difference for age of onset. Estimates of treated rates to age 55 years (per 10000) for narrow schizophrenia were 41·9 (ICD-10), 56·5 (DSM-IV), and 83 (RDC), while the rates for broad schizophrenia were 105·5, 103·2, and 107·5 respectively.

Conclusions. Treated rates of schizophrenia were higher than the reported prevalence for many populations at risk, including many small-scale societies, although different methodological approaches may partly explain these findings. Given the cultural patterns of Iban treatment-seeking behaviour, treated rates of schizophrenia reported here may closely approximate the population prevalence of this disorder.

Type
Research Article
Copyright
© 2004 Cambridge University Press

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