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Incidence of schizophrenia in ethnic minorities in London: ecological study into interactions with environment

BMJ 2001; 323 doi: https://doi.org/10.1136/bmj.323.7325.1336 (Published 08 December 2001) Cite this as: BMJ 2001;323:1336

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Incidence of schizophrenia in ethnic minorities in London: the challenges of ecological studies.

Incidence of schizophrenia in ethnic minorities in London: the
challenges of ecological studies.

Editor- Boydell et al’s 1 finding that incidence rates of
schizophrenia are inversely proportional to the population density of
ethnic minority groups are of great interest as they have major
implications for the understanding of the mental health of ethnic minority
populations and service provision. However it is crucial that the
interplay between complex social factors should undergo rigorous
sociological analysis and results not generalised but interpreted with
caution2, 3 as they have the potential to be manipulated as a political
tool – for example the dispersal of refugee populations.

The sample population from Camberwell, South East London comprises
persons with diverse socio-economic and demographic characteristics. The
ethnic minority population being predominantly of African and African-
Caribbean origin with significant generational differences as well as
diverse and mobile migrant and refugee populations, with varied risks of
psychiatric morbidity between groups and across wards 3.

The “ecological” identity of a population involves a community
history, name, awareness of certain common interests by residents and the
presence of businesses or organisations oriented to the local community 4.
Given Camberwell’s small “neighbourhood” landmass of approximately 3 miles
radius, it is envisaged that daily activities (e.g. shopping, education,
employment) would overlap the 15 electoral wards, as would the influence
of environmental exposure. A broader study involving all / or South
London boroughs may more accurately reflect the ecological characteristics
and their influences.
Ecological communities respond differentially to persons with severe
mental illness determined by community traits, institutions and communal
beliefs, with higher rates of extrusion (“extrusion bias”) occurring to
persons with less social cohesion (e.g. diminished family, religious,
business or social frameworks). Extrusion may occur through increased
involuntary admissions or lowered referral thresholds for those with
serious psychiatric illness. This may also be influenced by ethnicity,
gender, age, social status and generational difference.

Although White minority groups (e.g. Irish and East European), were
omitted from analysis in this study, researchers have observed similar
phenomena in parts of Chicago with over 26% ethnic minority 4. Hence, one
may expect increased incidence rates of schizophrenia among the White
population in areas of London (Brent and Newham) with over 50% ethnic
minority populations (but not among wealthy expatriates living abroad).

Ecological approaches to epidemiological research, provide
descriptive properties of groups, however a common criticism is that they
fail to capture the personal attributes and experiences of the individual,
fundamental to a study of complex socio-environmental factors. Ethnic
minority status does not mean social experiences are predominantly
discriminatory or a result of isolation. Group correlations may therefore
be strong yet show no true relationship between social variables.

While isolation, discrimination and racial life events have been
found to be associated with the onset of anxiety and depressive illness,
the relationship with schizophrenia remains unclear 5. Multicentre
longitudinal studies are needed at an individual level to clarify these
processes. Such studies will be vital in guiding local and national policy
and mental health service provision for ethnic minority populations.

Declaration of interest: none

Oyedeji Ayonrinde

Specialist registrar and Honorary Research Worker in Cultural Psychiatry
Maudsley Hospital / Health Services Research Department, Institute of
Psychiatry
Denmark Hill, SE5 8AZ

o.ayonrinde@iop.kcl.ac.uk

Samantha Maingay

Medical Sociologist

Health Services Research Department,
Institute of Psychiatry,
Denmark Hill, SE5 8AF

1. Boydell J, van Os J, McKenzie K et al. Incidence of schizophrenia
in ethnic minorities in London: ecological study into interactions with
environment. BMJ 2001;323:1336-1338

2. Muntaner C. Social mechanisms, race and social epidemiology. American
Journal of Epidemiology 1999;150:121-126

3. Neelman J, Wilson-Jones, Wessely S. Ethnic density and deliberate self
harm; a small area study in south east London. Journal of Epidemiology and
Community Health 2001; 55:85-90.

4. Levy L, Rowitz L. The Ecology of Mental Disorder. Behavorial
Publications, New York, 1973.

5. Bhugra D, Ayonrinde O, Mallett R, Leff J. Measurement of racial life
events in schizophrenia: development of a new schedule- a pilot study.
International Journal of Methods in Psychiatric Research 2001; 10 (3) 140-
146.

Competing interests: No competing interests

18 December 2001
Oyedeji Ayonrinde
Specialist Registrar and Honorary Research Worker, Medical Sociologist
Samantha Maingay
Maudsley Hospital SE5 8AZ, Institute of Psychiatry SE5 8AF