ENVIRONMENTAL EPIDEMIOLOGY OF PSYCHOSES: Lessons from Nottingham

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ENVIRONMENTAL EPIDEMIOLOGY OF PSYCHOSES Lessons
from Nottingham
Jouko Miettunen Department of Public Health and
Primary Care Institute of Public
Health University of Cambridge
June 17th, 2003
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PSYCHOTIC DISORDERS

• chronic, severe, and disabling brain diseases
• life-time prevalence approximately
• 1 in schizophrenia
• 1 other psychoses
• more common in urban than in rural areas
• more common in western countries

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POSSIBLE ENVIRONMENTAL RISK FACTORS

• related to urban birth or to upbringing
• population density
• stressful life-events
• air pollution
• social deprivation
• temporal order can be the opposite
• social drift?
• more healthy people may move out from deprived
  areas?

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Nottingham Health Authority Area

• about 600,000 people in 105 electoral wards
• districts of Nottingham, Ruschliffe, Broxtowe,
  Gedling and Ashfield
• several previous studies (1969-1988) on
  schizophrenia and other psychoses
• possible to estimate trends in incidence
• relatively high social deprivation and incidence
  of schizophrenia

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SAMPLES OF THE STUDY

• SIN DATA
• Schizophrenia Incidence in Nottingham
• all incidence cases of psychoses in Nottingham
  Health Authority Area 1.6.1992 - 31.5.1994
• 167 cases (166 with known address)
• ÆSOP DATA
• Aetiology and Ethnicity in Schizophrenia and
  Other Psychoses
• three-centre study (other centres are Bristol and
  South London)
• all incidence cases of psychoses in Nottingham
  Health Authority Area 1.8.1997 - 31.7.1999
• 206 cases (202 with known address)

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INDIVIDUAL VARIABLES

• DISTRIBUTIONS 1992-94 (N167) 1997-99
  (N206)
• Gender males 98 (59)
  123 (60)
• Median age 28
  y 30 y
• Diagnoses
• Narrow schizophrenia 56
  67
• Broad schizophrenia 82
  116
• Affective psychosis 85
  90
• Ethnic groups
• White 122
  (73) 159 (77)
• African-Caribbean 26 (16)
  26 (13)
• Other
  19 (11) 21 (10)

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POPULATION DATA

• Census 1991 population of Nottingham
• population at risk (16 to 64 years) 389,389
• after under-enumeration corrections 399,439
• till 1992-94 population has increased
  approximately 2 and till 1997-99 approximately
  6 from this estimate

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ELECTORAL WARD LEVEL VARIABLES

• Multiple Deprivation Index 2000
• Income
• Employment
• Housing
• Health deprivation and disability
• Education, skills and training
• Geographical access to services
• population density
• proportion of ethnic minorities

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HYPOTHESES OF THE STUDY

• Incidence of psychoses is higher in more deprived
  areas (and/or in areas with higher population
  density)
• Incidence of psychoses among ethnic minorities is
  relatively higher in areas with lower proportion
  of ethnic minorities
• lack of social support?

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CASES 1992-94
Deprivation High to low
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CASES 1997-99
Deprivation High to low
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ANNUAL INCIDENCE OF ALL PSYCHOSES BY SOCIAL
DEPRIVATION NOTTINGHAM 1992-1994
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ANNUAL INCIDENCE OF ALL PSYCHOSES BY SOCIAL
DEPRIVATION NOTTINGHAM 1997-1999
250
204
200
167
I (high)
136
150
128
II
III
100
70
69
64
IV (low)
53
39
50
29
22
20
20
19
18
16
0
ALL
white
afro-c.
others
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PLAN FOR ANALYSES

• Age-standardised rates (Nottingham as a standard)
• Two studies separately and pooled
• Results by
• Sex
• Ethnic group
• Subdiagnoses
• narrow schz, broad schz and affective psychosis
• each of the six variables in the deprivation
  score
• Poisson regression analyses

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LIMITATIONS

• Electoral ward as a unit?
• Case-ascertainment?
• Census population?
• Social deprivation scores?
• analyses can be repeated with other scores
• Causality?

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FUTURE WORK (1)

• Smaller units than electoral wards
• enumeration districts (no information on
  ethnicity)
• using e.g. principal component analysis
• Census 2001 variables are soon available
• update all the analyses with new population data
• update all the the analyses with new social
  deprivation variables
• combinations of census 1991 and 2001 variables

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FUTURE WORK (2)

• Case-control study of ÆSOP
• multilevel analyses with individual level
  variables e.g. social class
• ÆSOP is a three-centre study
• replicate the analyses in Bristol and South London

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CONCLUSIONS

• Preliminary findings
• incidence of schizophrenia is about 1.5 more
  common in the most deprived areas

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CONCLUSIONS

• Preliminary findings
• incidence of schizophrenia is about 1.5 more
  common in the most deprived areas

• Much more work is needed in this thesis and also
  elsewhere to study social deprivation and
  incidence of psychoses
• All your comments will be very helpful
• Thank You!