dr. kwame mckenzie - psychosis in black populations
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The psychosis in African and
Caribbean origin populations
Prof Kwame McKenzie MD
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Searching for answers for my
patients
Is
schizophrenia
more common
in Black
people?
If so why?
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African and Caribbean origin
populations
Third largest visible minority in Toronto in 2006.
352,200 people
16.2% of Toronto's visible minority population,
6.9% of its total population.
55.4% of the Black population are foreign-born
of those who are foreign born 55.1% came from either
Jamaica, Trinidad and Tobago, or Ghana.
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African and Caribbean origin
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Schizophrenia and psychosis
0.5 -1% risk in lifetime
Costs billions to Canada but main impact on
individuals and families
Symptoms – delusions, hallucinations, problems
with control of thought, social withdrawal, cognitive
impairment, depression
often starts in teenage years
30% symptomatic recovery
Majority not working
Die 25 – 30 years younger
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Meta-analysis – schizophrenia
incidence Selten & Cantor Graae Am J Psychiatry. 2005 Jan;162(1):12-24.
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Migrants risk of schizophrenia Selten & Cantor Graae Am J Psychiatry. 2005 Jan;162(1):12-24.
Migrant group Relative risk 95% CI
first generation 2.7 2.3-3.2
second generation 4.7 1.5-13.1
“black” migrants 4.8 3.7-6.2
“white” migrants 2.3 1.7-2.9
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Two camps
Biological Social
Professional view Community
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Biological camp
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Genetics – highly heritable
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Obstetrics
Obstetric problems common
Non specific risk factor with small impact on schizophrenia risk
Hypoxia before or during birth may impact on brain development increasing risk of later schizophrenia
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Obstetrics
Winter and spring births more likely to develop schizophrenia
could be due to viral infection or vitamin D
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Swedish study
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Cannabis:
analysis of best studies
Cannabis 2X increase individual’s risk for later
schizophrenia
Elimination of cannabis use would reduce the
population incidence of schizophrenia by 8%,
But cannabis neither a sufficient nor a necessary
cause for psychosis.
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Biological theory: changes
in structure
Biological insult to the developing brain leads to problems later on.
Decrease in grey matter, enlargement of ventricles, focal alteration of white matter
Pathways of neuro-transmitter dopamine in the limbic system and parts of the pre-frontal cortex involved
Increase in dopamine synthesis, dopamine release, and synaptic dopamine
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Social camp
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Childhood
Social factors increase the risk of developing
schizophrenia:
Separation from parents for more than a year in
childhood
Social adversity in childhood (more adversity more
risk)
Psychological trauma / Bullying / poverty
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Stress important
Increased risk of schizophrenia if you…
Live in neighborhoods that are stressful
Have numerous daily hassles
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Racism risk factor for
psychosis
Estimated prevalence of psychosisEstimated prevalence of psychosis
All Ethnic Minority Groups
0.0%
1.0%
2.0%
3.0%
4.0%
No Verbal
only*
Physical* No Some Most*
Racial harassment British employers discriminate
Karlsenn et al Psychological Medicine 2005 Sept 29-1-9
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Urban environment
Increased rates of psychosis in
cities not due to drift alone
Being born and brought up in a
city are risk factors.
The risk increases as the size
of the city increases.
Longer you live in a city when
you are young, the higher your
risk for developing psychosis
22
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Social model
Schizophrenia result of trauma and stress
The more social stress, the higher the risk
Problematic psychological mechanisms may start
in childhood
Adult stress on top of childhood mechanisms
leads to psychosis
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Genetic risk amplifies biological
and social risk
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25
0
10
20
30
40
50
60
70
80
Social cohesion and trust (ward-level)
Pre
dic
ted
inci
den
ce r
ate
(per
100
,000
per
son
-yea
rs)
White
BME
Low Medium High
Incidence of psychosis by ethnicity
and social cohesion
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A new science
Mind not the Brain
Epi-genetics not genetics
Social impacts on biological mechanisms
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How does all this cause mental illness
Mental illness lies in the biological and
psychological mechanisms that adapt us to the
environment
Symptoms are behaviors and thoughts that
reflect body trying to adapt
Illness reflects differential acceptance by society
of different types of adaptation
Our biology and psychology are linked
processes in adaptation
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Biological development
depends on the environment
Development of brain and mind depend on
environmental stimulation
Normal development of neuronal connectivity
depends on impacts of environment during
sensitive periods of development
Different psychological processes develop at
different times
Mechanisms that build resilience are developed
through interaction with the environment
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Molecular function mediates our
response to environment
Epi-genetics = reversible regulation of various genomic functions, occurring independently of DNA sequence,
Mediated through changes in DNA, eg. methylation and chromatin structure.
Help us develop and regulate gene function
They regulate genetic our response to environmental stimuli such as stress
Other candidates – neurogenesis and inflammation
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Early adversity may have long
term impacts
Early neglect and other environmental insults
impact stress signaling.
Causes impaired neuronal responsiveness in the
meso-limbic system and symptoms of pre-frontal
cortical dysfunction
Makes you more sensitive to stress and more likely
to produce sub-clinical psychotic symptoms
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Trajectory then mediated by
social world
Psychotic symptoms in adolescence transient and
sub-clinical
But repeated exposure to stress triggers persistent
and more severe symptoms
Social response to symptoms may cause chronicity
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Why high rates in black populations
Increased biological risk factors
Genetics in second generation
Access to obstetric care
Increased social risk factors
Separation from parents increased
Social adversity in childhood
Increased daily hassles and stress because of SES and racism
Increased urban birth and residence
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Answers for my patients
Causes of psychosis are multi-level – no one person or one thing causes psychosis
Neither patients or parents are to blame
Social and biological are linked
Problems is mind not the brain
Focusing on the mechanisms that lead to adaptation to stress and trauma offers a chance of cure as well as prevention
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Thank you
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