1. The psychosis in African and
Caribbean origin populations
Prof Kwame McKenzie MD

2. Searching for answers for my
patients
 Is
schizophrenia
more common
in Black
people?
 If so why?
+

3. 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.
+

4. +

5. African and Caribbean origin
+

6. 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

7. Meta-analysis – schizophrenia
incidence .
Selten & Cantor Graae Am J Psychiatry. 2005 Jan;162(1):12-24
+

8. 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

9. Two camps
+
 Biological Social
 Professional view Community

10. Biological camp
+

11. Genetics – highly heritable
+

12. 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
+

13. Obstetrics
+
 Winter and spring births more likely to develop schizophrenia
 could be due to viral infection or vitamin D

14. Swedish study
+

15. 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.
+

16. 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

17. +

18. Social camp
+

19. 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
+

20. Stress important
 Increased risk of schizophrenia if you…
 Live in neighborhoods that are stressful
 Have numerous daily hassles
+

21. Racism risk factor for
psychosis
Estimated prevalence of psychosis
All Ethnic Minority Groups
4.0%
3.0%
2.0%
+ 1.0%
0.0%
No Verbal Physical* No Some Most*
only*
Racial harassment British employers discriminate
 Karlsenn et al Psychological Medicine 2005 Sept 29-1-9

22. 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

23. 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
+

24. Genetic risk amplifies biological
and social risk
+

25. Incidence of psychosis by ethnicity
and social cohesion
80
Predicted incidence rate (per 100,000
70
60
person-years)
50
40 White
BME
30
20
+ 10
0
Low Medium High
Social cohesion and trust (ward-level)
25

26. A new science
 Mind not the Brain
 Epi-genetics not genetics
 Social impacts on biological mechanisms
+

27. 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

28. 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

29. 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

30. 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
+

31. 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
+

32. 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

33. 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

34. Thank you
+