Dr Mary Rowlands, Endas

1
Dr Mary Rowlands, Endas

• DUAL DIAGNOSIS
• (CO-MORBIDITY)
• IN BRIEF

2
Important reference

• Co-existing Problems of Mental Health and
  Substance Misuse
• Dual Diagnosis
• A Review of Relevant Literature
• College Research Unit
• Vanessa Crawford
• Editor Professor Ilana Crome, 2001

3
Aims of todays course

• To raise awareness of the nature and prevalence
  of Dual Diagnosis.
• To enable participants to understand why dual
  diagnosis is complex.
• To examine brief detection screening for this
  client group.

4
Aims of todays course

• Improve knowledge of increased vulnerability in
  mentally ill to use substances sub-optimise MH
  Rx
• To challenge attitudes towards
• this client group
• Mental Health Addiction Service response in
  context that Substance Use is common in UK

5
Objectives for todays course

• To develop your skills in the brief assessment of
  individuals with a co-morbidity.
• To be able to determine differences and overlap
  between symptoms of mental health problems and
  substance misuse.
• For you to feel more confident in being able to
  manage individuals with complex needs.
• If time Department of Health funded Systematic
  Review of evidence that cannabis use increases
  risk of psychotic and affective disorders
  (June 2005-June 2006)

6
Definitions of Dual Diagnosis

• The term dual diagnosis covers a broad spectrum
  of mental health and substance misuse problems
  that an individual might experience concurrently.
  The nature of the relationship between these two
  conditions is complexServices need to be clear
  at the outset which individuals they intend to
  provide interventions for
• (Department of Health Mental Health Policy
  Implementation Guide May 2002)

7
Definitions continued

• Co-morbidity (Dual Diagnosis) is the
  co-occurrence of severe mental health problems
  (and personality disorder) which are caused or
  complicated by problematic consumption of illicit
  substances, misuse of prescribed drugs or
  alcohol.
• (Nottingham Dual Diagnosis Team)

8
Definitions continued

• The term Dual Diagnosis is not helpful in
  describing this group. First the term is
  non-specific and could refer to a whole range of
  problems.
• Secondly low levels of substance misuse
• (i.e. not enough to merit a diagnosis of
  dependence or abuse)
• can have a significant effect on those
  individuals with severe mental health problems
  and therefore does not warrant the label
  diagnosis.
• (Graham H et al 2003)

9
Severe Mental Illness

• The DoH sets out 5 defining characteristics
• They are diagnosed (typically with Schizophrenia
  or Bipolar affective disorder).
• Are substantially disabled due to their illness.
• They are currently displaying florid symptoms as
  part of an enduring condition.
• Have suffered recurring crises resulting in
  admissions or interventions.
• They may at times pose a significant risk to
  themselves or others.

10
DoH definition examples
Severity of substance misuse
HIGH
E.g. A man who drinks 2.5 litres of cider per day
and experiences increasing anxiety
E.g. A 22 year old man who has a diagnosis of
bi-polar disorder who binge drinks and has
started experimenting with intravenous drug
taking.
HIGH
LOW
Severity of mental health problem
E.g. A woman with schizophrenia who smokes 2-3
joints daily to compensate for social isolation
E.g. a young woman who takes ecstacy at the
weekend and who is now experiencing depression
throughout the week
LOW
11
Service Models of joint mental health and
addiction services

• Consecutive-dangers slip between services
• Addiction services deal with mild/moderate mental
  illness mainly affective disorder
• Parallel-dangers of sub-optimal treatment
• Dedicated DD-not cost-effective deskills
• Integrated-DOH recommendation
• Low priority with gate-keeping for both services

12
Prevalence in the UK

• An inner London Study showed that 36 of people
  with a psychosis had abused substances. (Tyrer et
  al 1999).
• A recent study conducted in 2 London Boroughs,
  Nottingham and Sheffield showed that prevalence
  of drug taking in people with mental health
  problems had risen to 44. (Weaver et al 2003)

13
Client Profile

• Male (80)
• Between the age of 23 35.
• Poly-drug user. (55)
• Engaged in experimental opportunistic drug
  taking.
• High levels of risk
• (40 inject,
• violence or suicide)

14
In homeless population

• Higher rates of Substance Misuse
• Higher rates of SEMI
• Higher rates of DD
• Increased risk of sharing injecting equipment
• Increased risk of unsafe sexual practices as in
  all DD

15
The drugs that they take

• 49 take stimulants (amphetamines and cocaine).
• Crack smoking is sharply on the increase.
• 27 take heroin.
• 37 smoke cannabis and drink heavily.
• 40 inject the drugs they take often straight
  away and in high risk sites.

16
Vulnerability to Alcohol Misuse

• Most commonly available and often cheapest drug
• More vulnerability in
• Bipolar and affective disorders
• non-compliant, socially isolated

17
Increased dose recruits additional monoamines

• Dose Low

18
Cannabinoids neurobiology

• CB1 receptors widely distributed in cortex
• Endogenous cannabinoids (eg anandamide)
• ?9 THC releases dopamine from nucleus accumbens
  and prefrontal cortex
• Inhibits GABA glutamate transmission

19
Brainstorm.

• Why might people with severe mental health
  problems take drugs or alcohol ?

20
Psychosis is lonely in adolescent development

• Substance misuse aetiology as for general
  population-fun,escape, relaxation, environmental
  access
• providing an accepting social in group initially
  and delays effective early intervention
• Neurodevelopment in brain regions associated with
  learning for adult roles motivation,impulsivity
  also confer addiction learning (Chambers RA, AM J
  Psych 2003 1601041-1052)

21
?Already primed dopamine reward circuits

• E.g.70 cf 25 smoke before first symptoms of
  mental illness
• ?common aspects to both conditions of dopamine
  circuits dysfunction.
• Volkov ND. Cereb Cortex 200010318-325

22
Pills DD want

• Development of severe mental illness and
  substance misuse at key stage of teenage
  autonomy leads to conflict
• Increases hostility
• Familial high expressed emotion worsens
• Further alienates support network
• Increases vulnerability to homelessness and
  coming within the CJ system

23
versus pills DD dont want

• to
• addiction treatment

• Non-compliance

24
Dual Diagnosis worsens SMI outcomes

• Increases relapse rates
• Rehospitalisation
• Increases positive symptoms of psychosis
• Worsens clinical and functional outcomes

25
Interactive work.
What are the differences between symptoms of
severe mental health problems and symptoms
relating to drug taking? Clue ICD
26
Psychosis during cannabis intoxication

• Surveys of cannabis users
• ? 15 report experiencing brief psychotic
  symptoms (paranoid beliefs / hearing voices)
• Experimental studies of intravenous THC (DeSouza
  2004)
• 22 subjects, randomly given IV THC or placebo
• Highly significant increases in psychotic symptom
  scores
• Completely resolved within 3 hours, and no effect
  up to 6 months

27
Cannabis and psychosis
cannabis use
delusions, hallucinations thought disorder
during cannabis intoxication
acute transient psychotic disorder
psychotic symptoms not due to direct
biological effects of exogenous cannabinoids
schizophrenia
other chronic psychoses
time
28
Cannabis and psychosis persisting beyond
intoxication effects

• Cannabis-induced psychosis Numerous case
  reports
• Typically described as onset of psychotic illness
  following cannabis use, and resolving usually
  within 1-2 weeks
• Observe acute transient psychotic illness
• Assumptive role of cannabis in aetiology.but 10
  of young adult population use cannabis regularly

29
Brief Assessment of Clients With Substance Misuse
Problems.
30
Three main areas of assessment

• Detection and Screening.
• In depth assessment.
• Risk assessment.

31
Dual diagnosis MHPIG states

• Since substance misuse among those with mental
  health problems is usual rather than exceptional
  and results in poorer treatment outcomes, it is
  necessary to consider its presence in all
  assessments undertaken by mental health services
• But St Georges School of medicine in London
  recently found that 26 of clients who reported
  substance misuse in their survey had not been
  assessed by acute in-patient staff as having a
  drug or alcohol problem.

32
What have I got to lose except my

• Values
• Experience
• Taboos
• Fears
• Prejudices
• For a Motivational approach

33
Detection and Screening.

• SuMMBAT (Substance Misuse Mental health Brief
  Assessment Tool).
• Self report.
• Laboratory tests (including urine, hair blood
  screening).
• Other forms of screening (Micro-lines saliva
  swabs).
• Records and other collected data.

34
Why Screen?

• It gives an accurate snap shot of drugs taken.
• Can help establish if the pattern of drug taking
  is linked to changes in MH.
• A collection of samples over time give a clear
  indication of their pattern of drug taking.
• Regular screening can act as a point to reinforce
  their motivation.
• Clients may not be aware or clear of what they
  have taken.
• If used in a non punitive way it can become an
  objective and therapeutic intervention.
• It helps us study mood, behaviours and symptoms
  and reflect these to the client.

35
SuMMBAT
36
SuMMBAT guidelines

• Which substances do they take?
• Does the client know?
• Consider other substances e.g. Px, volatile
  substances mushrooms
• How much do they spend?
• A general indication of level of consumption.
• Do they inject/smoke etc?
• Which area of the body do they inject into?
• Where do they get their works?
• Do they inject with anything in particular? (e.g.
  lemon juice)

37
SuMMBAT guidelines

• How often?
• Indicates the main pattern of drug taking e.g
  regular or binge.
• How long for?
• Indicates the impact that drug use may have had
  on M.H.Ps lifestyle.
• Level of tolerance

38
SuMMBAT guidelines contd

• What is their MH diagnosis?
• Highlights why a client may be using a given
  substance.
• Is it directly related to their drug of choice?
• What are the positive effects?
• Self-medication for illness or Px medication.
• Social inclusion.
• Coping mechanisms.
• Lifestyle.

39

• What are the negative effects?
• Physical mental health
• Finances
• Social effect
• Accommodation
• Work or activity
• Offending.
• Degree of motivation
• Asking the client what they want to achieve.
• Control or Abstinence?
• Even if motivation is low then some interventions
  are still indicated.

40
SuMMBAT Guidelines Contd

• What help does the person want?
• Education/information.
• Harm-minimisation.
• Detox.
• Abstinence.
• Relapse prevention.
• Any previous treatment?
• Useful to ascertain if they have engaged well,
  previous detoxes that worked/failed, notable
  withdrawal experiences and periods of
  control/abstinence.

41
Assessment

• Accurate assessment is fundamental to the
  effective management of people with a dual
  diagnosis.
• The aim of an assessment is to give the
  practitioner a clear picture of what is going on
  for that person and what is contributing to their
  distress
• (RCP Research Unit, 2002. Co-existing problems
• of mental disorder and substance misuse
• (dual diagnosis) an information manual.)

42
Specialist Assessment.

• Specialist assessments are undertaken to
  determine the nature and severity of substance
  misuse and mental health problems, and to
  identify corresponding need.
• The more comprehensive and focussed the
  assessment
• the better the understanding will be of the
  relationship between the two disorders.

43
Risk Assessment

• Routine risk assessment protocols need to
  address specific factors for individuals with a
  dual diagnosis.
• The severity of substance misuse, including the
  combination of substances used, is related to the
  risk of overdose and suicide.
• Exploration of the possible association between
  substance misuse and increased risk of aggressive
  or anti-social behaviour
• forms an integral part of the risk assessment,
  and should be explicitly documented if present.
  (DoH Dual Diagnosis MHPIG, 2002).

44
Risk Assessment contd

• Other aspects to consider include
• Risk to the client and others due to drug taking
  paraphernalia. E.g. the potential for needle
  stick injuries as a result of improperly
  discarded needles and syringes.
• Risk due to blood borne infections. E.g.
  Hepatitis and HIV.
• Risk due to overdose i.e. accidental overdose of
  illicit substances.

45
Risk Assessment contd

• Risk of abuse by others. E.g. clients can be
  dis-empowered or abused by drug pushers who prey
  on them for money or drug users needing a place
  to SCORE.
• Risk due to violence. Research has shown that
  this client group is more likely to be
  unpredictable, aggressive and violent. There is a
  potential risk to staff due to some of the
  individuals that a client with a co-morbidity may
  mix with.
• Risk of relapse as a direct result of their drug
  or alcohol problem

46
Harm reduction CHALLENGES traditional values

• Reducing blood borne viral transmission
• Reducing quantities of alcohol drunk/drugs used

47
Recovery Approach in Co-morbidity

• Goal Hierarchy towards
• abstinence
• Personal values
• meaning for life goals
• Risk management joint
• approach with clients and
• psychiatric substance misuse
• services

Opportunity Control Hope
48
Other questions you might ask

• What do they know/understand about the substance
  and its effects?
• What effects do they get from their psychiatric
  medication?
• What are their social circumstances?
• What have they done in the past to help control
  or abstain from drug of choice?

49
Case Study

• Adam is a 34 year old man who has a diagnosis of
  paranoid schizophrenia. Until recently he lived
  at home with his mum and step father. He now
  lives in a flat in Newtown after being thrown out
  For getting lairy his mum tells you.
• Adam injects around 1 gramme of amphetamines 4
  days per week. He also takes heroin which he
  injects intramuscularly, cocaine which he also
  injects and occasionally smokes crack. In the
  past he has drunk heavily and also taken
  steroids.
• Discuss how you would assess Adams needs, what
  issues you might prioritise and what you would do
  to try to ensure he receives a comprehensive
  service.

50
Stages of treatment

• Assessment.
• Engagement
• Building a therapeutic relationship.
• Doesnt necessarily tackle drug and alcohol
  issues immediately.
• Early empowerment
• Gives the client relevant verbal and written
  information that they may not have had before.

51
Stages of treatment contd

• Late empowerment.
• Helps the client to self monitor using drug/drink
  diaries.
• Simple monitoring.
• Goal setting.
• Action/Active phase.
• Active detoxification/control of substance taking
  (based on goals set).
• Controlled drinking groups.
• Relapse prevention including a relapse prevention
  plan.

52
Engagement and risks

• UK Mental Health Services
• AOT
• Early Intervention Services
• Substance Misuse can present in crisis but would
  normally be excluded from Crisis Team assessment
• Dual diagnosis integrated model with MH Services
  lead for severe enduring MI due to limited
  evidence for dedicated service

53

• Psychosocial interventions are the evidenced
  treatments to improve outcomes not substitute
  medication for stimulant/cannabis abuse
• No evidence of improved outcome by matching
  METCBTsocial Network Therapy12 step for
  alcohol
• (1997 Project Match)
• Community reinforcement programmes- eclectic,
  intensive,repeatedly available to engage,
  aftercare
• is evidenced

54
?
55
1936 Mythology2006 Limited Evidence
56
1936
One moment of bliss, a lifetime of regret ....
57
2004.

• We and about five other studies have shown that
  if you start taking cannabis early and heavily
  you are about seven times more likely to develop
  schizophrenia
• BBC news 22nd Jan 2004
• Prohibitionists love to claim cannabis causes
  schizophrenia. Mostly because all their other
  claims have been proved wrong. Just like this one
  will soon be.
• The Hempire Aug 2004

58
ACMD

• Advisory Council on the Misuse of Drugs
• Independent expert body
• Remit to review drug situation and advise
  Government on prevention / dealing with social
  problems
• Decision to downgrade based on ACMD report March
  2002
• Request by Home Secretary in March 2005 to review
  evidence
• Department of Health funded Systematic Review of
  evidence that cannabis use increases risk of
  psychotic and affective disorders (June
  2005-June 2006)

59
Cannabis and schizophrenia

• Cross-sectional studies show that cannabis use in
  people with schizophrenia is more common than in
  general population
• Limitation of cross-sectional studies
• Cannabis increases risk of schizophrenia?
• Schizophrenia increases likelihood of using
  cannabis?
• (self-medication or reverse causation effect)

60
Longitudinal or cohort studies
time
cohort
cannabis
no cannabis
61
Systematic review of cannabis use and risk of
developing psychoses

• What is the evidence that cannabis use increases
  risk of developing schizophrenia?
• What is the evidence that cannabis use increases
  risk of developing other psychoses?
• What is the evidence that cannabis use in people
  with schizophrenia results in a poorer long-term
  outcome?

62
Systematic review of cannabis use and risk of
developing psychoses

• Longitudinal (cohort) studies
• Reverse causation excluded?
• Intoxication effects excluded?
• Confounding assessed?

cannabis use
schizophrenia
personality traits
63
Systematic review of cannabis use and risk of
developing schizophrenia and other psychoses

• Department of Health funded
• Glyn Lewis
• Tess Moore
• Anne Lingford-Hughes
• Peter Jones
• Tom Barnes

64
Search strategy databases

• Medline, EMBASE, CINAHL, PsycINFO, ISI Web of
  Knowledge, ZETOC, BIOSIS, LILACS, MEDCARIB,
  National Research Register
• Contacting experts Louise Arsenault IOP,
  Bovasso, Michael Davidson, Mark Weiser
  NY/Israel, Louise Degenhardt, William Eaton NY,
  Robert Ferdinand, David Fergusson (Christchurch),
  John MacLeod, Robin Murray, George Patton
  Melbourne, Richie Poulton Dunedin, David Semple,
  Jim van Os Maastrict, Helene Verdoux Bordeaux

65
Review flow chart
Total hits 6718 (Duplicates 2684) Reference lists
expert knowledge and other databases 47  Total
N4037
Titles and abstracts which were very unlikely to
be relevant, excluded n 3868
Titles and abstracts possibly relevant N 169
Papers not relevant (full papers or
abstract) n139
Papers included Psychosis n9 (6 studies) Papers
included Depression n19
66
Summary of studies included
N in cohort Length of follow-up N with psychotic outcome Psychosis type Effect of cannabis on risk
Swedish conscripts (Andreasson 1987) (Zammit 2002) 50,087 27 years 362 (0.7) schizophrenia ?
Dunedin (Aresenault 2002) 759 11 years a) 190 (25) b) 25 (3.3) a) psychotic symptom b) schizophreniform ? ?
NEMESIS (van Os 2002) 4045 3 years a) 38 (1) b) 10 (0.25) a) mild symptom b) moderate symptom ? ?
EDSP (Henquet 2005) 2437 4 years a) 424 (17) b) 174 (7) a) psychotic symptom b) ? 2 symptoms ? ?
Christchurch (Fergusson 2005) 1055 2-7 years N/A psychotic symptom ?
ECA (Tien 1990) 4994 1 year 507 (11) psychotic symptom ?
67
Odds ratio The ratio of the probability of
having a disease in a population exposed to a
certain risk factor (e.g. cannabis use) and the
probability of having the same disease in a
population not exposed.
68
weight statistically adjusted to take account
of actual or potential confounding factors.
69
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70
What factors might have lead to studies
over-estimating the true association between
cannabis use and psychosis?
71
Reverse causation
well
psychosis
cannabis use
sub-clinical symptoms
prodrome
72
Confounding
well
psychosis
cannabis use
personality traits, other drugs
73
Bias intoxication effects
well
psychosis
cannabis use
continued cannabis use leads to intoxication
symptoms (regular users)
74
Quality assessment of studies included
Reverse causation excluded Intoxication effects excluded Number of confounders ( change from crude)
Swedish conscripts (Andreasson 1987) (Zammit 2002) 11 (30 ?)
Dunedin (Aresenault 2002) - 4 (no crude results)
NEMESIS (van Os 2002) 6 (35 ?)
EDSP (Henquet 2005) - 9 (15 ?)
Christchurch (Fergusson 2005) - 17 (30 ?)
ECA (Tien 1990) 5 (15 ?)
75
What factors might have lead to studies
under-estimating the true association between
cannabis use and psychosis?
76
Bias attrition
well
psychosis
cannabis use
attrition greater in cannabis users who become
ill?
77
Bias random misclassification
well
psychosis
cannabis use
change in cannabis use over time
cannabis dose measured inaccurately
78
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79
Sensitive periods of risk?

• Cerebral development incomplete until late teens
• (myelination, synaptogensis..)
• Any evidence for greater risk if use cannabis
  during early adolescence compared to adulthood?

80
Age at first use of cannabis

• Dunedin
• Age 15 (symptoms) 6.6 (4.8, 8.3)
• Age 18 (symptoms) risk difference 1.0 (0.3,
  1.8)
• Age 15 (schizophreniform) OR 3.1 (0.7, 13.3)
• Age 18 (schizophreniform) OR 1.4 (0.5, 3.7)
• Swedish conscripts
• Age 15 (schizophrenia) OR 1.2 (1.0, 1.4)
• Age 18 (schizophrenia) OR 1.2 (1.1, 1.4)
• Multiple logistic regression analyses showed
  cannabis use by 15 years 18 years had more
  schizophrenia symptoms than controls at age 26yrs
• Cannabis by 15 yrs more than 4 times as likely to
  have schizophreniform disorder at 26 years than
  controls.

Risk Difference is the risk in the treated group
minus the risk in the control group ...
Risk Difference is the risk in the treated group
minus the risk in the control group ...
Risk Difference is the risk in the treated group
minus the risk in the control group ...
Risk Difference is the risk in the treated group
minus the risk in the control group ...
Risk Difference is the risk in the treated group
minus the risk in the control group ...
Risk Difference is the risk in the treated group
minus the risk in the control group ...
Risk Difference is the risk in the treated group
minus the risk in the control group ...
Risk Difference is the risk in the treated group
minus the risk in the control group ...
81
Age at first use of cannabis

• Risk Difference
• risk in the treated group minus the risk in the
  control group (confidence intervals).If an
  experimental intervention has an identical effect
  to the control, the risk difference will be 0. If
  it reduces risk, the risk difference will be less
  than 0 if it increases risk, the risk difference
  will be bigger than 0.

Risk Difference is the risk in the treated group
minus the risk in the control group ...
Risk Difference is the risk in the treated group
minus the risk in the control group ...
Risk Difference is the risk in the treated group
minus the risk in the control group ...
Risk Difference is the risk in the treated group
minus the risk in the control group ...
Risk Difference is the risk in the treated group
minus the risk in the control group ...
Risk Difference is the risk in the treated group
minus the risk in the control group ...
Risk Difference is the risk in the treated group
minus the risk in the control group ...
Risk Difference is the risk in the treated group
minus the risk in the control group ...
82
Summary of findings relevant to clinical practice

• Only one longitudinal study that examines effect
  of cannabis use on risk of schizophrenia
• Two studies examine other similar outcomes
• Dunedin cohort 3.5 schizophreniform disorder in
  1 year
• (200x more than expected 0.015 schizophrenia)
• NEMESIS needs-based diagnosis most severe
  symptoms (0.2 in 3 years)

83
Summary of findings relevant to clinical practice

• Reverse causation unlikely given study designs
• Confounding
• Associations all reduced by 15-40 after
  adjustment
• Associations persisted after adjustment
• Residual confounding possible
• Intoxication
• Unlikely given assessment tools
• However, how do you exclude this in regular
  users?

84
Support for causality

• Consistency of results
• Increased risk of psychoses in all these studies
• Not adequately explained by bias, confounding or
  reverse causation
• Dose-response effect in all studies that examined
  this
• Compatible with other sources of knowledge
• Cannabis intoxication psychosis
• Neurobiology of cannabinoids abnormalities in
  schizophrenia
• There is always room for doubt.

85
Unanswered questions

• What effect does regular use of cannabis over
  many years have?
• What about exposure during early teenage years?
• What about use of higher potency forms of
  cannabis?
• What about risk in those already vulnerable, eg
  family history?
• Any other groups where cannabis use may be
  particularly harmful?
• eg Catechol-O-Methyl Transferase genotype
  regulates dopamine metabolism (Caspi et al 2004)
• What about time trends?

86
Are future studies likely to help?

• Schizophrenia incidence approximately
  15/100,000/year
• Cohort study of 10,000 people, followed up for 20
  years age 12-32
• Probably about 30 people with schizophrenia
• More reasonable to study endophenotypes of
  schizophrenia
• eg specific neuropsychological deficits
• Animal models of endophenotypes may be particular
  helpful
• Definitive answer not likely in decades to come

87
What if someone already has schizophrenia?

• Part of current systematic review not complete
  as yet
• Clinical experience and evidence from a number of
  studies suggest that cannabis use
• Increases relapse rates
• Increases positive symptoms of psychosis
• Is associated with reduced compliance with
  medication
• Worsens clinical and functional outcomes
• Strength of evidence regarding this unclear
• Future studies feasible, as well as intervention
  trials for reducing cannabis use in people with
  schizophrenia

88
Public health perspective

• Does cannabis cause psychotic illnesses?
• or..
• Would reducing cannabis use reduce the
  incidence of psychotic illnesses?
• Assuming the strength of association from studies
  above are correctly estimated and that cannabis
  use is truly causal...
• Approximately 10-20 of psychosis outcomes in
  these studies would not have occurred if no-one
  used cannabis

89
Individual perspective

• Individual lifetime risk of schizophrenia is 0.7
• If using cannabis daily increases risk by 2.5
  times
• Lifetime risk of schizophrenia 0.7 x 2.5 2
• Individual risk relatively low, but may be much
  higher if heavy or frequent use, if use more
  potent forms, or use at an early age
• Furthermore, it may be the only modifiable risk
  factor there is at present

90
Clinical perspective

• If someone has experienced any psychotic-like
  phenomena following use of cannabis should be
  strongly advised about possible risk of
  developing a severe psychotic illness
• If a patient has a psychotic illness, they should
  be routinely strongly advised (including written
  information) that using cannabis may make this
  worse
• We should actively target family members of
  patients with schizophrenia to advise about
  possible risk if use cannabis

91
Clinical perspective

• Message to public
• The evidence supports the view that using
  cannabis can increase risk of developing a
  psychotic illness, including chronic and severe
  psychotic illnesses such as schizophrenia
• Reference
• ACMD Further consideration of the classificatioof
  cannabis under the Misuse of Drugs Act 1971,
  HMSO,2006