Reefer Madness: Moral panics and science

1. Reefer Madness:Moral panics and science Rob Poole

3. the research suggests an increased risk of psychosis, and the growing consensus is that this is not just because users are more troubled to start off with.� The Guardian, 29th October 2007.

4. Moral panics

6. Similar events, different times

13. Daily Mirror 14/11/08 Jersey children's home probe: Top cop suspended as investigation collapses By Don Mackay 13/11/2008 Top cop suspended in probe storm The probe into the Jersey children's home collapsed yesterday when police said there was no evidence of murder or torture.

14. My values in this debate Cannabis is an unpleasant drug with a wide range of adverse effects No matter what we do, cannabis is not going to go away, and we have to learn to work with its adverse effects Science and intellectual rigour matter We can have an positive or negative effect on public debate

15. Drug Induced PsychosisPoole and Brabbins 1996 Intoxication mimicking functional psychosis Pathoplastic reactions Chronic hallucinosis Drug induced relapse Withdrawal states Clouding of consciousness Depressive crash Panic attacks True drug induced psychosis Risk factor (Andreasson, 1987)

16. Cannabinoids

17. ?-9 tetrahydrocannabinol (THC)

18. Cannabidiol

19. A few myths Drug use is ever increasing Cannabis is up to x8 to x30 strength of the stuff we used to smoke in the 1970s Stronger cannabis leads to heavier intoxication Cannabis is non-addictive But�.. It is a lot cheaper and is locally produced

20. Does cannabis exacerbate psychosis? About 15% of people with schizophrenia misuse drugs. About 30% misuse alcohol. More ill or just ill and stoned? Associated with more frequent relapse but many confounders. Not a good thing.

21. Why do people with mental illness smoke cannabis? It�s fun It�s something to do It structures the day Drug using sub cultures are tolerant of deviant behaviour It�s a �normal� place for stigmatised people to hang out It�s a loser�s game

22. Alcohol and schizophrenia Number of data based papers 1995-2005: None Unpublished data, Liverpool Homeless Team 1998-2003: Drug users did much the same as other psychotic homeless people, whether they gave up or not. Drinkers had far worse outcome (death and permanent institutionalisation).

23. Cannabis as a causal factor Andreasson, Allebeck, Engstrom and Rydberg, Lancet 1987: 15 year follow up. x6 increased risk, x2.3 if those with diagnosis excluded. Risk to very heavy users: 3%

24. Zammit, Allebeck, Andreasson, Lundberg and Lewis, BMJ 2002 50,000 subjects Linkage of government data Self report of drug use and background 27 year f/u Excluded other drug use and cannabis preceded diagnosis 362 developed schizophrenia Odds ratio 2.2, adjusted 1.5 Higher exposure led to higher risk

25. Van Os et al, Am J Epid, 2002. Dutch prospective study, 1 and 3 year follow up, 4000 subjects, plus 60 with psychosis. Users at baseline x3 rate of psychotic symptoms at follow up. Most of the effect due to big effect on those with symptoms at baseline. Baseline use had more effect than later use.

26. Arsenault, Cannon, Poulton, Murray, Caspi, Moffitt, BMJ 2002 Dunedin birth cohort. 1037 people born 1972-73 Heavy use at 15 and 18 years associated with increased risk of Sz by age 26. Risk higher the earlier the use but not all findings statistically significant when controlled for prodromal symptoms. Low numbers: 3/29 early users developed Sz versus 22/730 non-users.

27. Cannabis as a causal factor Definite association between early heavy cannabis use and later schizophrenia. Not due to other drugs. Not due to self medication. Not a toxic effect of cannabis. How sure can we be that confounders have been fully factored out?

28. Best guess on size of risk �Cannabis use and risk of psychotic or affective health outcomes: a systematic review� Lancet 2007 Moore, Zammit, Lingford Hughes, Barnes, Jones, Burke, Lewis.

29. Summary of risk

30. Biological Psychiatry, 2005 Caspi, Moffitt, Cannon, McClay, Murray, Harrington, Taylor, Arsenault, Williams, Braithwaite, Poulton, Craig �Moderation of the effect of adolescent-onset cannabis use on adult psychosis by a functional polymorphism in the Catechol-O-Methyltransferase gene: Longditudinal evidence of a Gene X Environment Interaction�

31. Dunedin birth cohort again Obtained DNA samples from the entire cohort. Reanalysed previous data with genetic data The combination of one version of gene (Val/Val genotype) and cannabis use accounted for most or all of the increased risk of schizophrenia for users.

32. COMT Three polymorphisms, Val/Val, Val/Meth, Meth/Meth. Different levels of biological activity (Val/Val most active). Right neurotransmitters and locations. Coded on chromosome 22. Long regarded as a candidate gene.

33. COMT But�.. A lesion in search of a disorder: affective disorder, schizophrenia, ADHD, leimyoma, etc. Low statistical power Long history of non-replication and withdrawal of such findings

34. Discussion with researchers 2005 Deprivation, maladjustment and marginalisation associated with both early substance misuse and schizophrenia. What about cigarette smoking? Alcohol? Truancy? Where�s the epidemic? How much evidence do you need? What about the null hypothesis? �Doesn�t contribute to the debate.�

35. BJPsych 2007 Zammit et al. �Genotype effects of CHRNA7, CNR1 and COMT in schizophrenia: interactions with tobacco and cannabis use� 750 with Sz, 688 controls, smaller group with Sz used to study cannabis effect (493). No effect from any of these, including COMT and cannabis use.

36. Other COMT studies Can not exclude a role for COMT in Sz, but if so, its not straight forward Val/Val COMT plus cannabis equals later schizophrenia seems not to stand up.

37. The public debate Mostly conducted around interviews with respectable researchers but� Misinformation Crusades Conflation of dangers and control measures The corruption of a generation of children

38. Article by RM, Guardian 17/9/02 Cannabis causes psychosis. This has been known for years, the evidence only now available. People with schizophrenia have a miserable life. Bright, no problems, cannabis dependency in teens led to schizophrenia. Rethink is full of parents who believe their child�s illness was caused by cannabis. Rate of Sz in South London has doubled, cannabis and cocaine could be the cause. This is why services are in a mess.

39. Guardian 3/7/03 Based on talk to RCPsych annual meeting �Very bright as a child, no obvious problems, cannabis dependence in teens, then schizophrenia�

40. Guardian 7/1/04 RM: Cannabis use is number one problem facing mental health services. 80% of new cases of schizophrenia involve cannabis. Risk is x7

41. Guardian 20/1/04 RM: Cannabis main reason for set backs during in patient stays. Most harmful to people with established psychosis and to children with prodromal features Classification irrelevant. Public should be informed. cf evidence re Smoking and cancer in the 1950s

42. BBC News 1/12/04 Marjorie Wallace of SANE: Britain is cannabis capital of Europe. Clamp down on drug dealing in play grounds and hospital wards. Cliff Prior of Rethink: Reclassification has confused people.

43. New Scientist 26/3/05 JvO: Governments should focus on keeping cannabis out of teenagers� hands. Objections to the kind of people who hang around coffee shops. Mary Cannon: �This is a large effect, similar to the size of smoking and lung cancer.�

44. Panorama BBC1 Sunday 19/6/05 RM: New type of person with schizophrenia who lacks antecedent problems other than cannabis. More patients with schizophrenia. Sz due to dopamine overactivity, and cannabis �revs up� dopamine. Frequency of Sz in South London (Brixton) has doubled since the 1960s: services are overwhelmed by the number of patients coming through, possibly because to the impact of cannabis. Once you�ve had a psychotic episode your dopamine receptors are sensitised.

45. Guardian 16/12/05 Julie Lynn-Evans: �Heroin addiction is curable, the effects of skunk are not� Modern cannabis x30 THC Uncorrected odds ratios (e.g. x6 risk) Marjorie Wallace: ��triggers a journey of life long disintegration� Role of cannabis in causing violence Trevor Turner: it�s down to confounding factors RM: Scare stories have reduced consumption It makes you paranoid (true) forgetful (true) and irritable (true)

46. Bad Science, Guardian 28/7/07 Reporting press reactions to Lancet�s systematic review. Daily Mail: One joint increases risk by 40% 175 studies (actually seven studies and 11 papers). 40% increase in a low risk. Assumption that 800 cases can be prevented by reclassification or some other enforcement measure.

47. Advisory Council on Misuse of Drugs Have tended to stick to the evidence Do not dismiss risk Have consistently advised against confusing health concerns and effective control methods Have been ignored or vilified

48. Asked to review classification in July 2007 Cannabis use is dropping Incidence of schizophrenia dropping Cannabis is stronger but people use less Risk, if it exists, is small Reclassification will criminalise users, because all users are suppliers.

49. Government reclassify anyway because Eminent experts have told Jacqui Smith about the awful effects Gordon Brown says skunk is lethal Whilst recognising the point made by ACMD are accurate, there is real public concern about the health risks

50. So�. More rhetorical heat than evidence. The debate has been affected by the reductionist biological paradigm that underlies psychiatry. Cannabis may cause schizophrenia, but there are other explanations that are equally compatible with the data. Distortions in our debate is adversely affecting public policy. What SHOULD we do with this kind of ambiguous finding?

51. Meanwhile�.. �Drug induced psychosis� is alive and well, even in Liverpool but Arendt et al, BJPsych 2005 3 year follow up of 535 Danes with �cannabis induced psychosis� 44.5% of them re-diagnosised, mainly to schizophrenia, within 3 years Similar findings in Liverpool

52. Some recommended books

55. This book is dedicated to the late Leo Fender, whose supreme mastery of the art of guitar design was unencumbered by an ability to play the instrument