Reducing the Harms of Cannabis Use: The Policy Debate in Australia

1. Reducing the Harms of Cannabis Use: The Policy Debate in Australia Wayne Hall National Drug and Alcohol Research Centre

2. Outline • Analysis of harms caused by cannabis use • to cannabis users and others • Analysis of harms arising from prohibition • to cannabis users and others • using Australian data • Proposals for reducing both sets of harms • under discussion in Australia • Some tentative policy prophecies

3. Cannabis use among Australian males, 1998 NDS Survey

4. Cannabis use among Australian females, 1998 NDS Survey

5. Difficulties in Assessing the Adverse Health Effects of Cannabis Use • Limited evidence base • rigour vs relevance of animal studies • paucity of epidemiological research • problems in causal inference • other drug use • user characteristics • Social context of the evaluation • polarised views • problem deflation and inflation

6. Acute Health Effects • anxiety, dysphoria, panic, paranoia • especially among naive users • cognitive and psychomotor impairment while intoxicated • psychotic symptoms (probably rare) • high doses of THC • vulnerability

7. Accidental Injury • Impaired performance on complex tasks • Reduced risk taking • aware of impairment • Simulated driving impaired • Epidemiological evidence unclear • measurement of impairment • confounding with alcohol

8. Health Effects of Chronic Use • Respiratory disease • Dependence • Effects of Maternal cannabis use • Effects on adolescent development • Schizophrenia & psychosis • Issue of increased THC content

9. Respiratory Effects • Cannabis primarily smoked • Cannabis smoke similar to tobacco smoke • Tobacco smoking causes • obstructive respiratory disease • respiratory infections • lung cancer • Most also smoke tobacco

10. Evidence • Increased cough, sputum, wheeze • Histopathological changes • most marked in MT • at an earlier age • Impaired immunological responses • pulmonary alveolar macrophages • Increased health service use • Decreased respiratory function ?

11. Respiratory Cancers • Cause for concern • composition of cannabis smoke • histopathological changes • case series of cancers in young adults • evidence of mutational changes in lung tissue • Case-control studies a priority

12. Public Health Impact of Respiratory Risks • small by comparison with tobacco • in public health terms • not in terms of personal risk • a consequence of smoking as a route • encouraging non-smoking use? • most smoke tobacco anyway • amplification of respiratory risks

13. Significance of a Dependence Syndrome • Thought to have a low dependence potential • apparent absence of a withdrawal syndrome • Important for informed choice by users • users need to be aware of the risk • Increases exposure to health risks • by increasing duration of use

14. Evidence • Users seeking help to stop • Australia, Sweden, & USA • Epidemiological studies • ECA 4% population lifetime • NCS 4% population lifetime • NSMWHB 2% of population past year

15. Tolerance and withdrawal • tolerance in animal & human studies • withdrawal syndrome in animals • elicited by cannabinoid antagonist • withdrawal symptoms in human laboratory studies: • irritability, anxiety, insomnia, depression • these common in clinical populations

16. Clinical features • a withdrawal syndrome common in users seeking help • compulsive use patterns • also common in problem users • perceived to be a problem? • by a minority who meet criteria in community • as for alcohol & other drugs

17. Risks and Consequences • Risks • 9% of lifetime users (NCS study) • 33-50% of daily users • Consequences? • respiratory symptoms • impaired memory • poor work performance • social disapproval

18. Need for Treatment • Fewer than 10% seek any treatment • Why so few? • high rates of remission? • fewer consequences? • existing treatment services unattractive? • How treatable? • self-help • brief interventions • psychotherapy

19. Adolescent Development • Concerns • educational performance • progression to “harder” drugs • Issues • rarity of heavy use • causal attribution • other drug use • user characteristics

20. Natural history of cannabis useunder prohibition • initiation in mid teens • most use intermittent • relatively low capture rate for daily use • discontinue mid to late 20s • impact of marriage, mortgages & children • persistent use relatively rare • predicted by early initiation • heavier use

21. Current monthly use of various drugs by age (Chen & Kandel, 1995)

22. Educational Performance • Cross sectional studies • Longitudinal studies US & NZ • selective recruitment to use • peer influence • small direct contribution • Educational implications • exculpation & blame • school policies

23. A Gateway Drug? • Cross-sectional & longitudinal studies • Sequence of drug involvement • alcohol & tobacco precede • cannabis which precedes • heroin & other drugs • < 5% of cannabis users use “harder” drugs • Progression predicted by: • earlier initiation & heavier use

24. Explanations • selective recruitment to use • at risk & troubled youth more likely to use • peer networks • regular users affiliate with peers who use • peer culture supportive of drug use & crime • drug markets • provide opportunities to use other illicit drugs • genetic vulnerability to drug dependence

25. Cannabis & Psychosis • “Cannabis psychosis” • toxic psychosis • functional psychosis • Cannabis as a risk factor for schizophrenia • precipitation • exacerbation

26. Potential significance • High prevalence of cannabis use • especially at period of risk for psychosis • complicates causal attribution • Additional cases of psychosis • Exacerbation of psychosis • Suffering of affected persons & families • Costs of treating psychoses

27. “Cannabis Psychoses” • Conflicting opinions • clinical observations • limited case-control evidence • Probably exist but rare • either require large doses of THC • or vulnerability • Ethically difficult to reduce uncertainty

28. Cannabis & Schizophrenia • Cannabis & schizophrenia associated • in general & clinical populations • Cannabis use probably exacerbates disorder • reasonable prospective evidence • Possibly precipitates disorder in vulnerable • Swedish conscript study • Less likely to cause disorder de novo • no evidence of rising prevalence

29. The Issue of Potency • Claim THC content of cannabis x 30 times • Absence of good data: • testing not required • or done regularly • Media publicity to unusual cases • biased sampling • Changes in patterns of use • earlier initiation • heavier use of more potent forms

30. THC content of Marijuana 1980-98: US Potency Monitoring Project

31. Changing Patterns of Cannabis Use • Most users smoke “heads”and use bongs • Weekly+ use accounts 96% of market • Earlier initiation of use: • more regular use by younger users • more problem users? • More use among vulnerable groups • persons with schizophrenia • conduct disordered adolescents • More obvious problem users

32. Possible Effects of Increased Potency • For naive users: • higher risk of dysphoric & psychotic symptoms • higher rates of discontinuation? • higher rates of accidental injury? • For regular users: • lower respiratory risk, if users titrate dose • higher risk of dependence? • especially among adolescents • more cognitive impairment?

33. Summary: adverse health effects • Dependence • 10% chance for users • 33-50% for daily users • consequences? • Respiratory disease • chronic bronchitis • cancer? • Motor vehicle accident risk?

34. Risks of Chronic Use • Adolescent use • selective recruitment to use • peer influences • indicator of at risk status • Psychosis • probably produces symptoms • probably exacerbates and possibly precipitates schizophrenia in vulnerable

35. Overall Assessment • On current patterns of use • small to moderate public health impact • less than alcohol & tobacco • with possible exception of MVA, harms caused to users • Do these adverse effects justify prohibition? • Would relaxing prohibition increase: • rates and duration of regular cannabis use? • rates of problems related to cannabis use?

36. Putative Harms Caused by Cannabis Prohibition • Loss of individual liberty to use cannabis • A large scale cannabis blackmarket • controlled by criminals • unregulated and no quality control • untaxed by government • corruption of public officials • Arms race in policing technology • helicopters and satellite surveillance • indoor hydroponic cultivation

37. The Harms of Prohibition:Effects on Rule of Law • Discriminatory non-enforcement of law • only 1-2% of past year users are prosecuted • more often lower SES, unemployed males • Brings law into disrepute among the young • Effects on users of conviction • stigma of criminal record • no impact on cannabis use • disproportionate penalty for self-harm

38. The Harms of Prohibition:Inefficient Uses of Scarce Resources • Paradox of cannabis law enforcement • most cannabis use goes undetected but • majority of drug offences are for cannabis use • Inefficient use of scarce resources: • police and Criminal Justice System • Loss of medical uses of cannabis products • e.g. anti-nausea agent & appetite stimulant • analgesic and antispasmodic

39. Options for Reducing Cannabis-related harms • Intensified enforcement of prohibition • US and Swedish models • Legalisation of cannabis use • de facto e.g. the Netherlands • or de jure • “Decriminalisation”: • prohibition with civil penalties • diversion into treatment or education

40. Intensification of Prohibition • American model • substantial fines and gaol sentences • workplace drug testing • school education & mass media campaigns • “zero tolerance” and strong social disapproval • Swedish model • disapproval similar to US • compulsory treatment rather than imprisonment

41. Problems with Intensified Enforcement • Costs of implementation • imprisonment or compulsory treatment • expanding role of government vs general retreat • Presupposes societal consensus • absent in Australia where opinion divided • Limits to effectiveness • may have decreased use in USA but rising again • may be easier to keep low as in Sweden • Backlash against prohibition? • excessive zeal in enforcement favours reformists

42. Cannabis Legalisation • a minority option in Australia (25%) • credibility of opponents and proponents • an irreversible step • likely to increase heavy & regular use • experience with alcohol & other drugs • contrary to international treaties • and international sentiment

43. A cautious step easily reversed Reduces harms to users discriminatory enforcement Better use of scarce resources Minimal impact on use Little or no effect on blackmarket Inconsistent: use not a crime but sale is Symbolism implies cannabis use is safe & acceptable Decriminalisation Pros Cons

44. A Choice of Evils • Insufficient data for utilitarian analysis • Trading off incommensurable values: • users’ health • social disorder and crime • civil liberties • A task for the political system • polarisation of public opinion • lack of consensus on trade-off • minimal changes to status quo most likely

45. Reduced Penalties for Personal Use • Removal gaol penalties for 1st offenders • de jure recognition of practice • Cautioning and diversion as an alternative • may increase number of users dealt with • a proportionate response to self-harm

46. Reduced Penalties for Personal Use • Reduce push for more radical reform • more reversible policy • consistent with international agreements • Coupled with penalties for use when driving • to address most probable adverse effect on non-users • Graduated penalties based on THC content?

47. A Necessary Breathing Space? • Epidemiological research on adverse effects • on adolescent development • serious long term health consequences • cancers, respiratory disease, psychosis • More credible health education • scepticism about scares among young • parallels with the effects of alcohol & tobacco: • respiratory risks, MVA, dependence, psychosis • Better assessment of therapeutic uses • AIDS& cancer related nausea and wasting • neurological diseases and intractable pain