What are the Policy Implications of the Evidence on Cannabis and Psychosis?

Abstract

French

Objective:

To explore the implications for mental health services, for health education about the risks of cannabis use, and for public policy toward cannabis use of observational evidence that cannabis use is a contributory cause of psychosis.

Method:

Using comparative analyses of similar evidence for the harmful effects of alcohol, tobacco, and amphetamine use, we considered the relation between observational evidence and action on cannabis. We examined arguments on the grounds of public health prudence for discouraging cannabis use by young individuals. With the assumption that the relation may be causal, we considered recommendations for policy in mental health services, health education, and public policy toward cannabis.

Results:

The observational evidence and biological plausibility of the hypothesis that cannabis is a contributory cause of psychosis is at least as strong as evidence for causal relations between heavy alcohol and amphetamine use and psychosis. On public health grounds, there is a good case for discouraging cannabis use among adolescents and young adults. It remains uncertain how best to discourage use and at whom campaigns to reduce cannabis use should be targeted.

Conclusions:

We should discourage young adults seeking treatment in mental health services from using cannabis and inform them of the probable mental health risks of cannabis use, especially of early and frequent use. We must exercise caution in liberalizing cannabis laws in ways that may increase young individuals' access to cannabis, decrease their age of first use, or increase their frequency of cannabis use. We should consider the feasibility of reducing the availability of high-potency cannabis products.

Keywords

cannabis use psychosis policy mental health services health education penalties

References

De Irala

Ruiz-Canela

Martinez-Gonzalez

. Causal relationship between cannabis use and psychotic symptoms or depression. Should we wait and see? A public health perspective. Med Sci Monit 2005;12:RA355–8.

Grotenhermen

How to prevent cannabis-induced psychological distress… in politicians. Lancet 2004;363:1568–9.

Mirken

Earleywine

The cannabis and psychosis connection questioned: A comment on Fergusson et al. Addiction 2005;100:714–5.

Zimmer

Morgan

Marijuana myths, marijuana facts. A review of the scientific evidence. New York (NY): The Lindesmith Center; 1997.

Degenhardt

Hall

Is cannabis a contributory cause of psychosis?

Can J Psychiatry 2006;9:556–65.

Arseneault

Cannon

Witton

Murray

. Causal association between cannabis and psychosis: Examination of the evidence. Br J Psychiatry 2004;184:110–7.

Fergusson

Poulton

Smith

Boden

. Cannabis and psychosis. BMJ 2006;332:172–6.

Semple

McIntosh

Lawrie

. Cannabis as a risk factor for psychosis: A systematic review. J Psychopharmacol 2005;19:187–94.

MacLeod

Oakes

Copello

Crome

Egger

Hickman

, and others. The psychological and social sequelae of cannabis and other illicit drug use by young people: A systematic review of longitudinal, general population studies. Lancet 2004;363:1579–88.

10.

Weiser

Noy

Interpreting the association between cannabis use and increased risk for schizophrenia. Dialogues Clin Neurosci 2005;7:81–5.

11.

Fergusson

Horwood

Swain-Campbell

. Cannabis dependence and psychotic symptoms in young people. Psychol Med 2003;33:5–21.

12.

Fergusson

Horwood

Ridder

. Tests of causal linkages between cannabis use and psychotic symptoms. Addiction 2005;100:354–66.

13.

Henquet

Krabbendam

Spauwen

Kaplan

Lieb

Wittchen

, and others. Prospective cohort study of cannabis use, predisposition for psychosis, and psychotic symptoms in young people. BMJ 2005;330:11–4.

14.

Van Os

Bak

Hanssen

Bijil

de Graaf

Verdoux

Cannabis use and psychosis: A longitudinal population-based study. Am J Epidemiol 2002;156:319–27.

15.

Zammit

Allebeck

Andreasson

Lundberg

Lewis

Self reported cannabis use as a risk factor for schizophrenia in Swedish conscripts of 1969: Historical cohort study. BMJ 2002;325:1199–1201.

16.

Cook

Campbell

. Quasi-Experimentation: Design and Analysis Issues for Field Settings. Chicago (IL): Rand McNally; 1979.

17.

Hall

Degenhardt

Lynskey

The health and psychological consequences of cannabis use. Canberra (AU): Australian Government Publishing Service; 2001.

18.

Fritzsche

Are cannabinoid receptor knockout mice animal models for schizophrenia?

Med Hypotheses 2001;56:638–43.

19.

Glass

The role of cannabinoids in neurodegenerative diseases. Prog Neuropsychopharmacol Biol Psychiatry 2001;25:743–65.

20.

Skosnik

Spatz-Glenn

Park

Cannabis use is associated with schizotypy and attentional dysinhibition. Schizophr Res 2001;48:83–92.

21.

D'Souza

Cho

Perry

Krystal

. Cannabinoid ‘model’ psychosis, dopamine-cannabinoid interactions and implications for schizophrenia. In: Castle

Murray

, editors. Marijuana and Madness. Cambridge (UK): Cambridge University Press; 2004. p 142–65.

22.

Caspi

Moffitt

Cannon

McClay

Murray

Harrington

, and others. Moderation of the effect of adolescent-onset cannabis use on adult psychosis by a functional polymorphism in the catechol-O-methyltransferase gene: Longitudinal evidence of a gene × environment interaction. Biol Psychiatry 2005;57:1117–27.

23.

Hall

Degenhardt

Teesson

Cannabis use and psychotic disorders: An update. Drug Alcohol Rev 2004;23:433–43.

24.

Bromet

Dew

Eaton

Epidemiology of psychosis with special reference to schzophrenia. In: Zahner

GEP

, editors. Textbook of psychiatric epidemiology. New York (NY): Wiley-Liss; 1995. p 283–300.

25.

Gottesman II

Schizophrenia genesis: The origins of madness. New York (NY): WH Freeman; 1991.

26.

Arseneault

Cannon

Poulton

Murray

Caspi

Morritt

. Cannabis use in adolescence and risk for adult psychosis: Longitudinal prospective study. BMJ 2002;325:1212–3.

27.

McGuire

Jones

Harvey

Williams

McGuffin

Murray

. Morbid risk of schizophrenia for relatives of patients with cannabis associated psychosis. Schizophr Res 1995;15:277–81.

28.

Verdoux

Gindre

Sorbara

Tournier

Swendsen

. Cannabis use and the expression of psychosis vulnerability in daily life. Eur Psychiatry 2002;17:180S–180S.

29.

Der

Gupta

Murray

. Is schizophrenia disappearing? Lancet 1990;335:513–6.

30.

Donnelly

Hall

. Patterns of cannabis use in Australia. Canberra (AU): Australian Government Publishing Service; 1994. p 106.

31.

Arendt

Rosenberg

Foldager

Perto

Munk-Jorgensen

Cannabis-induced psychosis and subsequent schizophrenia-spectrum disorders: Follow-up study of 535 incident cases. Br J Psychiatry 2005;187:510–5.

32.

Barnes

TRE

Mutsatsa

Hutton

Watt

Joyce

. Comorbid substance use and age of onset of schizophrenia Br J Psychiatry 2006;188:237–42.

33.

Hall

Assessing the health and psychological effects of cannabis use. In: Kalant

Corrigall

Hall

Smart

, editors. The health effects of cannabis. Toronto (ON): Centre for Addiction and Mental Health; 1999. p 1–17.

34.

Parascandola

Cigarettes and the US Public Health Service in the 1950s. Am J Public Health 2001;91:196–205.

35.

Talley

Kushner

Sterk

. Lung cancer, chronic disease, epidemiology, and medicine, 1948–1964. J Hist Med Allied Sci 2004;59:329–74.

36.

Royal College of Physicians. Smoking and Health. London (UK): Pitman; 1962.

37.

US Surgeon General. Smoking and Health. Washington (DC): US Department of Health, Education and Welfare; 1964.

38.

Greenberg

Lee

JWY

. Psychotic manifestations of alcoholism. Curr Psychiatry Rep 2001;3:314–8.

39.

Isbell

Fraser

Wikler

Belleville

Eisenmen

. An experimental study of the etiology of rum fits and delirium tremens. Q J Stud Alcohol 1955;16:1–33.

40.

Lishman

. Organic psychiatry: The psychological consequences of cerebral disorder: 2nd ed. Oxford (UK): Blackwell Scientific Publication; 1987.

41.

Connell

. Amphetamine psychosis. Maudsley monograph number 5. London (UK): Chapman and Hall, Ltd; 1958.

42.

Bell

The experimental reproduction of amphetamine psychosis. Arch Gen Psychiatry 1973;29:35–40.

43.

Angrist

Sathananthan

Wilk

Gershon

Amphetamine psychosis: Behavioral and biochemical aspects. J Psychiatr Res 1974;11:13–23.

44.

Curran

Byrappa

McBride

Stimulant psychosis: Systematic review. Br J Psychiatry 2004;185:196–204.

45.

Hall

Hando

Patterns of illicit psychostimulant use in Australia. In: Burrows

Flaherty

MacAvoy

, editors. Psychostimulant use in Australia. Canberra (AU): Australian Government Publishing Service; 1993.

46.

Degenhardt

Roxburgh

McKetin

Hospital stays for drug related psychotic episodes in Australia, 1993–2004. Med J Aust. Forthcoming.

47.

Degenhardt

Hall

. The association between psychosis and problematical drug use among Australian adults: Findings from the National Survey of Mental Health and Well-Being. Psychol Med 2001;31:659–68.

48.

Klein

. The flawed basis for FDA post-marketing safety decisions: The example of antidepressants and children. Neuropsychopharmacology 2006;31:689–99.

49.

Dwyer

Ponsonby

Blizzard

Newman

Cochrane

. The contribution of changes in the prevalence of prone sleeping position to the decline in sudden infant death syndrome in Tasmania. JAMA 1995;273:783–9.

50.

Green

Young

Kavanagh

Cannabis use and misuse prevalence among people with psychosis. Br J Psychiatry 2005;187:306–13.

51.

Linszen

Dingemans

Lenior

. Cannabis abuse and the course of recent-onset schizophrenic disorders. Arch Gen Psychiatry 1994;51:273–9.

52.

Grech

Van Os

Jones

Lewis

Murray

. Cannabis use and outcome of recent onset psychosis. Eur Psychiatry 2005;20:349–53.

53.

Roffman

Stephens

. Cannabis dependence: Its nature, consequences and treatment. Cambridge (UK): Cambridge University Press; 2006.

54.

Budney

Moore

. Development and consequences of cannabis dependence. J Clin Pharmacol 2002;42:28S–33S.

55.

Kavanagh

. An intervention for substance abuse in schizophrenia. Behav Change 1995;12:20–30.

56.

Mueser

Bellack

Blanchard

. Comorbidity of schizophrenia and substance abuse: Implications for treatment. J Consult Clin Psychol 1992;60:845–56.

57.

Lehman

Herron

Schwartz

Myers

. Rehabilitation for adults with severe mental illness and substance use disorders: A clinical trial. J Nerv Ment Dis 1993;181:86–90.

58.

Jeffery

Ley

McLaren

Siegfried

Psychosocial treatment programmes for people with both severe mental illness and substance misuse (Cochrane Review). The Cochrane Library: Volume 1. Chichester (UK): John Wiley and Sons, Ltd; 2004. Available: www.mrw.interscience.wiley.com/cochrane/clsysrev/articles/CD001088/frame.html Accessed 2006 February 2.

59.

Jerrell

Ridgely

Comparative effectiveness of three approaches to serving people with severe mental illness and substance abuse disorder. J Nerv Ment Dis 1995;183:566–76.

60.

Ujike

Morita

New perspectives in the studies on endocannabinoid and cannabis: Cannabinoid receptors and schizophrenia. J Pharmacol Sci 2004;96:376–81.

61.

Hall

The mental health risks of adolescent cannabis use. PLoS Med 2006;3:e39.

62.

Patton

Coffey

Carlin

Degenhardt

Lynskey

Hall

Cannabis use and mental health in young people: Cohort study. BMJ 2002;325:1195–8.

63.

Caulkins

Pacula

Paddock

Chiesa

What we can—and cannot—expect from school-based drug prevention. Drug Alcohol Rev 2004;23:79–87.

64.

White

Pitts

Educating young people about drugs: A systematic review. Addiction 1998;93:1475–87.

65.

Tobler

Lessard

Marshall

Ochshorn

Roona

Effectiveness of school-based drug prevention programs for marijuana use. Sch Psychol Int 1999;20:105–37.

66.

Gorman

. On the difference between statistical and practical significance in school-based drug abuse prevention. Drugs Educ Prev Policy 1995;2:275–83.

67.

Gorman

. Etiological theories and the primary prevention of drug use. J Drug Issues 1996;26:505–20.

68.

Hall

Nelson

Correlates of the perceived health risks of marijuana use among Australian adults. Drug Alcohol Rev 1996;15:137–43.

69.

Toumbourou

Williams

Waters

Patton

What do we know about preventing drug-related harm through social developmental intervention with children and young people? In: Stockwell

Gruenewald

Toumbourou

Loxely

, editors. Preventing harmful substance use: The evidence base for policy and practice. Chichester (UK): John Wiley and Sons Ltd; 2004. p 87–100.

70.

Grier

Bryant

. Social marketing in public health. Annu Rev Public Health. 2005;26:319–39.

71.

McBride

A systematic review of school drug education. Health Educ Res 2003;18:729–42.

72.

Saha

Chant

Welham

McGrath

A systematic review of the prevalence of schizophrenia. PLoS Med 2005;5:e141.

73.

Cresswell

Kearney

Weak drug laws linked to madness. The Australian 2005 October 29;Sect 1: All-round Country (p 1).

74.

Hall

The recent Australian debate about the prohibition on cannabis use. Addiction 1997;92:1109–15.

75.

Hall

Pacula

. Cannabis use and dependence: Policy health and public policy. London (UK): Cambridge University Press; 2003.

76.

Donnelly

Hall

Christie

Effects of the Cannabis Expiation Notice Scheme on levels and patterns of cannabis use in South Australia: Evidence from the National Drug Strategy Household Surveys 1985–1995. Canberra (AU): Australian Government Publishing Service; 1999. National Drug Strategy Research Monograph nr 37.

77.

Williams

The effects of price and policy on marijuana use: What can be learned from the Australian experience?

Health Econ 2004;13:123–37.

78.

Single

. The impact of marijuana decriminalization: An update. J Public Health Policy 1989;10:456–66.

79.

MacCoun

Reuter

Drug war heresies: Learning from other vices, times, and places. Cambridge (UK): Cambridge University Press; 2001.

80.

Australian Institute of Health and Welfare. Statistics on drug use in Australia 2004. Canberra (AU): Australian Institute of Health and Welfare; 2005. cat no PHE 62.

81.

Hall

Swift

The THC content of cannabis in Australia: Evidence and implications. Aust N Z J Public Health 2000;24:503–8.

82.

Glantz

Slade

Bero

Hanauer

Barnes

. The Cigarette Papers. Berkley (CA): University of California Press; 1996.