The Health & Social Effects of Non-Medical Cannabis Use

Transcription

1 The Health & Social Effects of Non-Medical Cannabis Use The State of Knowledge: Knowns & Unknowns Maria Renström Department of Mental Health & Substance Abuse

2 Background Process: The Health & Social Effects of Non-Medical Cannabis Use 1995 WHO Expert Meeting on Cannabis 1997 Cannabis: A Health Perspective and Research Agenda 2015 WHO Expert Meeting on the Effects of Cannabis and Cannabis Use Disorders on Health and Psychosocial Functioning Review and synthesize best available evidence on impact of cannabis use and cannabis use disorders on health Address health system responses to cannabis use disorders and other health disorders cause by or associated with cannabis use Identification of priorities for international research; intended to contribute to preparations for the special session of the UN General Assembly on the World Drug Problem in April 2016 Medical use of cannabinoids is outside the scope of this effort 37 th session of the ECDD, cannabis on the agenda 2016 Planned new updated report 2

3 Background Global Prevalence of Use Cannabis is the most commonly used illicit substance in the world; globally, 181.8M individuals aged 15 to 64 years reported using cannabis in Lifetime prevalence of cannabis use varies considerably Use appears to be more common in developed than developing countries European prevalence of cannabis use estimates range between 1.0% to 45.1% (among adolescents and young adults aged 15 to 34) Weighted European average of lifetime prevalence of cannabis use: 32.2% M (11%) young Europeans have used cannabis in the past 12 months. 1. UN World Drug Report

4 Distribution of past year cannabis users aged years, by UN Region UNODC, World Drug Report 2013 Eastern and South-Eastern Europe 3% Near and Middle East/South East Asia 5% South Asia 19% East and South-East Asia 6% Oceania 2% Western and Central Europe 10% East Africa 4% South America 9% Central and Transcaucasia 1% North Africa 3% South Africa 2% West and Central Africa 16% North America 20% Caribbean 0% Central America 0% East Africa North Africa South Africa West and Central Africa Caribbean Central America North America South America Central and Transcaucasia East and South-East Asia Near and Middle East/South East Asia South Asia Eastern and South-Eastern Europe Western and Central Europe Oceania 4

5 Mental Health & Psychosocial Effects Prevalence of Cannabis Dependence 5 Humans develop tolerance to THC and cannabis users who seek help often report withdrawal symptoms Regular cannabis users can develop dependence approximately 1 in 10 and 1 in 6 in those who start in adolescence Degenhardt L, Ferrari AJ, Calabria B, Hall WD, Norman RE, McGrath J, Flaxman AD, Engell RE, Freedman GD, Whiteford HA, Vos T. (2013) The Global Epidemiology and Contribution of Cannabis Use and Dependence to the Global Burden of Disease> Results from the GBD 2010 Study. PLoS One 8(10); e76635 doi: /journal.pone

6 Mental Health & Psychosocial Effects Cannabis Dependence 6 Degenhardt L, Ferrari AJ, Calabria B, Hall WD, Norman RE, McGrath J, Flaxman AD, Engell RE, Freedman GD, Whiteford HA, Vos T. (2013) The Global Epidemiology and Contribution of Cannabis Use and Dependence to the Global Burden of Disease> Results from the GBD 2010 Study. PLoS One 8(10); e76635 doi: /journal.pone

7 Mental Health & Psychosocial Effects Cannabis Dependence 7 Degenhardt L, Ferrari AJ, Calabria B, Hall WD, Norman RE, McGrath J, Flaxman AD, Engell RE, Freedman GD, Whiteford HA, Vos T. (2013) The Global Epidemiology and Contribution of Cannabis Use and Dependence to the Global Burden of Disease> Results from the GBD 2010 Study. PLoS One 8(10); e76635 doi: /journal.pone

8 Summary of Knowledge Gaps Prevalence of Use & Dependence Limited data on the standard doses used of cannabinoids among the users More data on routes of administration and titration methods used necessary Limited data on cannabis potency trends over time Limited data from LMICs, most epidemiological research on cannabis has been about smokers in a small number of developed countries Cannabis and tobacco are often mixed together; we lack data on the prevalence and health consequences of different administration methods and routes Use of cannabis in combination with tobacco THC and other content of pressed marijuana in Latin American countries 8

9 Summary of Knowledge Gaps Prevalence of Use & Dependence Most of the studies on risk and protective factors for cannabis have been conducted in a limited number of high-income countries Uncertain whether the same risk factors apply in developing countries Global data are lacking on trends in the prevalence of frequent and heavy cannabis use and cannabis dependence It is also uncertain whether increased treatment seeking by cannabis users is linked to higher THC in cannabis products 9

10 Background Effects on Health Health is a state of complete physical, mental, and social well-being and not merely the absence of disease or infirmity. Short-term effects on health are those that arise from a single occasion of use of from relatively few occasions of use and occur close together in time The most obvious short-term health effect of cannabis is intoxication marked by disturbances in the level of consciousness, cognition, perception, affect or behaviour, And other psychophysiological functions and responses Long-term effects on health are those that arise from regular cannabis use especially daily use over periods of months, years, or decades A major challenge exists in interpreting associations between cannabis and adverse health outcomes in epidemiological studies Regular users have higher risks of negative outcomes given a propensity toward polysubstance use Short-term Effects Cognitive and psychomotor function impairment Altered 10 sense of time perception Long-term Effects Cognitive Decline Impairment in learning, memory and executive functioning Impaired awareness and alertness Dopamine synthesis capacity reduced

11 What defines the harms to health by nonmedical use of cannabis? The severity of the harm relates to: The properties of the substance itself The form and mode of administration used The characteristics of the person taking The social context in which it is taken 11

12 What do we know about - Neurological Effects The brain s dopamine reward system contains both kinds of CB receptors. (CB1 and CB2) CB receptors respond to THC by increasing dopamine release, explaining the euphoric effects of cannabis. Dopamine release is involved in cognition, attention, emotionality, and motivation all are affected with cannabis exposure Cognitive and psychomotor function are impaired directly after cannabis use receptor mediated activity within the cerebellum may explain the association to driving impairment and visual tracking Exposure to cannabis during critical developmental periods ( children and young peope) is of particular importance as it has detrimental, potentially irreversible health and social effects on the life trajectory 12

13 What do we know about - Long-term Neurological Effects Long term use of cannabis down-regulates CB 1 receptors in neural regions associated with memory and cognition THC exposure during puberty amplifies effect SPECT Scan analyses find large decreases in perfusion in comparative studies among long-term cannabis users and non-using controls; these studies also find poorer cognitive performance among longterm users 2 Adults who have smoked cannabis since adolescence have less neuronal connectivity in prefrontal areas that are responsible for executive functioning and inhibitory control in subcortical networks responsible for habits and routines For frequent users, neurocognitive effects can last over 7 days and possibly up to 30 days EFFECTS OF CHRONIC CANNABIS EXPOSURE ON BRAIN STRUCTURES Percuneous - Awareness - Alertness Fimbria - Learning - Memory Dopamine Synthesis - Decreased capacity General Structural Changes - Global brain measures - White/Grey matter - Reduced volume in: - Hippocampus - Amygdala - Cerebellum - Frontal cortex Mena I et al. (2013). Efectos del consumo de marihuana en escolares sobre funciones cerebrales demostrados mediante pruebas neuropsicológicas e imágenes de neuro-spect [Effects of consuming marijuana on school students brain functions demonstrated through neuropsychological testing and neuro-spect imaging]. Salud mental, 36:

14 What do we know about - Acute Effects: Cannabis Intoxication Risk of a fatal cannabis overdose is extremely small relative to opioids and stimulant drug overdoses Currently no reports of a cannabis-related fatal overdose in the epidemiological literature Cannabis users typically smoke dried herb and take deep inhalations holding the smoke in their lungs as long as they can Facilitates THC absorption Effects are felt nearly immediately, peak absorption occurs within 9-30mins following use Tachycardia can be a sign of cannabis intoxication CB 1 and CB 2 are both found in the cardiovascular system Effects of intoxication include: panic attacks, slowed reaction time, increased risk of MVAs, sleep disruption etc. 14

15 What do we know about - Acute Effects: Cardiopulmonary System Acute cannabis exposure increases heart rate and blood pressure and can cause orthostatic hypotension Bronchial effects differ around the world depending on the mode of administration Tobacco smoking produces acute bronchial constriction Cannabis smoking produces acute bronchial dialation 15

16 What we know and do not know about - Acute Effects: MVAs, Injuries, and Suicides Cannabis users who drive while intoxicated double their risk of a motor vehicle accident A moderate causal relationship has been established between cannabis use and traffic injuries Mixed epidemiological study findings exist on cannabis consumption and general injury risk At present, there is not enough evidence to determine whether acute cannabis use influences risk of suicidal behaviour 16

17 What we know about long-term cannabis use and - Cardiovascular Disease Limited studies exist regarding cannabis users and CVD Recent case reports suggest that cannabis smoking may increase CVD risk in younger cannabis smokers otherwise at low risk of CVD Case studies have found associations between cannabis smoking and ischemic stroke Cannabis-associated strokes usually occur in chronic or current cannabis users who smoke tobacco Cannabis smoking may increase CVD risk by increasing carboxyhaemoglobin levels 17 Wolff V et al. (2011) Cannabis use, ischemic stroke, and multifocal intracranial vasoconstriction: a prospective study in 48 consecutive young patients. Stroke, 42(6):

18 What we know about long-term cannabis use and - Cancer Cannabis smoke is carcinogenic in microbial assays; THC and other cannabinoids themselves are not Upper arerodigestive cancers Pooled analyses have not found an association for head and neck cancers Respiratory cancers Pooled analyses have not found an association between cannabis smoking and lung cancer Testicular cancer Cannabinoid receptors are found in the male reproductive system; an increased risk (OR=1.5) for high frequency cannabis users as well as those smoking for a decade or more Other cancers Some study on smoking during pregnancy could be associated with cancers among children Larger cohort and better designed case/control studies that better control for tobacco smoking needed to clarify respiratory cancer risk 18

19 Factors increasing vulnerability to drug use. Source: World Drug Report 2015

20 What we know about - Prevention of Cannabis Use Most cost-effective: interventions to prevent use or delay age of onset that have been especially beneficial or likely beneficial in their impact on use of cannabis - targeting a range of behaviours : Interventions targeting families Likely beneficial if parents, children, and the family collectively involved effective in reducing lifetime and past year cannabis use in adolescents ( Gates et al., 2006) Interventions targeting vulnerable youth Interactive social programs effective in reducing past month cannabis use Life skills development, team building, interpersonal communication skills, introspective learning etc. Involvement in community, school, and family ( Springer et al., 2004) Intervention targeting school settings Programs that include social competence curriculum and social influence approaches Interactive drug curricula Peer-led interventions using peer educators in school settings ( Faggiano.et al., 2005 and 2010) 20

21 What we know about - Treatment for Dependence & Intoxication Effective treatments for dependence include: Combinations of: Cognitive Behavioural Therapy ( also stand alone) Motivational Enhancement Therapy Contingency Management Family/Social Interventions Pharmacological treatment for intoxication: Various drugs have been used to manage negative or acute adverse effects of cannabis: (Beta-blockers, antiarrhythmic agents, CB1 and GABA-benzodiazepene receptor antagonists, antipsychotics, and cannabidiol. Propranol, flecainidine, propafenone, flumazenil, olanzapine, and haloperidol) More research required for treatment of cannabis acute effect 21

22 What we know about - Treatment Coverage ( Substance use): ATLAS % 1 to 10% 10-20% 21-40% >40% Unknown Low income (N=21) Lower middle-income (N=38) Higher middle-income (N=38) High income (N=48) Global (N=146) 22

23 What we know about - Access to Treatment ( substance use) : ATLAS % 11-20% 21-50% 50-90% 90-98% % Unknown Low income (N=20) Lower middle-income (N=36) Higher middle-income (N=38) High income (N=48) Global (N=143) 23

24 What we know about - Cannabis and Treatment Entry: ATLAS Cannabis ranked first as primary drug at treatment entry Low income (N=22) Lower middle-income (N=40) Higher middle-income (N=42) High income (N=49) Global (N=154) 24

25 Summary of Knowledge Gaps Health & Social Impact Measure of THC content of cannabis products currently used How does this influence effects on health? Is the increased THC content responsible for increased rates of individuals seeking treatment? Typical dose of THC typically consumed Patterns of use in terms of emerging forms and modes of administration 25

26 Summary of Knowledge Gaps Health & Social Impact Reversibility of adverse effects on the human body particularly important for those exposed early in life Permanence of neurobiological changes The influence of genes and environment on individuals behaviours Reproductive effects particularly use of cannabis during pregnancy or conception 26

27 Summary of Knowledge Gaps Health & Social Impact Impact on incidence of non-communicable diseases Carcinogenic effects on respiratory, cardiovascular, and male reproductive systems Risks of mental disorders including: psychoses, particularly schizophrenia, mood disorders, bipolar disorder, suicide etc. Poly substance use 27

28 Recommendations Policy Options Governing bodies should opt for approaches that respond to non-medical use of cannabis supported by a strong evidence base in terms of prevention, treatment, and rehabilitation Independent evaluations and analyses of options adequate for respective jurisdictions should be conducted to determine appropriate action sensitive to needs of the population of interest Consider surveillance or more sensitive surveillance instruments containing currently unknown indicators of problematic cannabis use and related disorders 28

29 Moving Forward Areas of Future Research 1. Global prevalence data/measures of non-medical cannabis use and mental disorders and related conditions 2. Effects of long-term cannabis use on neurobiology and the risks of mental disorders including psychoses, in particular schizophrenia, mood disorders, bipolar disorders, suicide etc. 3. Social and economic costs of cannabis use and cannabis use disorders 29

30 Moving Forward Areas of Future Research 4. Consensus on operational terms related to data collection on cannabis use disorders, heavy use of cannabis, problematic use of cannabis etc. 5. Effect of cannabis use (alone) on incidence of noncommunicable disease such as COPD and cancers 6. Cost-effectiveness of existing interventions, treatment and rehabilitation modalities 30

31 Thank you! 31