Black Sheep

by Liz McCulloch

To download a PDF version of the report click here.

Black Sheep: An Investigation into Existing Support for Problematic Cannabis Use

Statistical Snapshot

  • It has been estimated that 2.6% of the adult population (aged 16 or over) showed signs of cannabis dependence, which is up to 1,150,000 people, though it is expected that the actual number of people who meet the threshold for clinical dependence will be far lower
  • 21% of adults going through treatment are citing cannabis as a problematic substance
  • 79.7% of adults listing cannabis as a problematic substance are entering treatment voluntarily
  • New presentations among adults for cannabis treatment increased by 55.2% between 2005-2014
  • Among adult non-opiate clients accessing treatment, cannabis users were the most likely to have unchanged use at the 6 month review, which equates to 42% of those who entered treatment
  • Among people showing signs of cannabis dependence, only 14.6% had ever received treatment, help or support specifically because of their drug use, and 5.5% had received this in the past six months

Executive Summary

Cannabis is a neglected drug in public health discourses, a reality which is at odds with the growing number of people in England who are now seeking support for problematic cannabis use. The disparity of how cannabis is prioritised by drug and alcohol service providers, wider community services, local authority commissioners and public health bodies has limited the amount of support available and impeded quality.

  • Among people experiencing problematic cannabis use, there is a perception that their needs will not be effectively met at treatment centres.
  • Some drug and alcohol service providers and commissioners are being attentive to cannabis but overall, cannabis has not been appropriately prioritised.
  • One to one interventions relating to cannabis are mostly confined to drug and alcohol treatment centres. Wider community services reported that they do not have the capacity or the ability to offer brief, initial interventions.
  • There are limited amounts of public resources available, some of which are lacking in levels of quality and accessibility.

A wider structural barrier is that the sector does not have a clear strategy for linking people experiencing problematic cannabis use into support and guidance. With the current illegal and unregulated market reducing the visibility of cannabis use, practitioners reported that ‘we’re just fumbling around in the dark trying to find them’.

Responsibility for change does not just fall to drug and alcohol service providers, and a unified, multi-faceted approach is needed. Evidence of good practice within the sector and contributions from stakeholders and experts has been used to formulate sensible, innovative policy options tailored to the needs of people experiencing problematic cannabis use.

  • Research into the social costs of problematic cannabis use by Public Health England would provide justification for commissioners to appropriately prioritise cannabis within treatment. Commissioner specification of cannabis would incentivise providers to utilise existing resources and supply innovations targeted towards people experiencing problematic cannabis use.
  • A shift towards holistic service provision and promotion by drug and alcohol service providers and wider community services, would aim to increase interaction and engagement with support.
  • A move towards a regulated market would offer a targeted dialogue with people experiencing problematic cannabis use, providing opportunities for harm reduction advice to be delivered at point of purchase and persons in need of support relating to their cannabis use to be linked into reformed public health measures. There would also be the emergence of wider opportunities for more public guidance, packaging controls, products which vary in potency, research into cannabis culture and consumption to improve interventions, and reduced stigma to enable access to services.

Effective support requires public health measures which appropriately prioritise the needs of people experiencing problematic cannabis use and a regulated market which targets these measures to their intended audience.

2.6% of the adult population (aged 16 or over) showed signs of cannabis dependence.


It should be emphasised that cannabis is not as dangerous as many other drugs,[footnote]Nutt, D., King, L., Phillips, K. 2010. Drug harms in the UK: a multicriteria decision analysis. The Lancet. 376(9752), pp.1558–1565.; Amsterdam, J., Nutt, D., Phillips, L., Wim, B. 2015. European Rating of Drug Harms. Journal of Psychopharmacology. 29(6), pp.655–660.[/footnote] with treatment centres historically focusing on opiates and crack cocaine which have higher associated harms.[footnote]Adult treatment services in the UK have predominantly targeted problematic opiate and crack cocaine users. This is due both to the historic rarity of cannabis referrals in comparison to other drugs and the development of UK drug treatment policy, which in the 1980s prioritised responses to users of drugs most associated with blood borne viruses.(National Treatment Agency. 2010. Injecting Drug Use in England: A Declining Trend.) Attention was given to problematic cannabis use under the Blair government with cannabis specific services being commissioned. This emphasis was reduced in the 2008 Drug Strategy. Though the 2008 strategy supported recovery from all drug use, the implicit focus was on crack cocaine and opiates, particularly the latter.(Drugs: Protecting Families and Communities. The 2008 Drug Strategy. HM Government.)
The 2010 strategy evolved treatment by reducing the focus on acquisitive crime and harm reduction, instead taking a moral position on ‘recovery’ and the need for abstinence, which was seen as a prerequisite for being a contributing member of society.(Reducing Demand, Restricting Supply, Building Recovery: Supporting People to Live a Drug Free Life. The 2010 Drug Strategy. HM Government.)[/footnote] As with many other substances with a potential for dependence and misuse, most people do not develop a problematic relationship with their cannabis use,[footnote]Hall, W., Pacula, R. 2003. Cannabis use and dependence: Public health and public policy. Cambridge: Cambridge University Press.[/footnote] but for a proportion of people, usage can become problematic and may stop them from living meaningful and fulfilling lives. It is these people who are the focus of this report.[footnote]Drug and Alcohol practitioners were asked whether they felt that synthetic cannabinoid receptor agonists (SCRAs) were a growing issue within the services. The overall response was that SCRAs only affected a very small proportion of their clients and were perhaps more relevant in services which specifically target groups with complex needs where use is more prevalent, examples included ex-offenders and people experiencing homelessness.[/footnote]


The most recent Adult Psychiatric Morbidity Survey has estimated that 2.6% of the adult population (aged 16 or over) showed signs of cannabis dependence,[footnote]McManus, S., Bebbington, P., Jenkins, R., Brugha, T. 2016. Mental health and wellbeing in England: Adult Psychiatric Morbidity Survey (eds). Leeds: NHS Digital.[/footnote] which is estimated to be up to 1,150,000 people.[footnote]Population Estimates for UK, England and Wales, Scotland and Northern Ireland. Office for National Statistics. 2015.; Authors of the Adult Psychiatric Morbidity Survey have highlighted that their estimates may be under representing true rates due to socially undesirable and stigmatised feeling resulting in underreporting and the sampling frame only covering those living in private households. It is clarified though that the proportion of people not living in private households would only have a small effect (2014, pp.350-352). Problematic cannabis use will be the preferred term used in this paper but cannabis dependence is also used commonly in the literature. The term cannabis dependence will be used when it is relevant to the methodology of the citation.[/footnote] Caution should be taken with this figure, however, as the Adult Psychiatric Morbidity Survey defines signs of dependence as responding positively to any one of the five criteria for dependence it lists. The survey notes that responding to three or more of these criteria is closer to the threshold for drug dependence defined in ICD-10. Volteface have issued a Freedom of Information request to establish the figure corresponding to this tighter definition of dependence from the Adult Psychiatric Morbidity Survey, which is expected to be substantially lower than the survey’s definition for signs of dependence. The 2015 England and Wales Crime Survey estimates 3.7% of 16-59 year olds in England and Wales are frequent cannabis users, which corresponds to 800,000 people, and only a subset of these will fit ICD-10 criteria for cannabis dependence.[footnote]Lader, D. 2016. Drug Misuse: Findings from the 2015/16 Crime Survey for England and Wales. 2nd edition. Home Office. Office of National Statistics.[/footnote] This gives an indication of the smaller number of people likely to fit a tighter definition of cannabis dependence.

Explaining Problematic Cannabis Use

The most The International Statistical Classification of Diseases and Related Health Problems provide widely used clinical definitions of cannabis use disorders and cannabis withdrawal which have been integrated into the diagnostic criteria for substance misuse (DSM-5).[footnote]Genen, L., Haning, W., Burns, J. 2016. Cannabis Related Disorders Clinical Presentation. Medscape. (online)[/footnote] However, problematic cannabis use can be more widely defined as ‘use leading to negative consequences on a social or health level, both for the individual user and for the larger community’,[footnote]Preedy, V. 2016. Handbook of Cannabis and Related Pathologies. London: Academic Press. p.182[/footnote] with various other concepts encompassed within it such as misuse, abuse, and dependence.[footnote]European Monitoring Centre for Drugs and Addiction. 2008. A cannabis reader: global issues and local experiences, Perspectives on cannabis controversies, treatment and regulation in Europe. Lisbon. Luxembourg: Office for Official Publications of the European Communities. p.31[/footnote]

The guide on the assessment and management of problematic cannabis use in primary care by Winstock et al.[footnote]Winstock, A., Ford, C., Whitton, C. 2010. Assessment and management of cannabis use disorders in primary care. British Medical Journal. 340, c1571.[/footnote] highlights that the patient will likely be a long term, heavy daily user, who may experience:

  • Respiratory problems, such as exacerbation of asthma, chronic obstructive airways disease, wheeze or prolonged cough, or other chest symptoms
  • Mental health symptoms, such as anxiety, depression, paranoia, panic, depersonalisation, exacerbation of an underlying mental health condition
  • Problems with concentration while studying or with employment and relationships
  • Difficulties stopping cannabis use
  • Legal or employment problems (arising from use of cannabis)

The exacerbation of schizophrenia,[footnote]Gage, S., Jones, H., Burgess, S., Bowden, J. 2016. Assessing causality in associations between cannabis use and schizophrenia risk: a two-sample Mendelian randomization study. Psychological Medicine, pp.1-10.[/footnote] has been the most widely reported adverse effect of cannabis but less attention has been paid to the less severe mental health problems associated with problematic cannabis use, such as anxiety and depression, which are far more common.[footnote]Curran, V., Freeman, P., Mokrysz, C., Lewis, A., Morgan, J., Parsons, H. 2016. Keep off the grass? Cannabis, cognition and addiction. Nature Reviews Neuroscience. 17(5), pp.293-306.[/footnote]

Taylor et al. have also concluded that after controlling for tobacco, ‘significant respiratory symptoms and changes in spirometry occur in cannabis-dependent individuals at age 21 years, even though the cannabis smoking history is of relatively short duration’.[footnote]Taylor, D., Poulton, R., Moffitt, T., Ramankutty, P., Sears, M. 2000. The respiratory effects of cannabis dependence in young adults. Addiction. 95(11) pp.1669-77.[/footnote] The physical health impacts then become more pronounced when considering that the majority of cannabis users consume cannabis with tobacco.[footnote]European Monitoring Centre for Drugs and Addiction. 2016. European Drug Report: Trends and Developments. Luxembourg: Publications Office of the European Union.[/footnote]

The are also wider social difficulties associated with problematic cannabis use, with international evidence cautiously indicating that people who are dependent on cannabis are also at greater risk of downward social mobility and financial difficulties when compared to those who use cannabis but are not dependent. The NZ Dunedin Longitudinal Study[footnote]Cerdá, M., Moffitt, T., Meier, M., Harrington, L., Houts, R., Ramrakha, S., Hogan, S., Poulton, R., Caspi, A. 2016. Persistent Cannabis Dependence and Alcohol Dependence Represent Risks for Midlife Economic and Social Problems: A Longitudinal Cohort Study. Association for Psychological Science. 4(6), pp.1028-1046.[/footnote] studied participants from birth to age 38 and found that those with regular cannabis use and persistent dependence experienced downward socioeconomic mobility, more financial difficulties, workplace problems, and relationship conflict in early midlife. It should be noted that this finding was modelled on a small sub-sample as only 23 participants were assessed as being dependent at all study waves.

All drug taking has risk and cannabis is no different.

Chris’s Story

“For me drugs are all about how a person is brought up. Growing up my parents didn’t set boundaries and they didn’t educate me to build resilience needed for adulthood. So, like many other of my mates I got drunk for the first time when I was 12, and smoked cannabis at the age of 13.

I was smoking cannabis during my time at the navy as there was plenty of trips ashore where you would be able to smoke, but it was just recreational. It wasn’t really till I left the navy that I became a habitual smoker but I would never have considered it a problem, it was just part of the smoking culture.

But it was having a problem on my life. I was smoking and inhaling for longer so in terms of my health it was having an effect and I knew the quantities I was using wasn’t good.

I was using cannabis to calm down the other drugs I was taking and I was blocking out the negative consequences of those drugs. It became a substance within all those other substances I had to deal with.

Your life revolves around getting up in the morning and playing cards and having a big spliff with your flatmate. There are other people that can wake up in the morning and take a spliff, but that didn’t work for me. All drug taking has risk and cannabis is no different.”

Rising Demand for Treatment

Between 2005-2014, new treatment presentations where cannabis was the primary drug of use have increased by 55.2% (see Figure 1.1).[footnote]Data reflects new treatment presentations rather than proportion of client group citing cannabis as a problematic substance. Cannabis primary presentations for 2014/15 and 2015/16 have not been published though it has been reported that the increase is levelling out.; Public Health England., University of Manchester., National Drug Evidence Centre., Department of Health. 2014. Adult substance misuse statistics from the National Drug Treatment Monitoring System (NDTMS) 1 April 2013 to 31 March 2014. Public Health England.[/footnote]

Figure 1.1 New cannabis treatment presentations in England from 2005 to 2014.

There has been no clear agreement on why cannabis referrals have increased in recent years, and though many reasons have been espoused, none have been fully substantiated. Firstly, there is the ‘build it and they shall come’ explanation, with the argument that additional funding given under the Blair government and a declining number of opiate users in treatment  has allowed services to accept more referrals for people experiencing problematic cannabis use.

However, though there was substantial funding given during the Blair government, the rise in referrals continued despite subsequent reductions in funding for cannabis related treatment. Moreover, even though there are fewer opiate users entering treatment, the ageing heroin cohort have higher levels of complexities and require more resource and innovation from services to engage in treatment.[footnote]Advisory Council on the Misuse of Drugs. 2016. Reducing Opioid-Related Deaths in the UK. Home Office.[/footnote]

The second commonly cited argument is that high potency cannabis use is associated with increased incidences of harm,[footnote]Curran, V., Freeman, P., Mokrysz, C., Lewis, A., Morgan, J., Parsons, H. 2016. Keep off the grass? Cannabis, cognition and addiction. Nature Reviews Neuroscience. 17(5), pp.293-306.[/footnote] with a correlation emerging between prevalence of high potency cannabis and numbers in treatment, as illustrated by Figure 1.2.[footnote]Freeman, T., Winstock, A. 2015. Examining the profile of high-potency cannabis and its association with severity of cannabis dependence. Psychological Medicine. 45(15), pp.3181–3189.[/footnote] However, this evidence is not conclusive as there have only been three recorded data points on cannabis potency,[footnote]Hardwick, S., King, L. 2008. Home Office Cannabis Potency Study. Home Office Scientific Development Branch.[/footnote] and criticisms have been made of the data collection practices.[footnote]Monaghan, M., Hamilton, I. 2016. Is cannabis really getting stronger? The Conversation, 1 August.[/footnote]

Figure 1.2 Prevalence of high potency cannabis and number of adults in cannabis treatment over time.

79.7% of adults listing cannabis as a problematic substance are entering treatment voluntarily.

Referral Routes

What is known is that the 79.7% of adults listing cannabis as a problematic substance are entering treatment voluntarily. An FOI request showed that among the clients who cited cannabis as a problematic substance, the majority of referrals came from the client, family and friends,[footnote]Volteface. 2016. Referral routes for clients citing cannabis as a problematic substance. Freedom Of Information Request. (See appendix)[/footnote] with recently released statistics from the National Drug Treatment Monitoring System also confirming that non-opiate users were most likely to enter treatment voluntarily.[footnote]Public Health England., University of Manchester., National Drug Evidence Centre., Department of Health. 2016. Adult substance misuse statistics from the National Drug Treatment Monitoring System (NDTMS) 1st April 2015 to 31st March 2016. Public Health England.[/footnote]

It is worth considering that the proportion of self referrals may be over estimated, as contributors reported that some clients may have been told by probation that they must seek treatment or other action would be taken. However, it was also noted that this example would only reflect a very small number of cases and it was rare for services to receive a referral for non-problematic use. Furthermore, a combined referral source of self, family, and friends does leave unanswered the question of whether significant numbers of clients are coerced by family or friends. While it is possible that some clients are being pressured into treatment, the client group are adults who are ultimately free to make their own decisions. Moreover, even if a person were coerced into treatment, this does not mean that there is no problem, nor that meaningful work cannot take place.

Proportion of Client Group

Though the increase in clients citing cannabis as a problematic substance is worthy of further investigation, the data which is perhaps of most interest is simply the proportion of people who are citing cannabis as a problematic substance in treatment centres. NDTMS data shows that cannabis accounts for 21% of all problematic substances cited in treatment centres (Public Health England et al, 2016).[footnote]Public Health England., University of Manchester., National Drug Evidence Centre., Department of Health. 2016. Adult substance misuse statistics from the National Drug Treatment Monitoring System (NDTMS) 1st April 2015 to 31st March 2016. Public Health England.[/footnote] Contributors highlighted that many clients will be citing other substances such as alcohol, opiates, or crack cocaine, and their cannabis use (even though deemed problematic) might be incidental to them being in treatment. Even though cannabis may not be the primary need for many clients, it is being cited as a problematic substance by a significant proportion of clients and should not be disregarded even if it is a secondary need.

This paper will examine the public health response to cannabis and identify the barriers and opportunities for effective support.


Volteface undertook unstructured interviews with a broad range of stakeholders and experts to better understand the public health response these trends. Interviewees were asked how current public health measures were engaging people experiencing problem cannabis use and whether the measures were addressing the full spectrum of need. This paper reports on the key themes emerging from these discussions and consultations. Interviewees were selected through Volteface’s network of contacts, including stakeholders who were not engaged with drug policy reform. A limitation to the research is that drug and alcohol service providers are operating in a competitive market and may have been reluctant to disclose information which could be viewed negatively by their commissioners or risk their reputation. To encourage interviewees to speak candidly, contributions have not been attributed to individual persons. Providers who offered specific examples of good practice have been named to enable information sharing within the sector.

After conducting an initial consultation with professionals and identifying key themes, a public survey of open questions was launched, asking people who had experienced a problematic relationship with cannabis, for their opinion on the validity of these findings. The survey received 41 responses.[footnote]28 of survey respondents were male, 2 preferred not to disclose their gender and 11 skipped the question. Though it has been reported that men are most likely to experience problematic cannabis use, women were underrepresented in this sample. There was a greater distribution of age with 25-44 year olds being the most common category, again reflective of the demography of problematic cannabis use.
European Monitoring Centre for Drugs and Drug Addiction. 2013. Perspectives on Drugs: Characteristics of frequent and high-risk cannabis users. Luxembourg: Publications Office of the European Union.[/footnote]

Drawing from these consultations and wider literature, this paper will examine the public health response to cannabis and identify the barriers and opportunities for effective support. Stakeholders who we believe will find this report useful include drug and alcohol service providers, commissioners, GPs, Public Health England, the Home Office, the Department of Health and the ACMD, with different sections of the report relevant for different audiences. The conclusions of this report are not intended as guidelines for clinicians but rather aim to highlight policies which would improve the public health response to problematic cannabis use. Though wider structural problems, such as cuts to service provision, do impede effective support, only findings which specifically relate to cannabis will be included in the paper. The first section will address how well the current system engages and supports adults experiencing problematic cannabis use, whilst the second section will make practical policy recommendations.

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