Rethink: cannabis education is key to drug classification debate
The mental heath charity Rethink today (July 31) called on the government to deliver on its promise to launch a long-term public health campaign on the links between cannabis and mental health, following the publication of the Science and Technology Committee Report on drug classification.
Rethink’s Director of Public Affairs Paul Corry said: “In any debate about the classification of cannabis, Rethink’s main concern is that the government delivers on its promise to educate the public about the mental health risks of cannabis use.
“We share the concerns of Phil Willis, Chairman of the Science and Technology Committee, that young people need evidence of the harm drugs can do. On mental health the evidence is there – but people need to be told about it.
“That’s why Rethink recently launched a cannabis survey to find out people’s knowledge and attitude towards cannabis, which we hope will provide a baseline to help future awareness projects.”
Mr Corry added: “Rethink is concerned by the lack of progress concerning this critical public health issue. We know that early-age users, long-term users and people with a family history of mental illness are at a high risk of developing psychosis from smoking cannabis – the problem is that they don’t know it because the government has failed to act on its promise.”
Mr Corry added: “In France, millions of euros are being spent on taking mental health warnings to young people. If the Government wants to be taken seriously it needs to do the same.”
Rethink has been at the forefront of campaigning about cannabis and its links to psychosis and was the first mental health charity to campaign to highlight these risks to the general public. For years, Rethink has been calling for:
- a long-term public health campaign to raise awareness of the link between cannabis and mental illness
- more research to fully understand the effects of cannabis use on mental health
- drugs education in schools on cannabis and mental health.
Notes to editors
Cannabis and mental illness – Briefing January 2006
What is the link between cannabis use and mental illness?
Worsening symptoms
There is a general consensus that long-term cannabis use, and sometimes short-term cannabis use, worsens psychotic symptoms (paranoia, hallucinations and delusions) among people with schizophrenia. This is also true for people with bipolar affective disorder (manic depression) experiencing psychotic symptoms.
‘Trigger’ effect
There is strong evidence from a wide range of sources that long term and short-term use of cannabis can “trigger” a psychotic episode of psychosis in people who are at high risk of developing psychosis – for instance, people who have close family members who have schizophrenia.
Causal link?
There is a growing body of evidence that suggests cannabis may be a causal factor in the development of psychosis. This does not mean that cannabis is a necessary or sufficient cause of psychosis - it is clear that many people use cannabis and do not develop psychotic symptoms; conversely, many people who have psychotic symptoms have never used cannabis.
However, cannabis may be a causal factor. For example, flamingos only become pink if they eat shrimps; other animals, though, do not become pink when they eat shrimps. Shrimps play a causal role in pinkness, but they alone cannot cause pinkness.
There is emerging epidemiological evidence that long-term use of cannabis, particularly if commencing in teenage years, can lead to increasing numbers of people developing the illness. A study by Jim Van Os (2004) of 2,500 adolescents found that among those who had no vulnerability to psychosis, cannabis had a marginal effect, increasing the chances of psychotic symptoms by 6.3%. However, among those who had a predisposition to psychotic symptoms, cannabis use increased almost doubled their chance of developing these symptoms (the risk went from 26.2% to 50%).
A different study (Fergusson et al, 2004) suggested that people who used cannabis daily increased their chances of psychotic symptoms by 1.6-1.8 times. A sophisticated technique called structural equation modelling was used to investigate the possibility that cannabis use was increased by psychotic symptoms, rather than the other way round. The findings of this study suggest that this is not the case and that the level of psychotic symptoms is to be explained by cannabis use.
This population research has been underwritten by research on the effects of cannabis on brain chemistry and functioning.
Treatment?
Some preliminary work has been done on the possibility of using one active ingredient of cannabis in the treatment of psychosis. In one study, people with schizophrenia who received a dose of cannabidiol experienced fewer side effects, less weight gain and prolaction compared with a similar group of people using amisulpride. Both groups experienced a similar decrease in psychotic symptoms. This is promising, but there needs to be a great deal more research before we can make any claims about the therapeutic benefit of cannabidiol.
In any case, cannabidiol is only one of the sixty active ingredients in cannabis. Even if cannabidiol does prove to have a therapeutic effect on psychotic symptoms, this does not change the evidence on cannabis itself.
What is the Government saying and doing about this?
The Government seems to be taking the possibility of cannabis playing a causal role more seriously. A spokesman from the Department of Health acknowledged in January 2005 that:
"There is medical clinical evidence now that there is an important causal factor between cannabis use and schizophrenia - not the only factor, but an important causal factor. That is the common consensus among the medical fraternity."
In March 2005, the Home Secretary asked the Advisory Council on the Misuse of Drugs to consider the evidence on cannabis and mental illness and the question of classification of cannabis. Rethink staff and a service user gave evidence to the Council in September 2005 and they are expected to issue a report by the end of the year.
The Home Office and Department of Health are developing information materials about cannabis for people who have mental illness. However this project only has a budget of £230,000 so it is unlikely that materials will reach everyone who needs this information.
What more should be done about this?
Rethink believes that many young people view cannabis as a risk-free drug; often it is viewed as less harmful than tobacco. Reclassification to class C has created a confusing picture about the risks of cannabis. However, Rethink does not believe that a further reclassification to class B would resolve this issue – that will create more confusion and further undermine the Government’s credibility on the issue. What is needed is better public education, better information for people with mental illness and more research.
A long-term, well-funded public information campaign aimed at publicising the mental health risks associated with cannabis is essential to counter the “risk-free” message. It is particularly important that people aware of vulnerability to psychotic illnesses in their family are informed of the potential dangers of cannabis use.
It is also essential that people who have already developed mental illness become aware of the potential dangers of cannabis use. The project to deliver information to people with severe mental illness needs better, more long-term funding.
More research is essential to clarify the effect of cannabis on mental health and pre-existing mental illness.
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Lana Savic, Media Manager:
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Alita Howe, Media Officer:
tel 020 7330 9149, mobile 07918 660760
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About Rethink severe mental illness
Rethink, the leading national mental health charity, works to help everyone affected by severe mental illness recover a better quality of life. We aim to provide hope and empowerment through effective services and support to all those who need us and campaign for change through greater awareness and understanding.
For further information on the charity and its work continue to browse this website or call 0845 456 0455.
