Briefing - Cannabis and mental health
In his announcement on cannabis to the House in January 2006, Charles Clarke stated:
- “the mental health effects of cannabis are real and significant … We accept the growing body of research that suggests that cannabis may exacerbate or even trigger a range of serious mental health problems, including schizophrenia”
- “We need a massive programme of public education to convey the danger of cannabis use.”
- “I am announcing today joint work with the Secretary of State for Education and Skills in relation to schools”
- “The council recommends … greater protection for those with pre-existing mental conditions that place them at particular risk from cannabis use”
- “The council recommends … strengthened medical services for those dependent on cannabis”
- “a substantial research programme into the relationship between cannabis and mental health should be instituted”
Three months on...
...no plans have been announced for either:
- a public health education campaign:
i) The UK Government has never instituted a public health education campaign on the mental health effects of cannabis, though the French Government spent €3.8m on a communications campaign in 2005. - nor better drugs education in schools:
i) Current DfES guidance does not cover the mental health effects of cannabis, stating only that “no clear causal link has been proven”.
ii) A previous COI project to deliver information materials for young people is severely underfunded. - nor protection for people with pre-existing mental illness:
i) No information currently exists for this group of people – a COI project to deliver information materials started in 2004, was severely under-funded (only £230,000 was available) and ill-conceived (it relied on health professionals delivering information rather than communicating directly with people with mental illness). It still has not been delivered.
ii) There are currently no specific measures to deter cannabis dealing around mental health facilities, though special measures exist for schools.
nor more investment in treatment for cannabis dependence. - nor further research:
i) None of the growing research on cannabis and psychosis has so far been funded by the UK Government.
Rethink believes that the Government must deliver on these commitments as soon as possible, in particular:
- the public education campaign must be fully funded, on a similar scale to that in France
- the health education campaign should be separate from any campaign promoting legal messages to engage with cannabis users
- people with mental illness must be involved in delivering the education messages aimed at people with mental illness
- young people must be involved in delivering the education messages aimed at young people.
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
A spokesman from the Department of Health - January 2005
What is the link between cannabis use and mental illness?
There is a general consensus that cannabis use worsens psychotic symptoms among people with schizophrenia and people with bipolar affective disorder (manic depression) who experience psychotic symptoms.
A growing body of evidence suggests cannabis may be a causal factor in the development of psychosis. Cannabis is neither a necessary or sufficient cause of psychosis - many people use cannabis and do not develop psychotic symptoms; and many people who have psychotic symptoms have never used cannabis. However, it 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 cannot alone cause pinkness.
Zammit et al (2002) looked at 50,000 Swedish conscripts from 1970 to 1996. Teenage cannabis users doubled their chance of developing schizophrenia. Those who had used cannabis more than 50 times had 6 times the usual risk of developing schizophrenia by 6 times. The authors estimated that 13% of schizophrenia could be averted if all cannabis use were prevented.
Further Dutch, German and New Zealand studies have all found a relationship between regular cannabis use and psychosis, with cannabis users doubling or tripling their risk of psychosis, even after controlling for confounding variables. This population research is underwritten by research on the effects of cannabis on brain chemistry and functioning.
A growing body of evidence suggests cannabis may be a causal factor in the development of psychosis. Cannabis is neither a necessary or sufficient cause of psychosis - many people use cannabis and do not develop psychotic symptoms; and many people who have psychotic symptoms have never used cannabis. However, it 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 cannot alone cause pinkness.
Zammit et al (2002) looked at 50,000 Swedish conscripts from 1970 to 1996. Teenage cannabis users doubled their chance of developing schizophrenia. Those who had used cannabis more than 50 times had 6 times the usual risk of developing schizophrenia by 6 times. The authors estimated that 13% of schizophrenia could be averted if all cannabis use were prevented.
Further Dutch, German and New Zealand studies have all found a relationship between regular cannabis use and psychosis, with cannabis users doubling or tripling their risk of psychosis, even after controlling for confounding variables. This population research is underwritten by research on the effects of cannabis on brain chemistry and functioning.
