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Drugs: Schizophrenia

Volume 684: debated on Monday 24 July 2006

asked Her Majesty's Government:

What assessment has been made of the use of street drugs, including cannabis, acting as triggers of schizophrenia and temporary psychotic symptoms; and what information is made available to primary care trusts and schools warning that cannabis may be one of the factors causing schizophrenia when used in late childhood and early teens.[HL6960]

The Department of Health monitors all the key research in cannabis misuse and has a range of expert advisers to inform policy. We are currently commissioning an academic “expert topic review” of research on cannabis and mental health, with the aim that its findings will inform mental health promotion regarding cannabis, and will help us to ensure that our advice to mental health patients, their families and professionals continues to be comprehensive and up-to-date.

The Advisory Council for the Misuse of Drugs (ACMD) report on cannabis, Further consideration of the classification of cannabis under the Misuse of Drugs Act 1971 (2005) reviews the evidence on the mental health effects of cannabis. The report states that ACMD remains of the view that cannabis is harmful and its consumption can lead to a wide range of physical and psychological hazards. Nevertheless, it does not recommend that the classification of cannabis products should be changed on the basis of the results of recent research into the effects on the development of mental illness. Although cannabis is unquestionably harmful, its harmfulness does not equate to that of class B substances at the level either of the individual or of society. The department also published independent advice on the health harms, including mental health harms, of a range of substances in its guidance in September 2003, Dangerousness of Drugs—A Guide to the Risks and Harms associated with Substance Misuse.

In 2004 the Government produced guidance to schools on all matters relating to drug education. This has recently been updated to specifically highlight the dangers that cannabis use can lead to a wide range of physical and psychological problems. In addition, the key stage 3 drug education pack, due to be published imminently, also highlights the possible links, both in the pupil and teacher versions.

The department has developed three new leaflets for the Government communications campaign FRANK ( on cannabis: for young people, for heavy users and for parents. All give information on the possible side effects of cannabis use.

The department has specifically made information available to primary care trusts about the regular and early use of cannabis possibly causing an increase in an individual's risk of developing “psychotic symptoms” including schizophrenia.