Smoking cannabis which has previously been shown to damage mental health, now according to a new study may be useful in relieving the symptoms of severe mental illnesses such as bipolar disorder.
The drug has in the past been linked to an increased risk of developing such conditions, but a team from the University of Newcastle upon Tyne, Newcastle upon Tyne say chemicals found in cannabis could be used to relieve the symptoms of those very same illnesses.
The Newcastle researchers had anecdotal reports from people with mental illnesses which suggested cannabis could alleviate symptoms, and the scientists have been trying to find ways of harnessing the beneficial aspects of the drug without exposing people to the harmful ones.
The team reviewed research carried out into the properties of cannabis and they found evidence that two chemicals in cannabis could aid people with mental illness; THC (tetrahydrocannabinol) and CBD (cannabidiol).
THC helps give the 'high' associated with cannabis use, while CBD has been found to have calming properties.
The team say combined together they could help people with bi-polar disorder avoid the manic highs and depressed lows of their condition.
But they warned smoking the drug had been shown to cause long-term damage to mental health, and to increase the risk of mental illness in those who were already genetically susceptible.
They feel trials should now be carried out to see if the combination of chemicals does help people.
They are hoping to use a mouth spray created by GW Pharmaceuticals containing THC and CBD, which has been licensed for use for pain relief in Canada, as soon as it is licensed in the UK.
The company is already involved in research looking at whether cannabinoids can relive pain symptoms for people with diseases such as multiple sclerosis.
Heather Ashton, professor of clinical psychopharmacology, who led the study, says by using this mixture in the right dose and the right proportions, it may be possible to help people with bipolar disorder, whatever way they are veering and it might be useful to patients to try a known mixture of certain cannabinoids, as an additional drug rather than as a single drug.
She adds that people who take cannabis for relief of these symptoms do not need the heavy doses that recreational users take.
Professor Ashton does caution that it is agreed that smoking cannabis, especially when young, in large quantities, is associated with mental illness, and is quite different from using it medicinally.
Jane Harris, campaigns officer at the mental health charity Rethink says that although cannabinoids are an exciting new area for medical research, but it is important to recognise that there are over 60 active ingredients in cannabis and the two mentioned in the study may only help in the treatment of bipolar disorder when taken in controlled doses.
Mental health campaigners called for further work to confirm this, and for most people with severe mental illness, raw cannabis remains a risky substance
In January this year, the government announced a review of all academic and clinical studies linking cannabis use to mental health problems.
The study is published in the Journal of Psychopharmacology.