People who smoke strong strains of cannabis are at greater risk of memory loss than those who smoke other types of the drug, according to new research.
Experts writing in the British Journal of Psychiatry called for cannabis users to be made aware of the risks associated with some strains of cannabis, and encouraged to use varieties with higher levels of the extract cannabidiol instead.
Cannabidiol and THC are two major constituents of cannabis. THC is the main psychoactive ingredient that makes users feel "stoned", and produces psychotic-like symptoms such as delusions and paranoia.
In contrast, cannabidiol does not induce these symptoms and may counteract the effects of THC. Levels of cannabidiol in cannabis can range from almost none to up to 40 per cent.
University College London researchers found that people smoking cannabis with a low cannabidiol content performed much worse on memory tests when they were intoxicated. In contrast, those smoking cannabis high in cannabidiol performed just as well on the tests when they were intoxicated.
By Lyndsay Moss
01 October 2010