Extracts from cannabis could help reduce brain damage in stroke victims, according to new research from the American National Institute of Health. NIH scientists have found that several of the cannabinoids are potent antioxidants, and may thus help to prevent damage to brain tissue. In particular cannabidiol, which is non-psychoactive, was found to perform better than other antioxidants.

A stroke happens when a blood clot blocks the supply of blood to the brain. Recent research has shown that most of the damage to the brain after a stroke is not directly caused by the lack of oxygen but by the release of oxidising agents which destroy cells as if they were being burnt. Scientists hope that by blocking the action of these 'free radicals' they can reduce brain damage after strokes, and possibly to slow up the progress of Alzheimers disease and Parkinsons disease. Perhaps brain damage after heart attacks may be helped as well.

The study was carried out at a National Institute of Mental Health Laboratory in Maryland by Dr Aidan Hampson and collegues and reported in the July 7 issue of Proceedings of the National Academy of Sciences. Rat brain cells were grown in a culture and subjected to toxic free radicals. It was found that cannabinoids protected the cells from damage. Cannabidiol performed better than vitamins C and E and as well as the potent antioxidant BHT.

The psychoactive ingredient in cannabis (THC) also protected the cells, but the scientists ruled it out because of its side effects. "Cannabidiol is a desirable candidate for a side-effect-free therapeutic agent because it does not produce euphoria." explained Hampson.

Studies are now underway using cannabidiol in live animals. "Preliminary results are looking promising", said Hampson, noting that the substance passes readily from the blood into the brain and in the past has been tested in humans over several weeks, at high doses, with no apparent side effects reported.

The scientists also ruled out smoking cannabis after a stroke, since they thought it unlikely that enough cannabinoids would reach the brain. Instead it is likely that future patients would take the drug using an inhaler of the type used by asthma sufferers.