Marijuana hope for epileptics

By STEVE CONNOR

Marijuana could help to prevent epilepsy in some patients, says a study showing that natural cannabis-like substances in the brain can calm overactive nerves.

The findings suggest it may be possible to stimulate the body's own innate cannabinoids - the active ingredients of cannabis - to control epileptic seizures caused by hyperactive brain cells.

Although the research has been done in animals, scientists believe the discovery could lead to clinical trials in humans to augment cannabis trials already under way in Britain studying its pain-relieving properties.

Beat Lutz, of the Max Planck Institute of Psychiatry in Munich, said the study showed the brain's natural cannabis system was involved in preventing epileptic seizures.

"When the brain's nerve cells begin to fire too much, then there is a huge production of innate cannabinoids which calms everything down," Dr Lutz said.

Anecdotal accounts of cannabis being used to control epileptic fits go back many centuries.

Ibn al-Badri, an Arab writer of the 15th century, described how cannabis was used to cure the epileptic son of a caliphate council member.

In the 19th century, at least one British doctor working in India used hashish to treat a patient's convulsions and in the 1970s, medical researchers investigated the anti-epileptic activity of cannabis more scientifically.

The latest research, published in the journal Science, has concentrated on the role played by the brain's innate cannabis system - protein receptors on the surface of nerve cells that bind like a lock and key to naturally produce cannabinoids.

When the scientists produced genetically engineered mice lacking the proteins - called CB1 receptors - they found that the animals suffered excessive epileptic seizures.

Furthermore, the researchers were able to identify which parts of the brain the CB1 receptors work best in, preventing fits by calming down overactive nerve cells.

But Dr Lutz warned that giving cannabis to epileptic patients to simulate the body's innate defence against seizures might work for only some people and make matters worse for others. It would be better to develop drugs to target indigenous cannabinoids.

"It is a self-defence system and is only active when it is needed. You don't have it active all the time, so flooding the brain all the time with cannabis may not be a good thing."



Leslie Iversen, visiting professor of pharmacology at Oxford University and a world authority on cannabis, said the latest research appeared to explain why the brain produces its own cannabis-like substances.

"It's a very beautifully done piece of work and provides another insight into the role of the naturally occurring cannabis system in the brain," he said.

"The research pinpoints the very interesting role of natural cannabinoids in damping down the hyperstimulation of the brain."

Of the 60 known chemicals in cannabis, the most active is tetrahydrocannabinol (THC). The Medical Research Council in Britain has begun cannabis THC trials for pain relief after surgery and in multiple sclerosis.

Cannabis and epilepsy

Scientists found the brain's own natural cannabis system produces a calming effect which protects against epileptic seizures.

But they warn that "flooding the brain" with cannabis itself may not be the best solution for epileptics.

A new drug which stimulates the same receptors in the brain could be the answer.

- INDEPENDENT