Cannabis therapy ‘may be harmful’

Cannabis extracts can be harmful because of the unpredictable way the body reacts, New Scientist said.

Research detailed to the Federation of European Neuroscience Societies found boosting levels of some cannabinoids worsened epilepsy and Alzheimer’s.

Experts said it was hard to target the drug at specific parts of the body.

Some compounds in cannabis interfere with a natural signalling system in the brain, nerves and immune system.

The signalling system, which produces its own cannabinoids, plays a role in conditions such as MS, epilepsy, Alzheimer’s disease, schizophrenia and Parkinson’s disease.

Extra cannabinoids, from smoking cannabis or from medications, can therefore have a significant effect, researchers suggest.

Vincenzo Di Marzo, of Italy’s National Research Council, told the conference that he had found boosting the level of one natural cannabinoid, andandamide, in rats initially appeared to protect the animals from memory loss and nerve degeneration.

But if the rise was prolonged, the cannabinoid could be ineffective, or even damaging.

Beat Lutz, of the University of Mainz in Germany, found a another paradox in models of epilepsy in mice.

The same cannabinoid is normally produced by the body during an epileptic seizure to produce a calming effect.

But he found boosting levels could actually worsen seizures.

Reason

He said he believed the reason for the findings was that there were cannabis receptors on two different types of neuron populations which the drug could affect.

In one group, exposure to cannabinoids increases activity while in the other, it inhibits it.

Dr Lutz said this meant that depending on which one they hit, the effect was different.

Professor David Baker, from University College London, who has studied the impact of cannabis extracts in treating multiple sclerosis, said: “The problem with cannabis is that there’s no way of targeting the drug to any particular place.”

He said the hope was that scientists could manipulate the nervous system by managing the way cannabis compounds are released just as the depression drug Prozac does for serotonin by delaying release.

The only cannabis-based drug which can be used in the UK is a treatment for MS called Sativex.

It has been granted a special licence meaning it can only be used if the doctor takes responsibility for prescribing it.

The drug, produced by GW Pharmaceuticals, is a mouth spray containing two chemicals found in cannabis, THC and cannabidiol.

However, it is made using plant cannabinoids, rather than those found in the body.

Source:BBC.co.uk 27th July

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