How do cannabis, heroin, morphine and other mind-altering drugs work? The answer came in a dream during the 1970s to Hans Kosterlitz, who worked at the University of Aberdeen. He was more than 70 at the time, thus giving hope to other oldies that their careers, too, might finally come good.

Kosterlitz dreamt that the drugs were not working by novel mechanisms but were simply mimicking the effect of our own, as yet undiscovered, internal chemicals. So to find those chemicals he passed guinea-pig brain extracts over lengths of guinea-pig guts.

Since heroin and morphine not only alter minds but also cause constipation, he soon began to identify the brain chemicals that, morphine-like, immobilised the gut lengths. That is why we call those chemicals endorphins — from “endogenous morphine”, morphine that grows from within.

We also now know that cannabis contains cannabinoids, which mimic the effect of natural brain chemicals we consequently call endocannabinoids. What do they do? In a recent paper in Nature Robert Malenka, of Stanford University, suggested that they act on brain neurons in ways that protect us from Parkinson’s disease.

By using mice that were predisposed to Parkinson’s disease, Malenka showed that when he applied to their brains chemicals that strengthened the effects of endocannabinoids, the mice became resistant to the disease.

Will smoking spliffs à la young David Cameron protect us from Parkinson’s? Perhaps not. The cannabinoids in cannabis are sufficiently different from many of our own endocannabinoids that no one knows if they will cross react in the right way with the key neurones.

But smoking spliffs might — just might — help sufferers from multiple sclerosis. In 2000 David Baker, of the University of London, published a study showing that certain endocannabinoids that appear to relieve the symptoms of multiple sclerosis are sufficiently similar to spliff cannabinoids that a mellow puff might help sufferers. The scientific jury is still out.

But the economic jury is still sitting, because the cannabis story has provided a surprise. We are assured by the farming lobbies that agricultural research, like all scientific research, depends on government grants and the protection of patents. But during recent years cannabis growers have developed increasingly potent, increasingly disease-resistant strains — harvesting the vast cannaboid yields that have now given us skunk — without public money or intellectual property rights and despite government discouragement. Might the stories that research should be dependent on the State therefore not be true? Now that would be mind-altering.

Our politicians proselytise about a world of retirement ages, abstention from drugs and dogmas about the nature of economic development. The real world, however, is advanced by pensioners studying illegal chemicals.

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