Julie Lynn-Evans: Legalise the old stuff but make the new stuff a class A drug

The evidence is coming in thick and fast. Yesterday came news of yet another survey showing the damage cannabis does to young lives. A study published in the journal Addiction says that by the end of the decade one in four of new cases of schizophrenia could be triggered by smoking cannabis.

I work in London as a child psychotherapist, and the facts at the coal face leave me with very little doubt. The "old" type of cannabis that used to be available in the 1960s and 1970s is worlds apart from much of the stuff that is easily acquired nowadays. People will argue about the precise difference in strength (the amount of tetrahydrocannabinol - THC), but, indisputably, skunk is often 15 times stronger than that which used to be available. If I had my way I would legalise the old stuff and make skunk a class A drug.

To anyone who sees what goes on in courts, in hospitals, in hostels for the homeless, and in the faces of the children who have been smoking too much, the influence of skunk is clear. When a new case of a psychotic young person comes to me, the chances are that skunk has played a part in their troubles.

In an age when children grow up frighteningly quickly, it is easy to forget that the brains of teenagers are nothing like fully formed. Scientists used to think that the brain was mature at the age of 18. Nowadays the belief is that it happens at around 21. Up until then, youngsters, particularly males, struggle to make sense of the world. The Kevins, of Harry Enfield fame, are only a slight exaggeration. Teenagers, by their very nature, lack responsibility and are extremely sensitive. So if a THC-rich drug is inflicted on immature frontal lobes, their neural pathways can be badly distorted. This is not about a drug that makes you feel a bit woozy and then passes. It is doing physical violence to one of the body's most sensitive parts.

What makes it worse still - which few defenders of cannabis use are prepared to take on board - is that precious little is known about how to treat these young brains when they hit real trouble. We have a rough idea how to treat anorexia, we are coming to understand self-harm, there are established treatments for addressing cocaine addiction. But we know next to nothing about skunk-induced psychosis. Adolescents gripped by psychosis can reach a point of no return. We can tank them up with heavy anti-psychotic medication to prevent them having hallucinations and hearing voices, but it is far from ideal if they stay on such strong medication. After that, we are virtually stuck for answers. Those who see skunk as being "like the stuff we used to smoke, only a bit stronger" would do well to remember that.

Does skunk actually cause psychosis or simply act as a catalyst to those with a psychotic predisposition (or, as some claim, does it have no link at all)? My own view - a hunch based on 20 years in the field - is that there is some sort of link between psychosis and the increases we have been witnessing in learning difficulties, such as dyslexia, dyspraxia, right on up to Asperger's syndrome. Research shows that one in five boys and one in seven girls now have some such problem. My guess is that it is those with a disposition towards one of those disabilities who will be prone to suffer most from skunk's ill-effects. And it is precisely those people for whom life may be trickiest, who may feel the greatest need of some sort of self-medication with the stuff. If you see lawless groups of young kids in the street or teenagers who threaten passers-by with knives, there is a strong chance that they have used skunk in the previous 24 hours. I am not saying that skunk has caused the lawlessness, but it definitely won't have helped. If you see a sheet-white young person who looks lost and mentally ill, then the same is probably true.

If an amiable, middle-aged, would-be hippy tells you that the odd spliff never did them no harm, they are probably right. But the world has moved on.

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