Governments come down hard on it. There is a case against marijuana, but it is not a watertight one.
Last week the UK home secretary sacked his government’s chief scientific advisor on drugs, Professor David Nutt, the very day after King’s College London published a lecture in which Nutt had claimed that tobacco and alcohol were more harmful than some illegal drugs, including ecstasy, LSD — and marijuana.
This flew in the face of the government, which had recently raised marijuana into “Class B” of its drugs schedule, from Class C. In Class B marijuana sits alongside other psychotropic drugs like amphetamines and barbiturates. Psychotropic substances act on the central nervous system — that is, they affect brain function, and impact mood, awareness and behaviour.
Nutt argued that marijuana should remain in Class C. According to him, its classification as dangerous and the criminal penalties applied were choices made for political rather than scientific reasons. In a “drug harm ranking” published by a colleague of Nutt’s in 2007, cannabis, from which marijuana is made, was ranked 11 of 20 harmful drugs. Alcohol was fifth, and tobacco ninth (heroin and cocaine headed the list). The paper said the official “classification excludes the psychoactive drugs whose use causes the greatest harm”, that is, alcohol and tobacco. In his own lecture, Nutt asked, “Don’t we need to compare harms to determine if [marijuana] should be illegal?”
Scientific opinion is not unanimous on the health threat posed by marijuana. It is generally considered true, however, that marijuana is not chemically addictive, cannot be overdosed on, has limited side-effects, does not result in extreme disruptive behaviour, may actually help people suffering from certain conditions, and is good at alleviating pain and stress in those undergoing harsh treatments for cancer and AIDS. In the Netherlands it is legal, and in California it can even be medically prescribed.
“The medical literature indicates that the big risk is probably for people with a vulnerability for psychosis, like schizophrenia,” says Dr Mahesh Menon of the Centre for Addiction and Mental Health in Toronto, Canada, “where it increases your odds of transitioning into the illness. And it can cause exacerbation of symptoms in people prone to experiencing paranoia and hallucinations.” He goes on, “I know a few folks who do it too much, and meet criteria for addiction. It does seem to sap them of their motivation to do pretty much anything.”
He makes a distinction between substance abuse and dependence: “With marijuana all we can say is that there isn’t physiological dependence. You won’t have withdrawal symptoms if you don’t smoke every morning, but there might be some component of psychological dependence, and there is much potential for abuse. I know people who have experienced some withdrawal symptoms — typically irritability, some increases in anxiety, low mood, insomnia... These might be to do with the potency of the marijuana available, or possibly a mixture of physiological and psychological factors, and driven largely by the latter.”
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It is easy enough to find user experiences. “I did like the ‘slowing down’ of things, thoughts, sensations,” says one former user who prefers to remain nameless. “It felt like I had more time to savour the small parts of the experience. But I also felt slow the next day, and I didn’t like the numbing, tingly physical sensations I sometimes had on my fingers and toes.”
“Everything becomes pleasant and warm and fuzzy,” says another former user. “You lose a critical sense of things. You cannot judge the facts.”
“I hate going out,” says a current user, lighting up his sixth joint of the day. Has it had any negative effects? “Not that I can think of.” But a friend of his says it has. “It has turned him into a recluse. The only time he gets out is to get his share of weed, and yes, it has slowed down his senses. You can make that out very easily by the way he talks, walks and moves around his room. And there are times when he is extremely anxious.”
Most marijuana users come to it in their adolescence, when they are too young to drink legally. Studies have shown that the drug has a significant impact on the adolescent brain, especially affecting those areas of the brain which control higher-level thinking and language development. The effect on the brain is similar to that seen in schizophrenics.
At the same time, there is growing anecdotal evidence that in some medical cases marijuana can be useful rather than harmful. It boosts appetite (recreational users call it “the munchies”), has an anti-nausea and sleep-promoting effect, and helps a user relax. Because of the number of natural cannabinoids — the active chemicals — in marijuana, it is more effective as a calming agent and painkiller for patients undergoing harsh treatments than engineered cannabinoids. A few autistic or epileptic patients on whom no other treatment has worked have also seen improvement with the use of vapourised marijuana.
If potential schizophrenics are the most at-risk section of marijuana users, and the other negative effects are muted or slow to manifest, perhaps Nutt was right to make the point he did. Habitual tobacco and alcohol use results in known, measurable and cumulative damage to users as well as to society. There is a case against marijuana, but it is not a watertight one.