Rufus May: I smoked cannabis. I went mad. But life's not that simple

As the review published in The Lancet last week confirmed, studies have been finding an association between cannabis and psychotic experiences for the past 30 years. The reviewers looked at 35 studies and suggested that cannabis users have a 40 per cent increased chance of having psychotic experiences. They also say that 14 per cent of psychotic problems in the United Kingdom could be linked to cannabis use. But not all the evidence supports a simplistic causal link. For example, while the use of cannabis has gone up steadily over the past 30 years, the incidence of psychotic diagnoses has not. Yet the research coming out of the Institute of Psychiatry and this latest review from Bristol and Cardiff universities is putting growing pressure on the Government to reconsider its classification of cannabis as a class C drug.

Cause and effect are difficult to unravel. Are people with a tendency to hear voices or suffer from paranoia attracted to using cannabis to calm themselves or is the drug increasing the risk of these experiences? Perhaps both processes are happening. In my experience, both as a user and as a psychologist, cannabis can be both a tonic and a poison. Ultimately, like all drugs, it brings problems, but demonising it will not help.

At the age of 15 and 16 I smoked cannabis pretty heavily. It helped me escape the boredom of school life and fractious relations with my parents. It also helped me bury deeper anxieties about impending adulthood and my identity. I fell in love with the idea that this illicit weed could bring me serenity on a daily basis. Its forbidden status made me feel rebellious and cool. I became addicted to the ceremonious ritual of sticking the papers together and building the spliff that I hoped would transport my mind to a more peaceful place. But life has taught me that if you suppress things sooner or later they come back to haunt you. By the age of 18, I was drug free, trying to get over my first girlfriend leaving me and struggling to find a decent job. Instead of getting depressed, I slowly drifted into a dreamlike reality where I was spied upon and felt I had special spiritual powers. It culminated in being treated psychiatrically for a year and being given the rather unhelpful tag of schizophrenic. My recovery has involved largely steering clear of cannabis and finding more healthy ways to relax and stay calm and centred.

In my work, I help others who have developed psychotic experiences. Many of us choose to avoid using cannabis, but some feel it is helpful in dealing with anxiety and the side effects of the medication they are prescribed. My impression is that some people – and I would include myself in this category – do have a particular sensitivity to cannabis and need to be cautious with it. But I also feel there is a political agenda behind the current "blame the weed for mental illness" campaign. Psychiatrists such as Robin Murray and others spent many years in the 1990s – described as "the decade of the brain" – trying to find a biological and genetic cause for psychosis, but with little success. The latest focus on cannabis can be viewed as the dying gasp of the "blame the brain" brigade who seek to justify a biological approach to madness.

Such an emphasis on chemical causes suits the pharmaceutical industry and obscures the bigger truth that mental distress is caused by emotional traumas and troubles. People who react badly to cannabis but continue to use it are trying to suppress feelings such as anger, guilt and loneliness. It is the social situations that lie behind these emotions that we really need to understand and address.

Rufus May, a clinical psychologist, works with Bradford's Assertive Outreach team