Cannabis is associated with psychosis (a symptom) and schizophrenia (an illness where this symptom is persistent) in complex, contradictory and mysterious ways. The evidence does demonstrate various links that we all should all be aware of, especially cannabis users and parents. However, the evidence does not support anything like the level of fear propagated in the media.
Thanks in part to the Netherlands' policy of marijuana decriminalization, there are people living in the Dutch city of Utrecht whose addiction to cannabis prevents them from getting effective treatment for mental illness. According to a September 10 statement from Utrecht Mayor Wolfsen, "There is a group of about eighty people with a chronic psychotic disorder who barely respond to their treatment. A possible explanation for this is their severe dependence [on] cannabis."
New research finds that the two main ingredients in marijuana have opposing effects on it. The study examined 15 normal men who had previously smoked cannabis only a few times. Researchers exposed the men to each of the two most psychoactive ingredients in marijuana — delta-9 tetrahydrocannabinol (THC) and cannabidiol (CBD) and compared their effects with those of a placebo while the participants performed a mental task.
That cannabis and schizophrenia are linked is widely accepted. Several studies suggest the drug can set off short-term psychotic episodes in those already suffering from the condition. Other research, though, does more than this. It shows that people with schizophrenia are twice as likely as others to use cannabis. This leads some to argue that the drug is actually a cause of schizophrenia rather than just a trigger—a line of evidence sometimes employed by those who wish to keep it illegal.
A compound found in marijuana can treat schizophrenia as effectively as antipsychotic medications, with far fewer side effects, according to a preliminary clinical trial. Unlike the main ingredient in marijuana, THC, which can produce psychotic reactions and may worsen schizophrenia, cannabidiol (CBD) has antipsychotic effects, according to previous research in both animals and humans.
Marijuana has been shown to have both anxiolytic (anti-anxiety) effects and to induce anxiety and psychosis in certain people. In schizophrenics, it can increase symptoms, and in healthy people it can increase the risk of schizophrenia. Now, new study shows that the two active ingredients in pot, Δ9-tetrahydrocannabinol (THC) and cannabidiol (CBD) may have quite opposite effects on the brain – and behavior – and could explain why pot’s effects can be unpredictable.
Dr David Potter and GW Pharmaceuticals – a company that is exploring how cannabis could help treat a range of illnesses ranging from epilepsy to cancer – have turned their attention to developing a cannabis-based treatment for psychosis and related illnesses such as schizophrenia. For a drug that is widely seen as a trigger for acute psychotic illness in young users, this at first sounds preposterous. But, as Potter explains, the cannabis plant is much more than just a psychedelic weed. A cannabinoid known as CBD (or cannabidiol) appears to have almost the exact opposite effect.