Whether the use of cannabis, alcohol or amphetamines leads to psychosis or whether, on the contrary, it is psychosis that leads to the use of these drugs, is one of the great dilemmas of psychiatry. The psychiatrist José A. Posada Villa reveals an investigation that could clarify the matter.
There has been much discussion about the relationship between the use of psychoactive substances and psychosis, especially now that there is growing tolerance for the use of cannabis on the part of governments and society in general.
The most common problem linking mental disorders and substance use is the intention of people seeking to alleviate annoying or uncomfortable mental symptoms. Some examples include the person with depression who uses marijuana to feel better, the individual who suffers from social anxiety and drinks to feel more comfortable in situations involving interaction with others, the one who fights panic attacks and takes anxiolytics to calm symptoms or stop attacks before they start or the one who feels low energy and lack of motivation and uses cocaine or amphetamines to increase mood.
A psychotic experience is described as loss of contact with reality, usually with delusions and hallucinations. For some time now there has been scientific evidence that between 5 and 10% of the general population presents at some time alterations of sensoperception (hallucinations) and thought (delusions) without necessarily evolving to a true psychosis in psychiatric terms. In this context, the difference can be made between having a psychotic experience and suffering from schizophrenia, having sadness and suffering from a major depressive disorder.
There are two hypotheses. The first is that substance use triggers psychotic symptoms in those with an underlying genetic predisposition, and the second is that exposure to substance use is sufficient in itself to lead to psychosis, independent of that predisposition. The dominant position to date has been that substance use triggers psychosis.
The May edition of the Addiction Journal, one of the most renowned international scientific journals on the subject, has just presented new data that we have generated with colleagues from the WHO World Mental Health Survey, Harvard University and the University of Michigan, on the complex relationship between psychosis and consumption of psychoactive substances, which seeks to identify whether the consumption of these substances leads to psychosis or on the contrary, it is psychosis that leads to consumption, a question of great importance for prevention and rehabilitation programs.
In a representative sample of the general population, composed of 30,902 adults surveyed in 18 countries with different levels of development, including Colombia, it was first found that the consumption of alcohol, tobacco and controlled drugs taken without medical indication, predicts the subsequent presence of psychosis. But the story does not end there. According to the same research, both alcohol and tobacco consumption predict a two-way effect in relation to psychosis. In other words, it is observed that, while alcohol and tobacco consumption predict the onset of psychosis, it is also found that psychosis leads to later consumption of alcohol and tobacco.
But perhaps most notable of the findings of the study is that it was found that psychotic experience predicts later use of marijuana, but that the use of this substance does not predict subsequent psychotic experience. This goes against many publications that support the relationship between cannabis use and psychosis.
This new scientific evidence departs from the simplistic perception that the consumption of this type of substance inexorably leads to psychosis, as the available evidence shows bidirectional effects.
The research also raises other questions, as people with psychosis use cannabis as a form of self-medication for distressing symptoms. In this sense, it is worth mentioning recent publications on the first trial of treatment of schizophrenia with cannabidiol, the component of marijuana that currently has more therapeutic uses, which shows a (modest) benefit in reducing psychotic symptoms.
It is difficult to determine whether people in whom the initial symptoms of psychosis appear medicate themselves or rather use psychoactive substances because of their personality traits or lifestyle changes related to the onset of the mental disorder.
Some researchers have suggested that individuals in whom psychosis has a substance-related onset suffer a distinct subtype of psychotic disorder. Drug-induced psychosis is still considered a distinct diagnostic category from psychotic disorders of a strictly psychiatric nature, since in the former, symptoms decrease when substance use is discontinued, while in the latter, symptoms persist.
While the vast majority of people who smoke cannabis do not develop psychotic disorders, unfortunately psychoactive substances and alcohol contribute little to managing the underlying mental symptoms and may ultimately lead to new problems or increase the severity of other mental symptoms.
In conclusion, it can be said that the association between psychosis and substance use disorders is often bi-directional, but not all types of use are associated with psychosis.
For now, the challenge for researchers is to find conclusive answers to these questions and to find a practical and honest way to communicate this information to governments and citizens.