New research links cannabis use and psychotic experiences

Cannabis use among students can lead to psychotic experiences, according to new research led by the University of Bath.

Using cannabis has been related to psychotic experiences in the general population but few studies have examined this relationship in undergraduate students despite high levels of cannabis use in this group.

Thomas Richardson from the Mental Health Research & Development Unit, along with colleagues in Dublin, asked 334 undergraduate students in the UK, Ireland, Canada, USA, Australia and New Zealand to complete a questionnaire about their use of cannabis as well as a measure of psychotic symptoms.

The researchers found that those currently using cannabis were more likely to have had hallucinations such as hearing voices that other people cannot hear.

Those who used the drug more frequently were at a greater risk still of experiencing such hallucinations, and heavy use also increased the risk of having delusions such as believing that someone was reading their mind.

Thomas said: “The study found that those currently using cannabis had higher levels of hallucinatory experiences that those who were not using cannabis. More frequent use was related to an increased likelihood of hallucinations, and heavy use also increased the risk of experiencing delusions. This suggests that students who move from occasional, perhaps recreational cannabis use to more regular use are more likely to have psychotic experiences.

“I must stress the limitations of this research, but nonetheless these findings are important as undergraduate students as a population have very high levels of cannabis use. This research suggests that those who use cannabis are more likely to have psychotic experiences, which in the long run may increase the risk of developing a serious mental health problem. These results are therefore important for health professionals who work with students.”