Cannabis Use Increases Risk of Developing Psychosis, Priory Experts Warn

Posted on by Adina Rees

Cannabis is the most commonly used drug in the UK, with 7.2% of adults aged 16-59 admitting to smoking it in the last year, according to the Home Office Crime Survey. A recent poll by The Independent found that 51% of Britons supported decriminalisation of marijuana, and young adults are more likely to be in favour of this than older generations. However, many who oppose this legalisation have expressed fears over the drug’s long-term impact on mental health.

A study, conducted by Theresa Moore and Stanley Zammit, found that whose who have used cannabis at least once in their lifetimes have a 41% higher chance of developing psychosis than those who haven’t. Similarly, regular cannabis users are over twice as likely to develop a mental illness as those who abstained. Young cannabis users in particular risk developing a psychotic illness, such as schizophrenia, due to the drug’s effects on their still-developing brain.

Priory Healthcare conducted a similar study very recently, and their results corroborate Moore and Zammit’s finding. The Priory Group is the leading provider of behavioural care in the UK, caring for more than 30,000 people with mental illness and addictions. 

Dr Niall Campbell, a consultant psychiatrist at Priory’s Roehampton hospital, stated that 25% of their paranoid psychosis cases are associated with cannabis use. He warned that the chemicals found within marijuana are “up to 100 times stronger than substances in the 1960s”. Tetrahydrocannabinols (THCs) are the primary psychoactive part of cannabis, and these may trigger temporary schizophrenic-like symptoms.

Figures show that cannabis caused more than 125,000 NHS admissions in the last five years; 15,000 of these cases involved teenagers, some of whom had experienced serious psychosis. Although many consider adolescence to end at 18, the brain still undergoes critical development until we are around 25 – the risk of cannabis interfering with mental health is particularly strong during this developmental phase.

One study in the American Journal of Psychiatry followed over 3,800 teenagers for four years. The teenagers reported their marijuana and alcohol use and completed cognitive tests over time to track any possible decline. The study found that cannabis use impacted the teenagers’ long-term memory more than alcohol consumption, and this change in brain function did not recover even after students stopped using cannabis.

The movement for the legalisation of cannabis has seen strong support from many public figures, both academic and celebrity. However, with new research highlighting the often under-reported side effects of the drug, many academics are urging the general public to reconsider if its benefits truly outweigh its risks.

Adina Rees

Image: [Pixabay]