August 27, 2025

expert reaction to two studies on cannabis: one looking at reasons for first use cannabis and association with subsequent THC intake and symptoms of paranoia, anxiety or depression and one looking at childhood trauma, paranoia and cannabis use

Two studies published in BMJ Mental Health and Psychological Medicine looks at first use cannabis and mental health outcomes, childhood trauma, paranoia and cannabis use. 

Dr Emily Finch, Chair of the Royal College of Psychiatrists’ Addiction Faculty, said:

“These important findings reinforce previous work which suggests that cannabis can have significant adverse effects on users’ mental health.  Society must be more aware of the substantial evidence on cannabis harms, and correct the widespread misapprehension that cannabis is not an addictive substance.

“Cannabis is the most widely used illicit substance in the UK, and around a third of people who use cannabis develop a problem with the drug at some point during their lives.  This is similar to the proportion of people who will develop a problem with alcohol.

“The use of both natural and ‘synthetic’ cannabinoids over the long-term risks addiction and severe co-occurring mental illness harms.  Daily cannabis use is associated with depression, anxiety and reduced motivation.

“Daily users of high-potency cannabis are nearly five-times more likely to develop a psychotic disorder than people who have never used cannabis, with adolescents at particular risk.

“As a priority, the UK Government must provide substance use and mental health services with the training, staff, and funding they need to support people with co-occurring substance use and mental illness.  This must also include a focus on providing early treatment to the increasing number of children and young people struggling with substance misuse if we are to reduce long-term harms.”

‘Are reasons for first using cannabis associated with subsequent cannabis consumption (standard THC units) and psychopathology?’ by Edoardo Spinazzola first author et al. was published in BMJ Mental Health at 01:01 UK time on Wednesday 27 August 2025. 

‘The impact of childhood trauma and cannabis use on paranoia: a structural equation model approach’ by Giulia Trotta et al. will be published in Psychological Medicine at 01:01 UK time on Wednesday 27 August 2025. 

DOI: 10.1017/S0033291725101190

Declared interests

Dr Emily Finch: “No conflicts of interest.”

This Roundup was accompanied by an SMC Briefing.