A study in the US has shown cannabis can reduce symptoms of post-traumatic stress disorder (PTSD) by more than 50 per cent.

According to the findings, recently published in the Journal of Affective Disorders, cannabis temporarily reduced the severity of memories of a traumatic event by around 62%, flashbacks by 51%, irritability by 67 and anxiety by 57%.

Washington State University assistant professor of psychology Carrie Cuttler analyzed a self-selected sample of more than 400 people who tracked changes in their PTSD symptoms before and after cannabis use via an app, giving 11,000 data points over 31 months.

Cuttler said: “The study suggests cannabis does reduce symptoms of PTSD acutely, but it might not have longer term beneficial effects on the underlying condition. Working with this model, it seems that cannabis will temporarily mask symptoms, acting as a bit of a band aid, but once the period of intoxication wears off, the symptoms can return.”

The levels of THC and CBD in the cannabis products used by participants made no difference to the outcomes, according to Cuttler.

She added: “We need more studies that look at whole plant cannabis because this is what people are using much more than the synthetic cannabinoids. It is difficult to do good placebo-controlled trials with whole plant cannabis, but they’re still really needed.”