One of the important policy drivers when the Labour government were considering reclassifying cannabis the last time was the links being made between cannabis use and mental health problems.
At the time it wasn’t clear whether these links were causal, or how extensive the risk might be, but there was enough evidence for mental health campaigners to make this an issue and to make Ministers wary about leaving the drug at Class C despite the advice they received from the ACMD.
What this new Dutch research suggests is that there is a bi-directional causal association – ie that using cannabis can cause mental health problems, and that having mental health problems in the teenage years can lead to people using cannabis.
Significant associations (r=.12-.23) were observed between psychosis vulnerability and cannabis use at all assessments. Also, cannabis use at age 16 predicted psychosis vulnerability at age 19 (z=2.6, p<.05). Furthermore, psychosis vulnerability at ages 13 (z=2.0, p<.05) and 16 (z=3.0, p<.05) predicted cannabis use at, respectively, ages 16 and 19.
From our point of view this ties in with a presentation I gave to a room full of school people as part of a conference on mental health. As you’ll see I’ve adapted parts of Claire’s wonderful presentation about what works in drug education and added specific stuff about mental health.