Dr. Philip Dodd:

Yes. First, this is an important issue to raise in the context of a mental health discussion, be it in respect of young people, children, adults or the general population. The association of the use of cannabis with the subsequent development of mental health problems is well established. I will not go into the technical aspects of the literature but a recent comprehensive publication aligned the use of cannabis with the subsequent development of psychosis, depression, self-harm and suicide. That link is very strong so any discussion on the liberalisation of cannabis must be very much aware of the experience in other countries of the impact it has had on presentations. In Ireland, after psychoactive substances that were available in head shops were restricted, a number of Irish research studies, including research from our national self-harm database, showed that the level of psychiatric admissions reduced.

The prevalence of relevant associated self-harm also dropped. Society must always be aware of the unintended or intended consequences of the liberalisation of what are psychoactive substances. In the same way, we know alcohol is associated with up to one third of self-harm presentations across our emergency departments.