Dr. Elaine Breslin:

Deputy Durkan asked about the side effects. This is an important area because in many of the countries we have referred to where there are broader access programmes - the Netherlands, Czech Republic and Italy - cannabis is not considered a medicine and, therefore, its side effects are not collected in the same way we collect side effects for conventional medicines. Part of our role is to collect the side effects. That is quite different and, in many cases, the establishment of those broader programmes is outside the remit of the regulatory authorities such as ourselves; they are based in the Ministry of health.

The perception of cannabis is quite different. It is not seen as a medicine but as something else. Formal data are therefore not collected.

We have data on use in recreational circumstances. There are many pieces of literature about that. The safety in short-term use is quite well known. The side-effects associated with short-term use of cannabis include euphoria, hallucinations, anxiety, paranoia, psychosis, impaired short term memory and confusion, impaired motor co-ordination, altered judgement and increased risky behaviour. There are some gastro-intestinal side-effects such as diarrhoea. The effects of long-term use, either recreational or heavy use, are of interest. We are aware that there is addiction in 9% of cases. The addiction rate rises to approximately 17% if one begins to use cannabis in adolescence. If one uses it regularly or is a heavy user, the addiction rate rises to about 50%. There is an increased risk of chronic psychotic disorders such as schizophrenia, particularly in adolescence and in people who are at risk because of a strong family history of psychosis. We do not know that cannabis causes psychosis. The literature is not saying that, but it says clearly that cannabis is a preventable risk factor for psychosis. It is a particular risk for young people who have a family history of psychosis and who use cannabis that is associated with a higher level of tetrahydrocannabinol, THC, which is the psychotogenic component of cannabis.

Another risk associated with long term use is cognitive impairment. This is important if it is used in young people in adolescence. There is a potential for cannabis to affect neuro-development and cause neuro-developmental delay. We see cognitive impairment in older people, with lower intelligence quotient, IQ, among those who are frequent users during adolescence. I have referred to altered brain development. It is also associated with poor educational outcomes, increased likelihood of dropping out of schools, a diminished life satisfaction with achievement and what is referred to as the amotivational syndrome. It is also associated with increased risk of suicidal ideation and attempts and with the symptoms of chronic bronchitis. All of those side effects are really associated with recreational use. We do not have good data on the medical use of cannabis.