Cannabis

Lisa Cameron Excerpts

Monday 12th October 2015 Westminster Hall

[Dr Lisa Cameron (East Kilbride, Strathaven and Lesmahagow) (SNP)]

I thank the hon. Member for Newport West (Paul Flynn) for securing this debate today. It is an extremely important debate, which has been brought forward in response to an overwhelming petition by the public.

Cannabis is the most widely used illegal drug in the UK. Although it appears that there has been a steady reduction in its use since 1996, between 2013 and 2014 about 2.3 million 16 to 59-year-olds reported using cannabis. Frequent use of cannabis is also about twice as likely among young people, with nearly 5.3 million 16 to 24-year-olds reporting having used it during the same time period.

Despite Government and media warnings about health risks, many people see cannabis as a harmless substance that helps them to relax, and as a drug that, unlike alcohol or cigarettes, might even be good for their physical and mental health. Proponents for decriminalisation have also highlighted the potential medicinal properties of cannabis, and argued that legalising the production, supply and use of cannabis would also have a number of benefits for society as a whole. We have heard many of these arguments today.

Transform, a charitable think-tank that campaigns for the legal regulation of drugs both in the UK and internationally, argues that the current approach of prohibition is failing and will never be successful in protecting individuals or society from the misuse of drugs. It highlights that the unintended consequence of prohibition is that it creates an illicit market, which allows the drugs trade to be monopolised by organised crime factions.

A number of my constituents who feel extremely strongly about this issue have contacted me in the run-up to this debate. One of them, Paul, who wished to be mentioned today, supports a motion to decriminalise cannabis due to its medicinal properties, and he has told me that he feels that criminalising a substance produced from organic matter and that holds medicinal potential while allowing “over the counter” sale of many more harmful substances could be viewed as disproportionate, as could driving someone to use the black market to gain hope or relief from a medical condition, such as multiple sclerosis, because nothing else offers the same relief.

On the other hand, medical bodies have reported evidence indicating the significant potential harm that can be caused by cannabis. I am a clinical psychologist who specialised in addiction and forensic populations in my previous career, so the impact of cannabis on mental health is of particular interest to me. Literature published by the Royal College of Psychiatrists in 2014 has highlighted several issues of concern in this regard. While it is acknowledged that not everyone who uses cannabis will develop mental health problems, even among those in the groups in society identified as being the most vulnerable, the royal college’s publication highlights the growing evidence that people with serious mental illness, including depression and psychosis, are more likely to use cannabis or to have used it for long periods in the past. It also appears that regular use doubles the risk of developing a psychotic episode or long-term schizophrenia.

Research has found that adolescents who use cannabis regularly have a significantly higher risk of developing depression, anxiety and psychotic illnesses such as schizophrenia and bipolar disorder. A longitudinal study of 1,600 Australian adolescents, already described by the hon. Member for Central Suffolk and North Ipswich (Dr Poulter), found that while children who used cannabis regularly had a significantly higher risk of depression, the opposite was not the case, with children who already suffered from depression no more likely than anyone else to use cannabis to ameliorate their problems. The study found that adolescents who used cannabis daily were five times more likely to develop depression and anxiety in later life.

Evidence also shows that individuals who use cannabis, particularly at a younger age—around 15, which is when many people start to use it—have a higher than average risk of developing a psychotic illness. It has been found that the increased risk is related to increased use, and that those who use cannabis are also at risk of an earlier onset of illness compared to those who do not.

Available research shows that people with a family history of psychotic illness, or those who have certain characteristics or a certain vulnerability, may be at an increased risk of developing an illness following the regular use of strong cannabis. As has been eloquently described, research also indicates that the UK market has been flooded with stronger varieties of cannabis, such as skunk, which contain higher quantities of tetrahydrocannabinol, or THC, which is cannabis’s main psychoactive ingredient. It has been found that there is a higher risk of developing a psychotic illness from cannabis if it has high levels of THC, and if people are regular users. The easy availability of the stronger varieties carries a specific risk to young people with a genetic predisposition. In addition, it has been highlighted that cannabis with high amounts of THC can cause cognitive problems, such as with short-term memory and processing speed.

While in the past it was thought that cannabis was not addictive, current evidence suggests that it can be, particularly if it is used regularly and heavily.

[Mr Lilley]

We obviously listen with great respect to the hon. Lady because of her expertise, as we did to my hon. Friend the Member for Central Suffolk and North Ipswich (Dr Poulter), who has similar expertise. I just wonder whether the studies that she and he have mentioned consider the prevalence of the illnesses in society as a whole, and whether the recent decline in cannabis use has led to a decline in the incidence of the illnesses. Similarly, when there was a rise in the use of cannabis, did that lead to a rise in their incidence? Is the incidence greater in countries with high cannabis use than in countries with low use, or has such research not yet been done?

[Dr Cameron]

The studies I mention do not specifically answer the right hon. Gentleman’s questions, but they indicate that people with particular vulnerabilities might be more likely to develop mental health problems, along with individuals with heavy and sustained cannabis use. It was not necessarily that a vulnerability was required for someone to go on to develop depression or anxiety.

Regarding physical health, it appears that the main risk from cannabis is that from the tobacco that it is often smoked with, although the British Lung Foundation reported in 2012 that cannabis smoking carries a greater risk of smoking-related disease than tobacco alone. It has also been reported that cannabis can affect fertility, and new research has found that the cannabis plant contains cancerogenic mutagens that can affect the lungs.

In conclusion, it is my position that further research, and perhaps the addressing of the level of schedulisation of cannabis, would be particularly helpful for medical conditions, and that at some point in the future there might be a case for prescribed use for certain conditions, where it is shown to have an ameliorative effect on an individual’s health. Overall though, there appear to be significant mental—and some physical—health concerns associated with cannabis use, which make it necessary for careful consideration to be given to the most effective methods of managing and addressing the issue and to any changes to legislation.