A team of Canadian researchers from the University of Montreal, have found that cannabis can cause long-lasting damage to the developing brains of teenagers while the Canadian Government legalised the sale of cannabis for both medical and recreational use for over 18s in June. The study involved 3,800 adolescents, following them for four years. The study was published in the American Journal of Psychiatry, a peer-reviewed journal. The abstract is available to read online.
The participants were around the age of 13 when the study started. They were recruited from 31 different Canadian schools and were asked to give details of both drug and alcohol use once a year, as well as take part in computer cognitive tests. Previous studies have linked both alcohol and drug-use to cognitive problems, such as having problems with attention, learning, decision-making and academic school performance.
The number of teens using cannabis (18%) was low when compared to the number of teens who admitted drinking alcohol (75%), even if they were occasional drinkers. The scientists expected the study to show that alcohol had a bigger impact on the teens’ brains. Instead, they found more errors in the cognitive tests from the teens using cannabis, including when they were taking the drug and after they had stopped. The drug seemed to affect their reasoning, ability to control behaviour and their working memory. The effects were longer-lasting than that of alcohol and were solely attributed to the effects of the drugs.
The Canadian government’s decision to legalise the drug was criticised by some people, including opposition politicians and some indigenous groups. The Canadian government have banned marketing aimed at young people, sponsorship promotion or the use of characters, animals or celebrities in promotions. The provinces are responsible for setting their own limits on use, and some have chosen to raise the age to 19. People are allowed to own 4 plants for their own use, but it will be illegal to possess more than 30g of cannabis in public, grow more than 4 plants in a household or buy from an unlicensed seller. Severe penalties have been set, including 14 years in jail for selling cannabis to a minor.
While the UK has no plans to license cannabis for recreational use, it has recently announced plans to review the use of the drug for medicinal purposes. While the review is taking place, the government will permit clinicians to apply for a licence to use cannabis and cannabis-based medical products for patients who may need it. Cannabis has been linked with benefits for chronic pain, epilepsy, cancer pain, multiple sclerosis, rheumatoid arthritis and Crohns Disease among others. A panel of experts will consider the application on a case by case basis to see whether criteria is met. They will also consider the products proposed and whether there is another, more appropriate course of action. The government hope that decisions can be made within 4 weeks. This may include teens and young people, where the benefits of taking cannabis in the form of cannabis oil may outweigh the possible risks.
Regular use of cannabis has been linked with a number of risks, including causing anxiety and paranoia, confusion, hallucinations and an increased risk of developing psychosis, particularly for young people. Some of these problems have been linked to the strength of cannabis used, which can have varying amounts of THC (tetrahydrocannabinol), the psychoactive compound which causes ‘highs’. It may also be possible to become addicted to cannabis, and some scientists believe that using the drug can lead to other drugs being used. Smoking cannabis can also cause respiratory problems.
The Canadian government believe that legalising the drug will enable them to control the strength of cannabis supplied, and reduce the need for a black market. Although this study seemed to conclude that the drug could affect teen brains, more information will be available in the future, through the easing of regulations.
If someone is currently illegally taking cannabis on a regular basis, then information and help to stop can be found at the Talk to Frank website. The NHS also offers a good summary of the facts about cannabis.
Conrod, P.J., et al., A Population-Based Analysis of the Relationship between Substance Use and Adolescent Cognitive Development, The American Journal of Psychiatry, October 2018