Users of high-potency cannabis four times more likely to report associated problems

May 28, 2020

Science Daily/University of Bristol

Users of high-potency cannabis are four times more likely to report associated problems, and twice as likely to report anxiety disorder, than users of lower-potency strains, according to new research from the University of Bristol.

Published today on JAMA Psychiatry the research uses data from Children of the 90s, a long-term health study that recruited more than 14,000 pregnant women and their babies born in and around Bristol in the early 1990s and has been following their health and development ever since.

This is the first research of its kind to look at data from a general population sample, with previous research into the links between cannabis potency and mental health only looking at clinical and self-selecting samples of people who use drugs. Added to this, the nature of the data available from the Children of the 90s health study enabled the research team to take into account whether mental health symptoms were present before the individual started using cannabis.

Frequency of cannabis use, which is also often associated with increased mental health problems, was also taken into account in order to determine whether this would explain the relationship between higher-potency usage and mental health conditions.

Lead author Dr Lindsey Hines, Senior Research Associate from Bristol Medical School explained: "We know that people who use cannabis are more likely to report mental health problems than those who don't use cannabis, but we don't fully understand how recent increases in the strength and potency of cannabis affects this. This study gives us an estimate of the increased likelihood of mental health problems from use of high-potency cannabis, compared to use of lower-potency cannabis, and we are able to account for the effect that people's early adolescent mental health symptoms may have on this relationship."

The research looked at data collected from participants aged 24 years who had reported using cannabis in the previous year, of which 13 per cent reported use of high-potency cannabis. Participants were also asked about their usage, and those who self-reported two or more of the Cannabis Abuse Screening Test (CAST) items within the past year were classified as having recently experienced problems as a result of their cannabis use. Researchers were then able to compare this data to reported mental health symptoms at age 24 as well as early symptoms of mental health collected when participants were younger.

Dr Hines continued: "People who use cannabis are more likely to report mental health problems than those who don't use cannabis, but reducing the potency and regularity of their cannabis use may be effective for lessening likelihood of harms from use. In countries where cannabis is sold legally, limiting the availability of high-potency cannabis may reduce the number of individuals who develop cannabis use disorders, prevent cannabis use escalating to a regular behaviour, and reduce impacts on mental health. In countries like the UK, where we are not able to limit the availability of high-potency cannabis, we should make sure there is good treatment and support for those who develop problems from cannabis use."

https://www.sciencedaily.com/releases/2020/05/200528115817.htm

How cannabis and cannabis-based drugs harm your brain

July 23, 2018

Science Daily/Lancaster University

Long-term use of either cannabis or cannabis-based drugs impairs memory say researchers.

The study has implications for both recreational users and people who use the drug to combat epilepsy, multiple sclerosis and chronic pain.

They found that mice exposed to the drug long-term had "significant ... memory impairments" and could not even discriminate between a familiar and novel object.

There is little understanding of the potential negative side effects of long-term cannabinoid exposure, though it is already known that heavy, regular cannabis use increases the risk of developing mental health problems including psychosis and schizophrenia.

More and more people are using the drug long-term due to its legalisation in several countries, while more potent varieties are available for recreational users.

Researchers from Lancaster and Lisbon Universities studied the effects of the cannabinoid drug WIN 55,212-2 in mice and found that:

·     Long-term exposure impairs learning and memory in the animals

·     Brain imaging studies showed that the drug impairs function in key brain regions involved in learning and memory

·     Long-term exposure to the drug impairs the ability of brain regions involved in learning and memory to communicate with each other, suggesting that this underlies the negative effects of the drug on memory

Dr Neil Dawson, the lead researcher from Lancaster University said "This work offers valuable new insight into the way in which long-term cannabinoid exposure negatively impacts on the brain. Understanding these mechanisms is central to understanding how long-term cannabinoid exposure increases the risk of developing mental health issues and memory problems."

He also highlighted the relevance of the work to those using cannabinoid-based therapies to treat medical conditions.

"Cannabis-based therapies can be very effective at treating the symptoms of chronic diseases such as epilepsy and multiple sclerosis, and dramatically increase the quality of life for people living with these conditions. We need to understand the side effects that these people may experience so that we can develop new interventions to minimise these side effects."

Professor Ana Sebastiao, lead researcher at the University of Lisbon, said: "Importantly, our work clearly shows that prolonged cannabinoid intake, when not used for medical reasons, does have a negative impact in brain function and memory. It is important to understand that the same medicine may re-establish an equilibrium under certain diseased conditions, such as in epilepsy or MS, but could cause marked imbalances in healthy individuals. "As for all medicines, cannabinoid based therapies have not only beneficial disease-related actions, but also negative side effects. It is for the medical doctor to weight the advantages of the therapy, taking into consideration quality of life and diseases progression, against the potential side effects."

The research was published in the Journal of Neurochemistry and was conducted as part of the European Commission Horizon 2020 funded SynaNET project.

https://www.sciencedaily.com/releases/2018/07/180723132251.htm