High-potency Cannabis Linked to Poor Mental Health, Study Finds
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Frequent consumption of high-strength cannabis is associated with poor mental health and addiction, according to a new cohort study published in JAMA Psychiatry.
As the study relied on the testimonies of people who consume cannabis, its findings don’t prove a causal relationship between the drug and any mental health condition.
Yet, in light of other studies that have found similar associations, the research could still have vital implications for public health approaches to cannabis legalization.
To reach their conclusions, the researchers interviewed 1087 young people (average age of 24) who claimed to have consumed cannabis in the past year.
The majority of the group (87.2 percent) said they consumed low-potency varieties, such as low-THC herbal cannabis. Only 12.8 percent claimed to use high-potency products, such as hashish. But these high-strength cannabis consumers were more likely to report problems associated with the drug.
“So things like experiencing memory problems as a result of cannabis use,” Dr Lindsey Hines, a researcher at the University of Bristol and senior author of the study, clarified to Analytical Cannabis.
“Having tried to cut down but not being able to, your family being concerned about your use, getting into arguments of your use[…] People who report two or more of those items, we’d say they’re experiencing problems.”
Of all the mental health conditions considered by the researchers, generalized anxiety disorder was most closely associated with high-potency cannabis use. There was no clear correlation with depression, which may illuminate the reasons underlying heavy cannabis use.
“When we do research into cannabis and mental health, people suggest that what we’re seeing is a kind of artefact of self-medication – that people use the drug to attenuate their own mental health symptoms,” Hines added.
“And I think the fact that we see an association with anxiety but not depression is kind of an argument against that in this case. Because, anecdotally, people use cannabis to help deal with their anxiety and depression[…] So the fact that we’re only seeing this for anxiety supports the case that this is less likely to be self-medication.”
The high-potency group were also more likely to consume cannabis and other illicit drugs more frequently than the other participants.
The bigger picture
While the study could have wide implications for public health policies around cannabis use, it also has its caveats.
As the study’s participants were drawn from a multi-decade-long study group in Avon, England, their habits may not be entirely representative of cannabis use across the UK or other countries with legal recreational models. Many of the participants, for instance, were from backgrounds more affluent than the general population.
“[The study cohort] has been going on for a long time,” Hines told Analytical Cannabis. “So, by this time point, we have got a less representative sample; they're more likely to be affluent, they’re much more likely to be white than the general population, and more likely to be of higher socioeconomic status.”
Despite these limitations, the evidence from the sample group can still help form public health policies, according to the researchers. Limiting the availability of high-potency cannabis, they say, may be one measure to curb anxiety disorder cases.
“There is a strong indication that, by regulating the potency of the drug, you can maybe reduce those problems that people are going to experience from use,” Hines added.
Putting potency caps on cannabis products is a central pillar in many public health-focused arguments for cannabis legalization.
In Canada, for example, there is a 10 milligram THC limit per unit of solid and drinkable cannabis edibles. The governments of New Zealand and Luxembourg are also reportedly considering THC thresholds as part of their own respective legalization efforts.
“Jurisdictions that are considering legalizing cannabis will need to consider strategies that discourage heavy use, such as a tax that based on cannabis potency and restriction on marketing practices that target heavy users,” Dr Gary Chan, a substance abuse researcher at the University of Queensland, Australia – who was not involved in the recent JAMA Psychiatry study – told Analytical Cannabis earlier this year.
Speaking to Analytical Cannabis last November, Ian Hamilton, a senior lecturer in addiction at the University of York, also stressed the importance of fortifying public health policies to tackle cannabis dependence.
“For the small proportion of users who develop problems, support services need to be adequately funded and available – something [US] states and countries should factor in when thinking of changing their cannabis policies,” said Hamilton.
“Even a small percentage increase in regular cannabis users can increase the risk of developing problems like cannabis dependence, which services would be unlikely to have the capacity to support,” he added.