Health and Medicine
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If you’re not aware of cannabis’s detrimental effects on memory by now, well, we can only assume you got too high and forgot. And it’s not just anecdotal: research has repeatedly borne out that acute cannabis use makes it much harder to remember things.
The rest of this article is behind a paywall. Please sign in or subscribe to access the full content.But so far, almost the only specific types of memory that applies to has been verbal and working. While important metrics, these basically refer to just remembering lists of words and pieces of information respectively – in other words, they don’t necessarily reflect every kind of memory your brain needs in a day. How does cannabis impact, say, your prospective memory – the ability to remember to do things in the future – or your episodic memory of events you personally experienced?
That’s precisely what a new study from Washington State University researchers Carrie Cuttler and Ryan McLaughlin aimed to find out. But here’s the problem: how do you measure the immediate effects of cannabis consumption on memory?
Turns out, the answer is simple. You just get a bunch of people high, then give them each a memory test.
“Participants were brought to a vaping room,” the paper reports, and “instructed to inhale for a minimum of 2 seconds, hold for a minimum of 2 seconds, and then exhale.”
There were 120 participants in all – which admittedly isn’t a lot – all recruited from dispensaries around Washington State University campus. Once recruited and confirmed, they were split into three groups: one was given a high dose of cannabis, one a moderate dose, and one received only a placebo (interestingly, the paper notes that one participant in the placebo group quit the study because they “found the effects too strong”).
Once assigned their respective vape mix, “they were instructed to inhale the full dose,” the authors write. “The experimenter observed the participant during the vaping session and timed the duration of each inhalation and hold and recorded the number of puffs each participant took […] They then completed approximately 1 hour of memory tests.”
Buzzkill? Maybe. But this barrage of memory tests yielded some revealing results: “there were significant main effects of drug condition on five of the six verbal memory test outcomes, two of the four visuospatial memory test outcomes, one of the two prospective memory tests, both measures of source memory, four of the five measures of false memory, and the temporal order memory test,” the paper reports.
“The only domain that failed to reveal a significant effect of cannabis exposure was episodic content memory,” it says. “In total, 15 of the 21 (71 percent) outcomes revealed significant effects of acute cannabis use.”
Evidently, cannabis use isn’t great for your memory – at least in the short term – and the detrimental effects are far wider-ranging than had previously been confirmed. It’s not just remembering strings of words or nuggets of information; getting high will also impact your ability to remember and recall in for far more useful everyday ways.
It sounds pretty bad. But here’s the thing: it might be even worse. Many of the limitations of the study – things like the comparatively young mean age and generally high THC tolerance of the participants; various cushioning effects from the design of the study, like asking participants to repeat instructions in their own words or allowing the use of clocks – likely act to reduce the effects of cannabis on memory. In real-world situations, they could be much worse.
That, particularly in the context of rising daily cannabis use across North America, all means one thing: more research is sorely needed.
“As cannabis becomes increasingly accessible, understanding its immediate cognitive consequences is essential,” the paper concludes, “[both] for informing public health policy, shaping responsible use guidelines, and mitigating potential harms to individuals and society.”
The study is published in the Journal of Psychopharmacology.
