Cannabis may make you remember things that never happened

Most people think of cannabis as something that makes memories fuzzy. But new research suggests it can do something more surprising: make false memories feel real.

While cannabis is often associated with forgetfulness, a new study suggests that acute cannabis intoxication can also subtly distort memory, shaping not just what we recall, but how accurately we recall it. The findings expand on decades of research on cannabis and recall, pointing to a more complex effect on the brain’s memory systems.

To understand why, researchers are examining granular aspects of memory, such as false memory, source memory, prospective memory, and temporal order memory—and how each responds to THC.

What cannabis does to our memory

Although THC can produce desired effects such as euphoria, pain relief, and nausea control, it may also disrupt other processes, including memory formation. When we experience something—going for a hike, celebrating a birthday—different parts of our brain help process the thoughts, senses, and emotions that make up that moment. The hippocampus helps bind those elements into a memory that can later be retrieved.

Scientists generally describe memory as a three-part process: encoding (when the brain first takes in information), consolidation (when that information is processed and stored), and retrieval (when it is accessed later). “You are activating certain pathways to create a memory,” says Carrie Cuttler, an associate professor and director of the Health and Cognition Lab at Washington State University and co-author of the 2026 study, “and to recall something, you are trying to reactivate that same pathway.”

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But how cannabis interacts with this process is not totally understood, since “drugs affect all three phases of memory differently,” says Lilian Kloft-Heller, an assistant professor of psychopharmacology at Maastricht University.

Part of the answer lies in the body’s endocannabinoid system, a signaling network that helps our bodies regulate numerous processes. This system includes naturally produced endocannabinoids, which carry the signals, and the CB1 receptors, where the message is received. THC, the primary psychoactive compound in cannabis, can also bind to CB1 receptors.

“If you blast the system with THC, the THC hijacks the system,” says Cuttler. Instead of your CB1 receptors activating in a controlled pattern, they become overstimulated—more like Times Square on New Year’s Eve than a field of fireflies.

In the 2026 study, Cuttler and her co-author randomly assigned 120 cannabis users to vaporize a placebo or doses of THC (20 or 40 milligrams). Participants were then given 21 memory tests, many of which had not previously been studied in relation to cannabis.

About 70 percent showed some level of impairment, including temporal order memory (remembering the sequence of events) and source memory (identifying where information came from). False memory and source memory showed the largest effect of cannabis.

How false memories form

False memories don’t come from nowhere—they emerge when the brain tries to make sense of incomplete information. When encoding is disrupted, fewer details are accurately stored. Later, during retrieval, the brain doesn’t simply “play back” a memory—it reconstructs it.

And when information is missing, it may fill in the gaps with general knowledge or familiar patterns. For example, if you usually get a burrito when you go out with your friends, but instead choose tacos one night, you might later remember the more familiar choice.

Psychologists often distinguish between recollection, which involves recalling specific details of an event, and familiarity, a more general sense that something has been experienced before. THC appears to shift that balance—weakening detailed recollection while leaving familiarity intact.

It can also impair source memory, the ability to remember where information came from. You might remember a fact, for instance, but not whether you read it in a book or saw it on social media. In Cuttler’s study, participants under the influence of THC were significantly worse at knowing whether items were from pictures or printed words.

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At the brain level, these effects are linked to how THC interacts with the hippocampus, a region critical for memory consolidation. A 2016 study published in Nature found that THC can activate CB1 receptors in hippocampal cells in ways that disrupt the energy processes neurons need to stabilize new memories. Without that stability, memories may be stored with fewer precise details.

In the Netherlands, a 2020 study found that cannabis users were more likely to “remember” words they never actually heard. Researchers described this as a criterion shift, meaning participants became more likely to accept information as true, even when it wasn’t. Cuttler’s study found the same effect: users had nearly twice as many false recalls as those on a placebo.

What scientists still don’t know

As researchers dig into specific types of memory, many questions remain—particularly around how individual factors shape cannabis’s effects.

For example, some females react differently to cannabis, says Kloft-Heller. Some research suggests cannabis use is more strongly linked to disruptions in episodic memory in women. At the same time, men may be more affected in areas like decision-making, though findings are mixed and still emerging.

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The method of consumption may also play a role. Edibles are far less likely to induce memory effects than inhalation, due to differences in metabolic pathways.  Inhaled cannabis produces a rapid spike in THC levels, while edibles are metabolized more slowly, leading to a delayed but longer-lasting effect. How these differences translate to memory outcomes is still not well understood.

The good news is that the effects of cannabis on memory are not typically dramatic. “Acute alcohol intoxication is generally more disruptive to memory than cannabis,” says Cuttler. And if you are looking to improve your memory, THC effects appear to fade with sobriety: “if a person abstains from cannabis for a month, we expect a complete rebound,” Cuttler says.