Cannabis may make you remember events that never happened: study finds

A new study suggests that cannabis may do more than simply cloud memory, it could actively distort it, increasing the likelihood that people recall events that never actually occurred.

Researchers say the primary psychoactive compound in cannabis, THC, can influence multiple stages of memory formation, shaping not only what people remember but also how accurately those memories are stored and retrieved. According to National Geographic, while cannabis is often associated with forgetfulness or “fuzzy” recall, scientists now believe its effects on the brain are more complex than previously understood.

How THC interacts with the brain

Memory formation relies on a coordinated process involving the hippocampus, a brain region responsible for organising experiences into lasting memories. Scientists typically describe memory in three stages: encoding, consolidation and retrieval.

During these processes, THC interacts with the brain’s endocannabinoid system, which regulates several functions, including memory. THC binds to CB1 receptors, which can disrupt normal signalling patterns in the brain.

Researchers describe this disruption as a kind of “overstimulation” of the system, which can interfere with how experiences are recorded and later recalled.

Study shows widespread memory effects

In a 2026 experiment, researchers assigned 120 cannabis users to inhale either a placebo or THC doses of 20 mg or 40 mg. Participants then completed a series of memory tests assessing different types of recall.

The results showed that around 70% of participants experienced some level of memory impairment. The strongest effects were seen in source memory, the ability to recall where information came from, and in false memory formation, where individuals mistakenly remember events that never occurred.

Why false memories form

Experts explain that false memories often arise when the brain fills in gaps during recall. If details are missing during encoding, the brain reconstructs the memory later using assumptions, patterns or familiar experiences.

THC appears to weaken detailed recollection while leaving a general sense of familiarity intact. This imbalance can make it easier for the brain to “fill in” incorrect details, leading to memories that feel real but are inaccurate.

Unanswered questions and recovery

Researchers caution that many questions remain, including why individuals respond differently to cannabis and how factors like sex or consumption method influence memory effects. Early evidence suggests inhaled cannabis may have stronger memory impacts than edibles due to faster THC absorption.

Despite these effects, scientists note that cannabis-related memory impairment is usually temporary, with memory performance generally returning to normal after a period of abstinence.