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Experts say a new study suggesting cannabis use can cause “false memories” may make the findings sound more nefarious than they really are. Getty Images
  • New research suggests cannabis use could make a user more susceptible to “false memory.”
  • However, experts say this is a somewhat misleading term that makes the findings sound more nefarious than they really are.
  • Instead of being more susceptible to “false memories,” experts say a cannabis-impaired person is likely “more suggestible” and may recall inaccurate details when asked suggestive questions.

Past research from the World Health Organization has linked recreational cannabis use to impairing a person’s attention and delaying their reaction time, resulting in a doubled risk of fatal traffic accidents.

In the short term, cannabis can lower a person’s working memory, executive function, and attention.

But new research suggests cannabis use could make a user more susceptible to “false memory,” a somewhat misleading term some experts say sounds more nefarious than it really is.

A recent study published in the Proceedings of the National Academy of Sciences of the United States of America suggests that cannabis seems to increase “false memory proneness,” meaning they may claim to remember something that wasn’t there.

That doesn’t mean that normal cannabis use will make someone hallucinate dragons or their pets talking.

Rather, they’re more prone to remember words that weren’t on a test and more susceptible to “suggestion-based” false memories, as even single doses of cannabis have shown to affect a person’s decision making and working memory.

To test this effect, researchers in the Netherlands, Australia, Germany, and the United States recruited 64 healthy adult volunteers for their randomized, double-blind, placebo-controlled trial.

Some people were given cannabis and others were given a placebo. All underwent memory tests, including standardized and trusted word tests, all the way to relaying information after undergoing scenarios in virtual reality, including as an eyewitness and the perpetrator of a crime.

Then, a week later, misinformation was introduced through a combination of suggestive questions in a follow-up interview and through a virtual co-witness.

Overall, the researchers found those given cannabis without knowing they’ve received it were more likely to experience “enhanced false-memory effects,” but those mostly played out when someone was high.

“Although cannabis is oftentimes connected with positive effects (e.g., pain reduction), it might also lead to hazy memories, which eventually opens the door for a negative effect: increases in false memories,” the study concluded.

The real-life ramifications, researchers note, fall on police officers and other investigators who are seeking the most accurate and truthful statements from witnesses, including those under the influence of cannabis.

To do so, researchers note, investigators should wait for them to sober up, otherwise they’ll be more susceptible to confirming leading questions and not necessarily pulling truthful details from events they may have just witnessed.

But they shouldn’t wait too long.

The researchers found that after a week, the high participants and the sober ones had about the same rate of memory recall, suggesting the effects of cannabis’ impact leveled out with our natural loss of memories in the short term.

To Dr. Mary Clifton, a New York City–based cannabis expert who wasn’t involved in the study, the findings suggest that whether people are sober or high, their ability to recall what they saw found a middle ground just a week later.

“That’s so strange,” Clifton told Healthline. “The sober people lost memory over time.”

That’s also because we all lose some memories over time, as our brains decide what’s important and what’s not, even if that includes details of a crime just 1 week ago.

Clifton says because of how cannabis interacts with the hippocampus — a part of the brain associated with memory — the findings between sober and high witnesses at a week later merit for more study.

Regardless, she says, as different substances work differently in the brain, finding truth in an investigation should involve considering the state a witness may be in.

“I don’t think police anywhere should be interviewing anyone who is high or drunk,” Clifton said.

In terms of the criminal justice system, the findings may be more helpful to defense attorneys or others who would cross-examine so-called eyewitnesses.

Or are people simply “more suggestible” when they’re high?

Dr. Jordan Tishler, a Harvard-educated physician and CEO of inhaleMD, who also wasn’t involved in the research, found it “insanely interesting” for its approach and methodology, namely by mixing tried-and-true methods with newer technology, like virtual reality.

But he did take issue at the study’s title — “Cannabis increases susceptibility to false memory” — as he says it “evokes all sorts of boogeymen.”

“The headline comes off as saying anybody who uses cannabis is untrustworthy, and I don’t think that was the authors’ intentions,” Tishler told Healthline.

Instead, he says, the findings suggest that people under the influence of cannabis are more agreeable and more likely to “go along to get along.”

Much like a child trying to please a parent, someone under the influence of cannabis may be more likely to follow along with leading questions.

Instead of being more susceptible to “false memories,” Tishler argues a cannabis-impaired person is “more suggestible.”

“Stoners would say ‘yes’ more,” Tishler said.

That means how a question is phrased is even more important.

For example, asking someone, “Did you see the white car?” while they’re high may get them to answer yes more often, even if the car was red, blue, or black.

Instead, asking “What did you see?” could elicit more truthful answers and go against a cannabis-impaired person’s inclinations to be helpful, even if their answers aren’t exactly spot on.

While finding the research interesting due to how it relates to people’s memory while under the influence of cannabis, Tishler says this line of research, so far, will likely have little effect on the criminal justice system.

“I’m not sure it has many practical implications,” he said. “It gets into the legal part and, for me as a non-lawyer, that makes me batty.”