MDMA dampens the encoding and retrieval of emotional memories, study finds

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MDMA appears to have a stronger effect on emotional memories than non-emotional memories, according to new research. The finding may explain why the drug has beneficial effects for people suffering from post-traumatic stress disorder and similar psychiatric conditions.

MDMA, more commonly known as the illegal club drug ecstasy or molly, promotes strong feelings of empathy in users. Preliminary research has found that MDMA-assisted psychotherapy reduces symptoms in people with treatment-resistant PTSD.

“Prior to beginning my PhD, I had worked in both psychopharmacology and episodic memory labs, and for my PhD, I managed to find one of the few places where rigorous human episodic memory work was being conducted with rare psychopharmacological manipulations. At that time, a lot of MDMA and psychedelic research was beginning to come out confirming research prior to the banning of these drugs, such as MDMA’s efficacy as an adjunct to psychotherapy for the treatment of PTSD,” explained study author Manoj K. Doss of the University of Chicago.

“PTSD is especially interesting to memory researchers because individuals that suffer from it have these aberrant and strong recollections of negative experiences, yet their everyday memory is impaired. MDMA is also a particularly interesting drug because it has pharmacological and behavioral effects similar to typical stimulants like amphetamine (i.e., Adderall), which enhance memory, yet MDMA impairs memory.

“These conflicting aspects of PTSD and MDMA eventually led to me to explore whether MDMA’s effects on emotional memory could provide a mechanistic account of how it may improve PTSD,” Doss said.

The double-blind placebo-controlled study of 60 healthy volunteers examined the effects of MDMA on the encoding and retrieval of negative, neutral, and positive memories. The researchers found that MDMA did not affect overall memory accuracy, but the drug did diminish the storage and recollection of negative and positive emotional information.

The findings were published in the scientific journal Neuropsychopharmacology.

“MDMA dampens emotional memories whether they’re memories for an experience while under the influence of MDMA or you’re trying to recollect a sober emotional event under the influence of MDMA,” Doss told PsyPost. “These impairments were rather specific for both negative and positive memories (not neutral memories), and they only affected certain memory processes.”

“In contrast, we’ve shown that alcohol much more strongly modulates various aspects of episodic memory,” Doss said. “My speculation is that part of MDMA’s benefit to PTSD comes from the way MDMA distorts the way a traumatic memory is recalled and then selectively dampens the information that is subsequently re-encoded, thereby altering the traumatic memory.”

“One obvious caveat was that the effects we found for negative memories were apparent for positive memories. I suppose this could mean that during MDMA assisted psychotherapy that therapists should be aiming to target the retrieval of negative memories and avoid positive memories, but it is a bit early to make any strong claims before these findings are replicated and extended.”

There is still much to learn about how MDMA affects humans and the potential it has as a medicine.

“Something that would be interesting for future work would be seeing whether MDMA’s stimulant effects are necessary for its effects on emotional memory,” Doss explained. “Typical stimulants like Adderall and methamphetamine actually enhance emotional memory to a greater degree than neutral memories (i.e., essentially the opposite effect of MDMA), an effect that could potentially worsen PTSD.”

“One difference between typical stimulants and MDMA is that MDMA’s strongest effects are on serotonin instead of dopamine and norepinephrine. It would be interesting to test other ‘entactogenic’ drugs on emotional memory that have strong serotonergic effects like MDMA but much weaker stimulant effects (e.g., MDAI).”

“Another distinguishing feature of MDMA is that it is slightly psychedelic owing to its weak affinity for the same receptor that underlies many or most of the effects of psychedelic drugs (e.g., LSD, psilocybin, DMT). The effects of psychedelics on emotional episodic memory have yet to be empirically tested,” Doss added.

“If you would like to see more emotional episodic memory/neuropsychopharmacology content, follow me on Twitter: @manojdoss.”

The study, “MDMA Impairs Both the Encoding and Retrieval of Emotional Recollections“, was authored by Manoj K Doss, Jessica Weafer, David A Gallo, and Harriet de Wit.