Mapping the acute effects of cannabis on multiple memory domains: A randomized, double-blind, placebo-controlled study

Cannabis with THC acutely impairs multiple types of memory, not just verbal memory. In a randomized, double-blind, placebo-controlled study (N=120), participants vaporized flower containing 0 mg THC (placebo), 20 mg THC, or 40 mg THC and then completed a broad battery of memory tests. Outcomes covered verbal memory (immediate, delayed, short-term, working), visuospatial memory (immediate, delayed, short-term, working), prospective memory (event-cued, time-cued), source memory, false memory, episodic content memory, and temporal order memory. Relative to placebo, THC increased susceptibility to false memories and impaired verbal memory, visuospatial memory, event-cued prospective memory, source memory, and temporal order memory. Moderate and high THC doses did not differ significantly. The study also highlights that prospective and temporal order memory tasks better reflect everyday memory and relate to daily functioning.