Research shows the Marijuana affects short term memory. THC, specifically, may impair stages of memory including encoding, consolidation, and retrieval. However, this is usually temporarily and reversible. Furthermore, research also shows that working/short-term memory is not sensitive to CBD-rich extracts and that potentiation and antagonism of Δ9-THC-induced spatial memory deficits is dependent on the ratio between CBD and Δ9-THC. Meaning, CBD might actually counter act the temporary negative effects of THC including memory loss.
https://doi.org/10.1016/j.neuropharm.2004.08.009
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