Cannabis and Memory

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Many people hear urban legends about the damage that cannabis can do to memory. Most if not all of the myths lack evidence-based research. Additionally, if the tale was from a study, it was cited incorrectly, or the storyteller had a personal bias. This post explores the recent studies involving memory impairment and cannabis.

Thus far evidence points to cannabis temporarily impairing both short-term memory and the ability to make long-term memories from short-term. The experience of memory impairment happens when an acute dose is taking at once or during prolonged exposure. Nevertheless, cannabis does not reduce the ability to recall information once a memory is in long-term storage.

Reductions in attention and short-term working memory function are debatable cognitive impairments associated with cannabis. Both are said to have similar handicaps as short-term memory. Still, they are controversial because of the method of analysis. When running a meta-analysis with a large group of studies, one team of researchers found no causation of cannabis affecting attention or working memory. However, a second team rerunning the analysis with fewer studies found temporary cognitive impairments. Nevertheless, researchers found that the absence of cannabis for approximately 30 days (one month), eliminated any previous cognitive limitations. At a follow-up test of cognition, past cannabis users tested the same as non-cannabis users. Meaning when a person decides to suspend cannabis there may be no lasting cognitive impairments.

One of many cannabinoids is tetrahydrocannabinol (THC); THC is the psychoactive component of cannabis; it is the primary causal agent in temporary memory impairment when using Cannabis. Another cannabinoid Cannabidiol (CBD) whose medical value is still in the infancy of research is antagonistic to many of THC’s impairing effects. CBD reduces the psychoactive effect and cognitive impairments of THC. Thus, taking CBD with THC may counteract any acute and long-term cognitive impairments when using cannabis.

In closing, data shows THC a cannabinoid in cannabis effect short-term memory and diminishes the ability to store short-term memory in long-term storage. However, long-term memory recall is not affected by cannabis use. Cannabis may or may not affect attention and short-term working memory. Suspending use for one month stopped any cognitive impairments associated with cannabis. Lastly, CBD may hinder any acute and long-term cognitive impairments when using cannabis.

References

Broyd, S. J., van Hell, H. H., Beale, C., Yücel, M., & Solowij, N. (2016). Acute and chronic effects of cannabinoids on human Cognition—A systematic review. Biological Psychiatry, 79(7), 557-567.

GRANT, I., GONZALEZ, R., CAREY, C. L., NATARAJAN, L., & WOLFSON, T. (2003). Non-acute (residual) neurocognitive effects of cannabis use: A meta-analytic study. Journal of the International Neuropsychological Society, 9(5), 679-689.

Morgan, C. J. A., Schafer, G., Freeman, T. P., & Curran, H. V. (2010). Impact of cannabidiol on the acute memory and psychotomimetic effects of smoked cannabis: Naturalistic study. The British Journal of Psychiatry, 197(4), 285-290.

Nadia Solowij, R. B. (2008). The chronic effects of cannabis on memory in humans: A review. Current Drug Abuse Reviews, 1(1)

Schreiner, A. M., & Dunn, M. E. (2012). Residual effects of cannabis use on neurocognitive performance after prolonged abstinence: A meta-analysis. Experimental and Clinical Psychopharmacology, 20(5), 420-429.

Volkow ND, Swanson JM, Evins AE, DeLisi LE, Meier MH, Gonzalez R, Bloomfield MAP, Curran HV, Baler R. (2016). Effects of cannabis use on human behavior, including cognition, motivation, and psychosis: A review. JAMA Psychiatry, 73(3), 292-297.

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