Effects Of Cannabis On Memory

The link between cannabis and poor memory is rooted in pop culture. But what does the science say about how it affects memory?

The answer is just as complicated as the term “memory” itself, which the author said “is not a construct that can be easily measured”. There are several different types of memory (acute, short term, long term), all of which are affected when under the influence. THC (the psychoactive compound in cannabis) is shown to impair memory temporarily in two ways (per the author):

Difficulty encoding/forming new memories while under the influence.

Short-term difficulties recalling events while high, and shortly after.

In the long term, studies such as one published in JAMA Internal Medicine suggest chronic users (who smoked every day) showed more difficulty recalling words compared to those who used less. “[...] On average, [users] recall 8.5 out of every 15 words. In contrast, those who smoked much less or didn’t consume at all could recall 9 out of every 15 words.”

CBD (the non-psychoactive compound), however, is shown to combat — and even reverse — the effects of THC, while also having neuroprotective effects. Several sources, including the National Institute of Mental Health, showed CBD reduced cell death in the brain caused by alcohol.

Together, THC and CBD are effective in blocking bad or traumatic memories, and are also effective in the prevention of neurodegenerative disorders like Alzheimer's, dementia and Parkinson’s disease. More research is needed, but anecdotal evidence from veterans and PTSD sufferers, among others, lend to its proven therapeutic benefits.