Posted on January 24 2019
While cannabis use is widely expanding and governing laws are adapting to allow people the medical treatment they need, not everyone is a fan of the plant. One discouragement often mouthed by non-supporters is that cannabis has a negative impact on memory or causes memory loss. When you delve into the science behind the plant and its effect on the brain, you quickly find that there is some truth to the claim. However, it’s not nearly as severe as people like to think, and it’s not likely to leave you in a confused stupor after a smoking session (much like alcohol).
Memory loss when high is possible, but the chance of it affecting your long term memory is very slim. The science lays it all out, including the small amount of truth behind these fear-mongering claims, and the real impact cannabis has on memory functions.
The Truth in the Memory Loss Claim
The tidbits of truth to the memory claims lie in the short term effects of cannabis on memory. In short, research suggests that cannabis may make it more difficult for the brain to store new memory data or to recall short-term information. However, this is only found to be true within the duration of the high (and sometimes up to two hours afterward).
It has something to do with THC’s effect on cognition, but it isn’t a big deal for most people. To be safe, you wouldn’t want to get high before studying for a big test or attending an important event that you want to remember in detail.
Long term effects of cannabis on memory have also been tested, and research proved that heavy cannabis use can decrease your brain’s ability to store memories and recall information over time. The test involved a group of heavy pot smokers and a group of people who smoked significantly less or not at all. They were asked to hear a set of fifteen words and recall as many as they could.
The non-smoker group outperformed the heavy-smokers, but by only marginal amounts. In fact, the non-smoker group recalled words at a rate of less than 0.05% higher than the heavy-smoker group. Again, this insignificant impact is usually not enough to stand in between a medicinal user and their powerful, plant-derived relief.
Where the Memory Claims Come From
The small impact on short term memory is one of the only proven claims that suggests cannabis negatively impacts memory. Otherwise, cannabis shows no negative impact on memory. In fact, it seems to have no effect on your ability to recall long-term memories or stored information. Most of these scare tactics come from misinterpreted or debunked data. For instance, one study talks about the adverse effects of memory after long term use of synthetic cannabinoids, which is not derived from the cannabis plant. Headlines read “Marijuana Causes Memory Loss” and people ran with it.
One popular study may have also led to the claim that cannabis causes memory loss, but it has been identified as an unreputable source. The study involved over 1,000 participants, many who regularly used cannabis for long periods of time. The study looked at their I.Q. rating at the age of 13, and then five more times throughout their life, until the age of 38. The study suggested that heavy cannabis users experienced an I.Q. decrease of around 4 points.
However, as researchers later suggested, there was no way to closely control environmental factors throughout the study. The study does not confirm or deny the possibility that participants used other mind-altering substances. It also does not factor in socio-economic standards, the home life for participants, or other factors that could have resulted in the I.Q. drop.
The study was later debunked after a similar study looked at identical twins, a mix of whom did and did not use cannabis. The I.Q. point drop was nearly the same across each set of twins, regardless of their cannabis use status.
Cannabis for Suppressing Negative Memories
While everyone seems to be up in arms about the memory-loss claims, many overlook the positive effects that cannabis may have on memories. Some evidence suggests that cannabis may be useful for repressing or erasing harmful memories, like those found in patients who suffer from PTSD. Evidence suggests that cannabis may be useful for treating anxiety and sleep disorders related to PTSD. Another study suggests that cannabis may even be able to reduce or eliminate the nightmares, which are usually based on stored memories, in people suffering from the conditions.
CBD May Be Memory Protective
Unlike THC, cannabidiol (CBD) has no impact on cognition. Because of this, it is unlikely that CBD is responsible for any of the adverse effects on memory that are listed. Instead, evidence suggests that cannabis may protect memories by reversing or counteracting the effects of THC on cognition and episodic memory. While studies have suggested that cannabidiol is wake-promoting, and may lead to alertness, more research is needed to identify it’s full effects on memory.