Does Cannabis Really Affect Memory?

November 10, 2022
3 mins read

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The earliest evidence of human consumption of marijuana dates back to 2500 BC for spiritual and medicinal purposes. Nowadays, many people still debate the positive and negative effects cannabis offers. The research on its side effects remains limited because of its illegal status in the United States and many other countries. The results of existing studies are mixed, with some suggesting that smoking weed can impair human memory and cognitive abilities.

A Bit of Science

To talk about how cannabis affects memory, let’s define some notions. Memory is divided into short-term and long-term. Short-term memory temporarily stores immediate effects, and long-term memory stores information for an unlimited time period.

Another important fact to know is that the human nervous system relies on the endocannabinoid system, a communication network of receptors formed by neurons in the brain that regulates important body functions, including memory. Cannabis contains active compounds called cannabinoids that can interact with specific receptors in the central nervous system and regulate how brain cells communicate.

Negative Effects

More than 100 cannabinoids have been identified in weed. Tetrahydrocannabinol (THC) and cannabidiol (CBD) are 2 prominent cannabinoids that naturally occur in cannabis. THC is a psychoactive compound that attaches to human brain receptors and may disrupt their function, causing short-term memory loss. The trial conducted in 2006 showed that people who smoked marijuana for more than 10 years performed worse on a test of cognitive abilities than participants who didn’t consume cannabis. The 2021 research leaned towards the fact that heavy marijuana users had long-term memory impairment, while occasional consumers evidenced no negative effects. Also, the negative effects on cognitive functions can be reversed with abstinence from weed consumption.


As research on cannabis’s effects on the human brain expands, so do the conclusions. Though the negative effects of weed on short-term memory are well-known, its effects on long-term memory are not consistent. Recent research on Alzheimer’s patients and those with epilepsy has uncovered positive results and proved that marijuana could be useful in treating and preventing senior dementia. The medical marijuana volunteers had higher scores of memory retention during the test. Cannabis has the potential to slow down the advance of neurodegenerative diseases and provide restoration of cognitive functions through the creation of new neurons.


These paradoxical effects are explained that CBD and THC are both present in cannabis. THC creates euphoric effects, while CBD diminishes the feelings of euphoria. As a non-psychoactive component, CBD has calming and relaxing properties and helps individuals diagnosed with post-traumatic disorder forget their intrusive and painful memories. It helps cope with brain diseases that affect the human mind, such as dementia and Parkinson’s.

CBD hosts many other benefits for brain health:

  • CBD has neuroprotective properties that protect neurons from degeneration and damage.
  • Due to its antioxidant properties, CBD decreases oxidative stress, which leads to brain cell degradation.
  • CBD suppresses agitation and reduces stress levels, helping the brain better recall memories.
  • Thanks to its anti-swelling properties, CBD increases blood flow to the brain and diminishes the risk of memory loss.

Various types of cannabis include different ratios of THC and CBD. Strains with a high THC level (like the Fruity Pebbles strain) and no or low amounts of CBD may have a detrimental effect on memory, especially in adolescents. They increase the risk of developing mental health problems. People lose the ability to retain and recall information, but fortunately, it is not permanent.

Risks of Using Cannabis

In some cases, establishing that cannabis has caused impaired memory is tricky because the reasons for developing this disorder can differ. It can be caused by other drugs people have used. Alcohol abuse can also cause memory loss and brain damage. Like higher doses of alcohol, frequent cannabis use hinders the ability to concentrate on a task and learn effectively. Alcohol is known to severely damage or destroy brain neurons and their signalling functions, while cannabis changes the neural brain tissue responsible for memory. If a person stops using weed, these changes can be reversed within several weeks.

Teen brains are particularly vulnerable to these effects. Young people who use cannabis frequently have thinner frontal and temporal cortices that help process memory functioning. Aside from affecting memory, marijuana reduces motivation to learn and adolescents’ engagement in education.

Senior cannabis users (50 and older) have only a moderate impact on their cognitive functioning and memory. The nature of this modest decline has not been properly studied yet.

Summing up

More studies need to be conducted regarding the relationship between cannabis and memory. Marijuana remains illegal at the federal level, and it is difficult for U.S. researchers to obtain funding to study the properties of this plant. What is clear for certain is that there is no great harm to a person’s memory if people use weed occasionally. There is a greater risk of developing mental problems with long-term cannabis use; however, current evidence suggests that memory impairment can be reversed if people abstain from marijuana.

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