Back in high school there was a group of kids in my AP Physics class who would smoke weed before every test.  And, they’d ace the tests every single time!  They would just knock it out of the park.  I had no trouble acing my math and science classes in high school until I took this class.  It was incredibly difficult.  I remember spending hours and hours struggling to solve just 1 homework problem.  You were lucky if you walked away with a C in this class.  Even though I was a total square back in high-school, I can tell you I was tempted to join those kids.  Because, in the back of my mind I was convinced that the marijuana was enhancing their performance on these tests.

Let’s find out if there’s any truth to this.


I’m going to discuss the results of a study that looked at the effects of marijuana on cognition.  First of all, what’s cognition?

It’s a word used to describe the processes that go run through our brain on an everyday basis, like

paying attention,

remembering something old,

learning something new,

solving a problem,


making a decision,

interpreting information that your eyes, ears, nose, fingers, and mouth give you,

communicating by reading, writing, speaking and listening


So hopefully, that gives you a better idea of what cognition means.

Effect of Marijuana on Memory: The Research

Now let’s get back to the research on medical marijuana’s effects on cognition.

This study was done in 2016 by folks at Harvard and Tufts University.  They saw that there’s a good amount of research on the effect of marijuana on cognition in recreational marijuana users, but in medical marijuana users.

And, there’s a huge difference between the 2.  Obviously, there’s a difference in their intention of use.  One group is specifically using marijuana to get high.  While, the other group is clearly using it to relieve symptoms or treat certain medical conditions.

Because of this, there’s a difference in the type of marijuana the 2 groups select.  And, also how much and how often they use it.

As you can imagine, all of these factors combined then affect cognition differently.

This particular study looked at the impact of 3 months of medical marijuana use on cognition in 11 participants.

The participants took a battery of tests before and after using medical marijuana for 3 months.  Now, in these 3 months, these participants used medical marijuana anywhere from 1 to 7 days a week with an average of 5 days per week.

Let me describe each of the tests these participants had to take.

One of the tests was the Stroop Color Word Test.

There are 3 parts to this test.

First you’re asked to indicate what color of ink a row of Xs are printed in.

Then you’re asked to read words that are printed in black ink.  The words are names of colors.

Finally, you’re asked to indicate what color a bunch of words are printed in.  These words are names of colors.  But, they’re not printed in the same color ink as the name of the color.  So, for example the word red will be printed in green ink.  And, the word blue will be printed in red ink.

Now, the goal is to complete the task as quickly as possible.

Another test was the Trail Making Test.

This is basically a connect the dots test.  First you’re asked to connect the dots by numbers. Then you’re asked to connect the dots by alternating numbers and letters.  So, the number 1 is connected to the letter A, which is connected to the number 2, which is connected to the letter B, etc.

Then, the participants were asked to complete the Wisconsin Card Sorting Test.

The participants are given a deck of cards.  They’re told to match the cards, but they’re not given any more instructions other than that.  In other words, they’re not told if they have to match by shape, by color, or by number.  Instead, the computer tells them if they were right or wrong.  Initially, they were just guessing.  Based on that the participants eventually figure out how to match the cards.  But, then the computer switches the rules on them.  It’s a test that keeps you on your toes.

And, finally, the participants had to complete the Letter-Number Sequencing Task.

In this task, participants are asked to read longer and longer sequences of letters and numbers.  They’re then asked to repeat them.  But, first they have to say the numbers in numerical order and then they have to say the letters in alphabetical order.

Overall, the participants completed the tests faster after the 3 months of medical marijuana use than before.  And, this was without sacrificing accuracy.  On some tests, there was no difference in the number of errors between before and after use of medical marijuana.  And, on other tests there was actually an improvement in accuracy.  So, the medical marijuana didn’t hold back their performance in any way.

Effect of Marijuana on Memory: The Why

Why these results?

Research has shown that both chronic pain and anxiety interfere with tasks like planning, focusing attention, remembering instructions, and juggling multiple tasks successfully.

So, it’s possible that reducing anxiety and chronic pain could help to improve cognitive functioning.  Basically, if physical or psychological symptoms are addressed, cognitive function improves.

And, in fact, the participants did report a lower level of sleep disturbance, decreased impulsivity, increased energy, and decreased fatigue.

They also reported an overall improvement in their quality of life.  Specifically, they didn’t have to cut down as much on work or other activities.  They accomplished more than they expected.  They didn’t have as much difficulty performing their work or engaging in activities.

Many of these participants were also able to cut down on or eliminate their prescription drugs.

All of these factors combined could ultimately lead to an improvement in cognitive functioning.

It’s important to know that the researchers plan to recruit even more participants for the study, continue this work, and assess the participants cognitive functioning at 6 and 12 months.



Effect of Marijuana on Memory: Research Referenced

If you have further questions on the effect of marijuana on memory, then please post them in the comments section below.