The debate over whether marijuana consumption impacts brain function has been raging for decades. Some studies have shown little to no effect well others demonstrate the opposite. The latest in the latter category is a study from the University of Colorado – the largest study of its kind to date.

Its data shows a clear link between heavy cannabis consumption and reduced cognitive ability. Most alarming was a finding that cannabis seems to impact working memory, the kind of memory necessary to understand instructions and solve complex problems.

Researchers categorized the subjects according to historical consumption. Heavy users reported having used marijuana at least a thousandtimes over their entire lives. Those reporting 10-999 were categorized as moderate users while those reporting fewer than ten were considered non-users.

Subjects Were Young Adults

Another point of clarity: all one thousand test subjects were young adults from 22-36 years of age. The subjects were asked to report their cannabis consumption before being subjected to brain imaging technology. Brain imaging helps researchers understand what is going on in the brain when subjects are trying to process information or solve problems.

According to researchers, 63% of the heavy lifetime users demonstrated reduced brain activity while being asked to perform working memory tasks. Interestingly, 68% of recent cannabis users also demonstrated a similar decline.

One would expect a loss of cognitive function in the immediate aftermath of consuming cannabis. But the fact that so many longtime users also exhibited a loss of cognitive function is alarming. It is alarming enough to cause us to step back and think about what we are doing with cannabis.

Less Risk With Medical Cannabis

I am no scientist, but common sense seems to dictate that there is less risk of permanent cognitive impairment among medical users. Why? Because I assume that medical users are consuming cannabis under the supervision of a doctor or pharmacist.

In Utah, the operators of Salt Lake City’s medical cannabis dispensary Beehive Farmacy say it is not unusual for doctors and pharmacists to work together with a patient to determine the best course of action. More importantly, doctors and pharmacists tend to recommend the smallest possible dose and least frequency to provide adequate symptom relief.

Compare that to recreational consumption, where there are no guards or controls. In neighboring Arizona, where both recreational and medical consumption are allowed, recreational users can buy and consume as much marijuana as they want. Using it every day for three years would put a consumer in the heavy consumption camp.

Potency Could Make a Difference

Another thing we need to consider is that potency could make a difference. After all, it is the THC that both recreational and medical users are after. It is also the THC that interacts with the brain to create psychoactive effects. It would seem that higher volumes of THC would create a greater level of impairment.

Due to so many states legalizing cannabis, an entire industry has emerged from coast-to-coast. It is a highly competitive industry, too. Furthermore, all the natural forces of competition are in play.

I say that to explain that growers are competing to see who can produce the most potent plants. Today’s legal marijuana can be considerably more potent than the street weed our parents and grandparents purchased decades ago.

We Need to Slow Down

My take away from the University of Colorado study is that we need to slow down. Hitting the pause button for a while wouldn’t be a bad idea. The more research we do, the more we seem to discover that cannabis isn’t as harmless as so many people think.