Is weed bad for you? Brain function could be impacted when sober - study

Cannabis has numerous positive qualities and is often prescribed as a medication. But residual effects can impact cognitive function even when one sobers up.

An employee inspects the leaf of a cannabis plant at a medical marijuana plantation in northern Israel. (photo credit: NIR ELIAS / REUTERS)
An employee inspects the leaf of a cannabis plant at a medical marijuana plantation in northern Israel.
(photo credit: NIR ELIAS / REUTERS)

Is using marijuana bad for you? While the topic has been debated by experts for many years in terms of exactly how cannabis affects the human body and how severe or long-lasting these effects may be, one new scientific study has concluded that yes, weed's effects on one's brain can last after one sobers up.

This conclusion was revealed in a new Canadian-led meta-review, which essentially merged the results of 10 different meta-analyses with over 43,000 participants studied. 

The findings of this meta-review were published in the peer-reviewed academic journal Addiction.

Marijuana, also known as cannabis, weed, pot and a number of other colloquialisms, is an extremely popular psychoactive substance across the world. It has been used for centuries and, despite many years where it was held in disdain in popular culture for perceived harmful effects, has now gained widespread acceptance in mainstream discourse where its use has become increasingly normalized.

Cannabis has been shown to be far healthier than many other substances like tobacco and alcohol, possessing few addictive traits. It has also been shown to possess many positive qualities, and this is reflected in its use as a prescribed medication for treating a wide variety of different conditions, from anxiety and post-traumatic stress disorder to insomnia, chronic pain and aiding in helping cancer patients cope with chemotherapy.

A man prepares a cigarette mixed with marijuana during Cannatech 2017, an annual global cannabis industry event, in Tel Aviv, Israel March 20, 2017. (credit: REUTERS/AMIR COHEN)A man prepares a cigarette mixed with marijuana during Cannatech 2017, an annual global cannabis industry event, in Tel Aviv, Israel March 20, 2017. (credit: REUTERS/AMIR COHEN)

Research has even suggested it could help prevent infection with COVID-19.

The highs and the lows of cannabis use

But that is not to say there aren't any downsides to its use. When one uses cannabis, they become intoxicated. While this is not to the same extent as getting drunk on alcohol, its impacts are still noted. Cannabis can impact one's mood, heightening panic or relaxation, and can affect the release of different important neurotransmitters like serotonin and dopamine. It can influence memory, attention span and the ability to think and concentrate. 

While under the influence of marijuana, a state known in layman's terminology as "being high," one can struggle to make decisions, they may have trouble holding back inappropriate responses and their thinking speeds might considerably slow down.

Normally, this isn't seen as something too concerning, so long as cannabis is used responsibly like alcohol. The state of intoxication usually only lasts a few hours, at most.

But that assumption might not be wholly accurate.

Much of the psychoactive qualities in marijuana comes from the cannabinoid compound known as THC. This is linked to the effects cannabis use can have. 

In other words, THC is what gets you high.

As stated earlier, one only stays high for a few to several hours. 

But, as noted by researchers, THC is fat-soluble. This means that rather than just going in and out of the body, it can actually be stored in body fat, gradually released into the body's bloodstream for months at a time.

This is why researchers have wanted to study not only the cognitive effects of getting high, but the residual effects that happen after one sobers up.

What happens after getting high?

So have studies legitimized these worries? To an extent, yes, as these impairments can last longer.

“Our study enabled us to highlight several areas of cognition impaired by cannabis use, including problems concentrating and difficulties remembering and learning, which may have a considerable impact on users’ daily lives,” the study’s co-author Dr. Alexandre Dumais, associate clinical professor of psychiatry at Université de Montréal, said in a statement

“Cannabis use in youth may consequently lead to reduced educational attainment, and, in adults, to poor work performance and dangerous driving. These consequences may be worse in regular and heavy users.”

Who is most impacted?

And it is the youth who are most at risk. 

Younger cannabis users tend to make up the largest demographic. But as their brains are still developing, the effects of cannabis use could be more severe.

But that isn't the whole story.

The residual effects are certainly present, but they are not overly severe. Rather, these cognitive impairments are small to moderate. Measures can certainly be taken to mitigate these problems by spreading more information about their use and screening for any problematic issues that could make one especially susceptible to problematic use habits and, therefore, negative residual effects. 

But it is especially in younger users that this is problematic due to their brains still developing. 

There are other issues with the study too, as there are also so many different ways of using cannabis and so many different types of dosing, including cannabis that is low in THC. 

Overall, the findings are important and show that cannabis should be used carefully and in moderation, but most of all, it shows how much more there is to study about marijuana so that we can better understand its effects on the human body.