This article was first seen in print, as part of our Canna Critic Column.

About this column: The purpose of this column is to highlight important and sometimes challenging issues regarding cannabis. While we remain bullish on the industry, we hope to bring adequate attention to and spark discussion about these important issues.

The benefits of cannabis are often touted from rooftops by passionate consumers, medical patients, and industrialists. On the other hand, negative cannabis news is given very little attention. In this section, we aim to play devil’s advocate or in this case cannabis critic. The posts found in this section will cover important news that may not be easy to hear.

Cognitive Effects of Cannabis: Does Cannabis negatively impact our brain’s ability to reason?

Cognition refers to the brain’s ability to think, reason, or plan. Studies show that acute and chronic cannabis use can negatively impact cognition. To further understand what this means, let’s take a deeper dive into understanding cognition.

Cognition can be divided into six categories: (1) Memory and Recall, (2) Attention, (3) Executive Function and Planning, (4) Language and Naming, (5) Motor Function, and (6) Social Function. Each category can be further divided down into specific cognitive tasks. For example, attention can be divided into sustained attention, selective attention, and processing speed.

Scientists have developed tests that measure performance on these tasks. Then, they can conduct experiments by comparing the performance of patients that use cannabis to patients that don’t use cannabis.

There is strong and consistent evidence that both short- and long-term cannabis use impairs verbal learning and memory. Effects on other types of memory such as working memory are less clear. Some studies suggest this is due to THC, and at least one study suggests CBD may protect against this side effect.

There is also strong evidence that cannabis impairs attention. Studies show that the younger an individual is when he or she begins consuming cannabis the poorer they will perform on attention-related tasks.

The motor function may also be impaired by cannabis, but only in the short-term.

As for the other cognitive domains, the effects of cannabis remain unclear. Some studies find that cannabis impairs cognitive function in every domain, but other studies refute these findings or have mixed results.

To summarize, there is plenty of evidence that cannabis use impairs memory and attention in the short term and that chronic heavy use impairs memory. However, it is unclear whether these effects persist with abstinence from cannabis.

For an in-depth review of scientific evidence on this topic see the article published in the journal of Biological Psychiatry titled: “Acute and Chronic Effects of Cannabinoids on Human Cognition—A Systematic Review.”