Cannabis and cognition

what is cognition?

Cognition refers to a collection of mental processes involved in carrying out everyday tasks and acquiring knowledge about the world. Cognitive processes and abilities are wide-ranging and include: perception, attention, motor skills, language, learning, memory, and executive functions such as problem-solving and decision making. Importantly, most tasks involve a combination of cognitive processes.

acute toxicity effects of cannabis on cognition

Acute cannabis use can affect a wide variety of cognitive processes. Most consistently, studies have shown acute cannabis use impairs verbal learning and memory, which refers to the ability to learn and remember verbal information, such as a list of words. Another relatively consistent finding following acute cannabis exposure is that of impaired response inhibition. Response inhibition refers to the ability to suppress or terminate a response that has been started but is no longer appropriate. The ability to stop an action that is no longer appropriate is very important in everyday life and failure to do so in some circumstances can result in very serious consequences, such as while driving.

Studies have also found following acute cannabis use, deficits in non-verbal memory tasks, working memory, decision-making, and other cognitive processes, though such findings are less consistent than those for verbal learning/memory and response inhibition. Acute cannabis exposure does not appear to significantly impair simpler cognitive tasks, such as simple reaction time measures, or verbal fluency measures.

chronic effects of cannabis use

Studies that have examined cognition in people who have been using cannabis for a while, typically find their performance on various tasks is somewhat impaired compared to people who have never used cannabis or who have never used it regularly. Such findings have led researchers to consider that maybe cannabis can have lasting effects on cognition, that is, outside the effects of intoxication.

The types of cognitive processes that have been found affected among regular users of cannabis are multiple and varied, ranging from verbal and non-verbal learning and memory deficits to decision-making and attention deficits. Many of these deficits appear to improve over time with continued abstinence from cannabis, while others do not. The more persistent deficits seem to be in the domain of verbal learning and memory and, for adolescents, also selective attention.

People who start using cannabis in adolescence appear to experience more persistent cognitive deficits. This has led researchers to consider the possibility that using cannabis while the brain is still developing might disrupt its development and cause long-lasting changes in brain function. Indeed, a number of studies have found a link between abnormal brain anatomy and an earlier age of first cannabis use. However, research looking at this issue is in its early stages and much more of it is needed before we may conclude whether or not cannabis use causes long-lasting brain changes.