Delta 9-tetrahydrocannabinol (THC) is the primary psychoactive constituent of the cannabis sativa plant and is believed to be primarily responsible for the cognitive effects and the addictive potential of smoked cannabis. THC intoxication has been shown to impair cognitive function on a number of levels—from basic motor coordination to more complex tasks, such as the ability to plan, organize, solve problems, make decisions, remember, and control emotions and behavior.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3037578/#:~:text=THC%20intoxication%20has%20been%20shown,and%20control%20emotions%20and%20behavior.