Rats with naturally high levels of stress were significantly more likely to self-use cannabis when made available to them. Behavioral tests showed that pre-experiment stress hormone levels were the strongest predictor of cannabis-seeking behavior. Increased use of cannabis was also associated with lower cognitive flexibility, i.e. the ability to adapt to new situations. Another factor was low levels of endocannabinoids, which are natural substances in the body that regulate various biological functions, including mood and stress. These findings suggest that the combination of high stress, reduced cognitive flexibility, and low endocannabinoid activity may be an early indicator of vulnerability to cannabis abuse. The results of the study help to better understand the mechanisms why stressed individuals repeatedly return to the use of this drug. Such knowledge may be important in the prevention and treatment of cannabis addiction.