Marijuana consumption and tolerance to physiological and subjective effects

Area of Science:

• Pharmacology
• Cannabis Research

Background:

• Understanding the relationship between marijuana use and tolerance is crucial for public health and clinical practice.
• Previous research has yielded mixed results regarding tolerance development to cannabis.

Purpose of the Study:

• To investigate the development of tolerance to marijuana's effects in individuals with a history of moderate or heavy use.
• To determine if increased consumption correlates with tolerance to delta-9 tetrahydrocannabinol (THC).

Main Methods:

• A 31-day study involving volunteers with prior marijuana use.
• Participants self-administered one-gram marijuana cigarettes (2.1% delta-9 THC) daily for 21 days.
• Consumption, intoxication ratings, and physiological effects (pulse rate) were monitored.

Main Results:

• Both moderate and heavy users increased their marijuana consumption.
• Heavy users (5.7 cigarettes/day) showed decreased intoxication and shorter pulse rate effects, indicating tolerance.
• Moderate users (3.2 cigarettes/day) did not exhibit significant changes in these responses.

Conclusions:

• Tolerance to key marijuana intoxication effects develops only with repeated, heavy self-administration of delta-9 THC.
• Increased marijuana consumption during the study period was not necessarily linked to the development of tolerance.