How Does Marijuana Affect the Brain?

THC acts upon specific sites in the brain, called cannabinoid receptors, kicking off a series of cellular reactions that ultimately lead to the “high” that users experience when they smoke marijuana. Some brain areas have many cannabinoid receptors; others have few or none. The highest density of cannabinoid receptors are found in parts of the brain that influence pleasure, memory, thoughts, concentration, sensory and time perception, and coordinated movement.

Not surprisingly, marijuana intoxication can cause distorted perceptions, impaired coordination, difficulty in thinking and problem solving, and problems with learning and memory. Research has shown that marijuana’s adverse impact on learning and memory can last for days or weeks after the acute effects of the drug wear off. As a result, someone who smokes marijuana every day may be functioning at a suboptimal intellectual level all of the time. Research clearly demonstrates that marijuana has the potential to cause problems in daily life or make a person’s existing problems worse.

What Treatment Options Exist?

Behavioral interventions, including cognitive behavioral therapy and motivational incentives (i.e., providing vouchers for goods or services to patients who remain abstinent) have shown efficacy in treating marijuana dependence. Although no medications are currently available, recent discoveries about the workings of the cannabinoid system offer promise for the development of medications to ease withdrawal, block the intoxicating effects of marijuana, and prevent relapse.

The latest treatment data indicate that marijuana was the most common illicit drug of abuse and was responsible for about 16 percent (289,988) of all admissions to treatment facilities in the United States. Marijuana admissions were primarily male (73.8 percent), White (51.5 percent), and young (36.1 percent were in the 15–19 age range). Those in treatment for primary marijuana abuse had begun use at an early age: 56.2 percent had abused it by age 14 and 92.5 percent had abused it by age 18.