Health & Fitness

Psychosis often the effect of long-term, recreational marijuana use

Diego was a 20-year-old college junior who was brought to the emergency room by the police. They were called by his resident advisor for bizarre behavior in the dormitory. Diego was anxious, frequently glancing around the room, and talked in a disorganized manner about the Illuminati, Freemasons and the end of the world.

A urine drug screen was positive for cannabis. When asked later during the hospitalization, his resident advisor reported Diego smoked marijuana daily, and Diego admitted to being a daily marijuana smoker since arriving at college.

Variants on the above scenario increasingly occur in emergency rooms and hospitals around the country. This has coincided with the growing use of recreational marijuana in youths and adults.

Dr. Stephen McLeod-Bryant.JPG
Dr. Stephen McLeod-Bryant is a clinical associate professor in the Department of Psychiatry and Behavioral Sciences at the University of Miami Miller School of Medicine.

Naturally, grown marijuana has several active ingredients, or cannabinoids, which can cause significant effects when inhaled or ingested. The main active compound in recreational marijuana (Cannabis sativa) is delta-9-tetrahydrocannabinol (D-9-THC). D-9-THC binds to cannabinoid receptors in the brain and other parts of the body to produce its effects. This system has complex interactions with other neurotransmitters in the brain that have been implicated in the dysfunction associated with psychoses.

Herbal or recreational marijuana is significantly different from medicinal marijuana which, by definition of Florida statute, is low (0.8 percent or less) in D-9-THC and 10 percent or more cannabidiol (or CBD), according to Florida law. A qualified physician may prescribe medicinal marijuana for a select list of qualified disorders including cancer, epilepsy, glaucoma, PTSD, and AIDS. However, research studies indicate that D-9-THC in recreational marijuana produces, in a dose-dependent fashion (i.e., the higher the dose, the more dysfunction), short-term memory impairment and a distorted perception of time.

This is in addition to its ability to reduce anxiety and increase sedation. Ten milligrams of D-9-THC has been shown to produce transient psychotic symptoms, increased anxiety, intoxication, and sedation in healthy volunteers.

People using recreational marijuana today are ingesting higher doses than those using the substance in previous decades. It is estimated that the average concentration of D-9-THC in recreational marijuana was 3 percent or less in the 1960s, but is at least 14 percent now because of the knowledge as to how to grow a more potent product.

Nearly a dozen studies done in the United States, Europe, and Australia have shown that the heavier and the longer the use of recreational marijuana, the greater the risk of psychosis. Taken together, the risk of psychosis is four times higher in the heavy users when compared to non-users. Use beginning before the age of 18, daily use, use of higher potency forms (e.g., ingesting resins rather than smoking the plant), and using synthetic forms (e.g., Spice) have been associated with increased risk. There is some indication that genetic variation may predispose an individual to increased risk of psychosis, but the specific relationship remains to be determined.

When psychosis is associated with D-9-THC use, it can occur acutely during intoxication with resolution occurring once the "high" passes. However, a brief psychosis may linger hours to days after intoxication has passed. Finally, it appears a prolonged psychosis (e.g., schizophrenia) may persist long after the intoxication has worn off.

All of these psychoses may require treatment because of the frightening nature of the experience to the user or to their family and friends. Prevention of future episodes is greatly enhanced by avoiding herbal marijuana or other drugs associated with psychosis such as methamphetamine.

Dr. Stephen McLeod-Bryant is a clinical associate professor in the Department of Psychiatry and Behavioral Sciences at the University of Miami Miller School of Medicine. For more information, visit or call 305-355-9028.