Marijuana Dependence

Definition

Cannabis, more commonly called marijuana, refers to the several varieties of Cannabis sativa, or Indian hemp plant, that contains the psychoactive drug delta-9-tetrahydrocannabinol (THC). Cannabis-related disorders refer to problems associated with the use of substances derived from this plant.

Symptoms

CANNABIS DEPENDENCE AND ABUSE. The handbook used by mental health professionals to diagnose mental disorders is the Diagnostic and Statistical Manual of Mental Disorders, also known as the DSM-IV-TR. This manual states that the central features of cannabis dependence are compulsive use, tolerance of its effects, and withdrawal symptoms. Use may interfere with family, school, and work, and may cause legal problems.

Regular cannabis smokers may show many of the same respiratory symptoms as tobacco smokers. These include daily cough and phlegm, chronic bronchitis, and more frequent chest colds. Continued use can lead to abnormal functioning of the lung tissue, which may be injured or destroyed by the cannabis smoke.

Recent research indicates that smoking marijuana has the potential to cause severe increases in heart rate and blood pressure, particularly if combined with cocaine use. Even with marijuana use alone, however, the heart rate of subjects increased an average of 29 beats per minute when smoking marijuana.

A study of heavy marijuana users has shown that critical skills related to attention, memory, and learning can be impaired, even after use is discontinued for at least 24 hours. Heavy users, compared to light users, made more errors on tasks and had more difficulty sustaining attention and shifting attention when required. They also had more difficulty in registering, processing, and using information. These findings suggest that the greater impairment in mental functioning among heavy users is most likely due to an alteration of brain activity directly produced by the marijuana use.

Recent studies have found that babies born to mothers who used marijuana during pregnancy were smaller than those born to nonusing mothers. Smaller babies are more likely to develop health problems. Additionally, nursing mothers who use marijuana pass some of the THC to the baby in their breast milk. Research shows that use of marijuana during the first month of breastfeeding can impair an infant's motor development.

Cannabis abuse is characterized by less frequent use and less severe problems. However, as with cannabis dependence, abuse can interfere with performance at school or work, cause legal problems, and interfere with motor activities such as driving or operating machinery.

CANNABIS INTOXICATION. Cannabis intoxication refers to the occurrence of problematic behaviors or psychological changes that develop during, or shortly after, cannabis use. Intoxication usually starts with a "high" feeling followed by euphoria, inappropriate laughter, and feelings of grandiosity. Other symptoms include sedation, lethargy, impaired short-term memory, difficulty with motor tasks, impaired judgment, distorted sensory perceptions, and the feeling that time is passing unusually slowly. Sometimes severe anxiety, feelings of depression, or social withdrawal may occur. Along with these symptoms, common signs of cannabis intoxication include reddening of the membranes around the eyes, increased appetite, dry mouth, and increased heart rate.