How Is Marijuana Physically Addictive?

Dependence

A debate lingers as to whether marijuana is physically addictive. It's difficult to classify it as a physical addition. But heavy marijuana use has been known to lead to psychological addiction and social dependence, according to the Center for Substance Abuse Research at the University of Maryland. Users don't often show signs of addiction or withdrawal, but people who want to quit using marijuana do seek some kind of treatment through clinics or support groups, much like alcoholism. People who begin to crave marijuana may think about the drug all of the time and where to get it. Some smokers may need more marijuana to feel the same effect and find themselves always lighting up. Admission to rehabilitation facilities for marijuana addiction has increased in recent years, and the product has been getting more powerful, according to Marijuana Addiction, the information website for Spencer Recovery Centers. Some believe heavy marijuana use can cause the body to seek more of the drug.

Receptors

A study of monkeys showed that the subjects began injecting themselves with THC, the active chemical in marijuana, in the same way they seek out cocaine or morphine, it was reported in New Scientist on Oct. 16, 2000. Researchers at the National Institute on Drug Abuse (NIDA) in Baltimore gave the squirrel monkeys small injections of THC through a lever that the monkeys pressed. The lab animals soon learned how to administer the drug themselves and were taking up to 30 injections an hour. When the monkeys were given a drug that blocked brain receptors for cannabis, the animals stopped pressing the lever. Many people say more studies on humans are needed. They aren't convinced that it is physically addictive and say most people can quit the drug with a few days of discomfort, viewing it as a habit instead of an addiction.

Brain Changes

The NIDA says long-term marijuana use can lead to addiction but refers to it as compulsive drug seeking and abuse, as long-term use has harmful effects in social functioning. Irritability, sleeplessness, decreased appetite, anxiety and drug cravings are reported by long-term marijuana users who try to quit. It takes about a week or two for withdrawal symptoms to subside. Research has shown changes in the brain similar to those seen in other major drug addictions, according to NIDA. Marijuana withdrawal in lab animals led to an increase in the activity of stress nerve cells and changes to dopamine neurons involved in all drugs of abuse. NIDA notes that research in the Archives of General Psychiatry in 2001 showed marijuana's adverse impact on learning and memory can last for days or weeks--even after the effects of the drug wear off--because of its physical presence.