Dependence on marijuana by chronic, heavy users, or by persons predisposed to addictive behaviors is a potential development. Although psychological dependency can result in behaviors similar to those found in actual biochemical addiction, cannabis dependency rarely manifests in ways overtly harmful to the subject’s life or life-style. Psychological dependence on any mind-altering substance may be caused by an underlying depression or by psychological turmoil. According to the Institute of Medicine (IOM), “Risk factors for marijuana dependence are similar to those for other forms of substance abuse.” However, those persons at risk for developing a psychological dependence to cannabinoids face a lesser threat than with other drugs. The IOM study also noted, “Animal research demonstrates the potential for dependence, but this potential is observed under a narrow range of conditions than with benzodiazepines (such as Valium), opiates, cocaine, or nicotine.”
Although epidemiological surveys show that cannabis dependence is the most common form of drug dependence due to its widespread availability, relatively few users voluntarily seek treatment for marijuana dependence, according to the American Psychiatric Association in 1994. While a small percentage of the population may be prine to substance abuse, evidence suggests that the vast majority of marijuana users have discontinued their use on a voluntary basis.
Patients who regularly use any medication may be labeled as medically dependant on that medication’s beneficial effects. Prohibitionists who reject the use of marijuana as a medicine may purposely misinterpret reasonable medical dependence as psychological dependence simply because cannabis is an illicit medication.
Some chronic users report withdrawal symptoms after abrupt cessation. These symptoms, characterized by irritability, agitation, sleep disorder, hyperhidrosis, and loss of appetite, are generally mild. Cannabis dependency is less determined by physical than by psychological factors. Dependency and abuse potential of therapeutically employed delta-9-THC is low.
In a German study of 1,458 current or previous cannabis users, 2 to 10 percent of the solely cannabis users were classified as substance dependent. If those who also used other illegal drugs were included, 8 percent of cannabis users were regarded as dependent, including 1 percent of the “occasional users,” 7 percent of the “individual users,” 10 percent of the “recreational users,” and 28 percent of the “permanent users.” Duration of consumption had no influence on the likelihood of the subject to quit use, an indication that the risk of dependency was independent of duration of use. 
Related sections: Addiction, Antimotivational Syndrome, Depression.
 Institute of Medicine, Marijuana and Medicine: Assessing the Science Base. Executive Summary, Washington DC: National Academy Press, 1999
 Institute of Medicine, op. cit.
 World Health Organization Project on Health Implications of Cannabis Use, 1997
 Zimmer and Morgan, Marijuana Myths: Marijuana Facts. New York: The Lindesmith Center, 1997
 Grotenhermen, “Review of Unwanted Actions of Cannabis and THC.” Chapter 2, p. 237-238