Marijuana Abuse

Marijuana is the herbal form of cannabis, a product of the plant cannabis sativa; hashish is the resinous form of the same plant. The primary active compound in cannabis is THC (tetrahydrocannabinol), which has psychoactive and physical effects when smoked or ingested. According to the World Health Organization, cannabis is the most widely cultivated, trafficked and abused illicit drug in the world: cannabis seizures have occurred in almost every country in the world and constitute about half of all drug seizures worldwide, and about 147 million people, or 2.5 percent of the world's population, are estimated to use cannabis annually.

Acute effects of marijuana use include impairment of cognitive processes and psychomotor performance. Cognitive effects include decreased ability to learn and recall new material, while psychomotor effects include impaired motor coordination and divided attention. Operation of complex machinery such as automobiles can be impaired for 24 hours following consumption of 20 mg of THC. Chronic effects of cannabis use include impairment of cognitive functioning which may not recover with cessation of use, injury to the airway, trachea and bronchi, reduced ability to fight off pulmonary infections, and chronic bronchitis; cannabis use during pregnancy is a risk factor for low birth weight and impaired fetal development.

Research into the use and abuse of marijuana is complicated by several facts. One is that in countries such as the United States where marijuana use is illegal, it is not possible to know the extent of usage [Page 1069]by people who do not come into contact with health or legal authorities concerning their marijuana use, and people may be reluctant to report illegal behavior on surveys.

Acute effects of marijuana use include impairment of cognitive processes and psychomotor performance.

On the other hand, in countries where marijuana use is not illegal, determining how many people use marijuana or how frequently it is used is not necessarily a high priority. In addition, tracking marijuana usage is not a high priority in many developing countries who have greater health concerns to deal with.

A third problem is that definitions of “abuse” vary widely: some people believe that any use of marijuana constitutes abuse, and many large-scale surveys report only use/nonuse. However, some organizations have developed criteria for different levels of use or abuse, based on factors such as frequency of use and/or negative medical or social effects for the user. For instance, the Diagnostic and Statistical Manual of Mental Disorders, 4th edition (DSM-IV) published by the American Psychological Association defines marijuana dependence as compulsive use, increased tolerance, impaired control, and continuation of use despite negative physical or psychological consequences. Marijuana abuse is defined by DSM-IV requires repeated instances of use under hazardous conditions, legal problems related to marijuana use, or clinically meaning impairment in social, occupational or educational functioning.

Compton and colleagues found no significant change in the increase of marijuana use in the United States in 1991–92 and 2001–02, either overall or among males, females, whites, Blacks or Hispanics; however significant increases were seen among 18-to-29-year-old Black and Hispanic women. Using the DSM-IV definitions, they found that marijuana abuse was more prevalent than marijuana dependence: the rate of abuse was 0.9 percent in 1991–92 and 1.1 percent in 2001–02, while the rate of dependence for those years were 0.3 percent and 0.4 percent, respectively. The proportions of abuse versus dependence were relatively consistent across age, sex, and racial/ethnic subgroups.

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