Hockenbury Discovering Psychology 5th txtbk

Psychoactive Drugs175MarijuanaThe common hemp plant, Cannabis sativa, is used to make ropeand cloth. But when its leaves, stems, flowers, and seeds are driedand crushed, the mixture is called marijuana, one of the mostwidely used illegal drugs. Marijuana’s active ingredient is thechemical tetrahydrocannabinol, abbreviated THC. When marijuanais smoked, THC reaches the brain in less than 30 seconds.One potent form of marijuana, hashish, is made from the resin ofthe hemp plant. Hashish is sometimes eaten.To lump marijuana with the highly psychedelic drugs mescalineand LSD is somewhat misleading. At high doses, marijuana cansometimes produce sensory distortions that resemble a mild psychedelicexperience. Low to moderate doses of THC typically producea sense of well-being, mild euphoria, and a dreamy state of relaxation.Senses become more focused and sensations more vivid. Taste,touch, and smell may be enhanced; time perception may be altered.In the early 1990s, researchers discovered receptor sites in the brain that arespecific for THC. They also discovered a naturally occurring brain chemical, calledanandamide, that is structurally similar to THC and that binds to the THCreceptors in the brain (Devane & others, 1992). Anandamide appears to be involvedin regulating the transmission of pain signals and may reduce painful sensations.Researchers also suspect that anandamide may be involved in mood and memory.Marijuana and its active ingredient, THC, have been shown to be helpful in the treatmentof pain, epilepsy, hypertension, nausea, glaucoma, and asthma (Piomelli, 2003). Incancer patients, THC can prevent the nausea and vomiting caused by chemotherapy.However, the medical use of marijuana is limited and politically controversial.On the negative side, marijuana interferes with muscle coordination and perceptionand may impair driving ability. When marijuana and alcohol use are combined,marijuana’s effects are intensified—a dangerous combination for drivers. Marijuanahas also been shown to interfere with learning, memory, and cognitive functioning(Harvey & others, 2007).There are very few THC receptors in the brainstem, the part of the brain thatcontrols such life-support functions as breathing and heartbeat. Thus, high doses ofTHC do not interfere with respiratory and cardiac functions as depressants and opiatesdo (Piomelli, 2003).Most marijuana users do not develop tolerance or physical dependence. Chronicusers of high doses can develop some tolerance to THC and may experience withdrawalsymptoms when its use is discontinued (Budney & others, 2007; Nocon &others, 2006). Such symptoms include irritability, restlessness, insomnia, tremors,and decreased appetite.Medical Marijuana The medical use ofmarijuana can be traced back for thousandsof years to ancient China, Egypt,India, and Greece, among other countries.Its use was legal in the United States until1937, when marijuana was outlawed, despiteprotests from the American MedicalAssociation (Aggarwal & others, 2009).Research into the possible medical benefitsof marijuana continued, however, and in1996 California became the first state tolegalize the medical use of marijuana.Now, people with a physician’s referraland a state-issued ID card can legally purchasemedical-grade marijuana at one ofhundreds of California dispensaries, likethe San Francisco dispensary shown here.Marijuana can relieve certain types ofchronic pain, inflammation, muscle spasms,nausea, vomiting, and other symptomscaused by such illnesses as multiple sclerosis,cancer, and AIDS (see Pisanti & others,2009; Rahn & Hohmann, 2009). Twelveother states have legalized medical marijuana;similar legislation is pending in severalother states.Designer “Club” DrugsEcstasy and the Dissociative Anesthetic DrugsSome drugs don’t fit into neat categories. The “club drugs” are a loose collectionof psychoactive drugs that are popular at dance clubs, parties, and the all-nightdance parties called “raves.” Many of these drugs are designer drugs, meaning thatthey were synthesized in a laboratory rather than derived from naturally occurringcompounds. In this section, we’ll take a look at three of the most popular clubdrugs—ecstasy, ketamine, and PCP.The initials MDMA stand for the long chemical name of the quintessential clubdrug better known as ecstasy. Other street names are X, XTC, Adam, and the “lovedrug.” Ecstasy was developed by a German pharmaceutical company in 1912 forpossible use as an appetite suppressant, but it was not tested on humans until the1970s. Structurally similar to both mescaline and amphetamine, MDMA has stimulantand psychedelic effects.marijuanaA psychoactive drug derived from the hempplant.MDMA or ecstasySynthetic club drug that combines stimulantand mild psychedelic effects.