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Chapter 12


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University of Toronto Scarborough
Konstantine Zakzanis

Chapter 12: Substance-Related Disorders • The pathological use of substances falls into two categories: substance abuse and substance dependence. Substance dependence is characterized by DSM-IV-TR as the presence of at least three of the following: ­ The person develops tolerance, indicated by either (1) larger doses of the substance being needed to produce the desire effect or (2) the effects of the drug becoming markedly less if the usual amount is taken. ­ Withdrawal symptoms – negative physical and psychological effects – develop when the person stops taking the substance or reduce the amount. ­ The person uses more the substance or uses it for a longer time than intended. ­ The person recognizes excessive use of the substance; he or she may have tried to reduce usage but has been unable to do so. ­ Much of the person’s time in spent in efforts to obtain the substance or recover from its effects. ­ Substance use continues despite psychological or physical problems caused or exacerbated by the drug. ­ The person gives up or cuts back a participation in many activities (work, recreation, socializing) because of the use of the substance. • For the less serious diagnosis of substance abuse, the person must experience one of the following as a result of recurrent use of the drug: ­ Failure to fulfill major obligations ­ Exposure to physical dangers ­ Legal problems ­ Persistent social or interpersonal problems. • Substance intoxication is diagnosed when the ingestion of substance affects the central nervous system and produces maladaptive cognitive and behavioural effects. Alcohol Abuse and Dependence • The term abuse is often used to refer to both aspects of the excessive and harmful use of alcohol. • Some research suggests that tolerance results from changes in the number of sensitivity of GABA or glutamate receptors. • The person who abuses alcohol, in contrast to the person physically dependent on it, experiences negative social and occupational effects from the drug but does not show tolerance, withdrawal, or the compulsive drinking patterns seen in the person who is alcohol dependent. • Alcohol abuse or dependence is often part of polydrug (or polysubstance) abuse, using or abusing more than one drug at a time. Short-Term Effects of Alcohol • Because drinking alcoholic beverages is accepted in most societies, alcohol is rarely regarded as a drug. But it is indeed a drug, and it has a biphasic effect. This means that the initial effect of alcohol is stimulating – the drinker experiences an expansive feeling of sociability and well-being as the blood-alcohol level rises – but after the blood-alcohol level peaks and begins to decline, alcohol acts as a depressant that may lead to negative emotion. • It stimulates GABA receptors, which may be responsible for reducing tension. • Alcohol also increases levels of serotonin and dopamine, and this may be the source of its ability to produce pleasurable effects. Finally, alcohol inhibits glutamate receptors, which may cause the cognitive effects of alcohol intoxication, such as slurred speech and memory loss. Long-Term Effects of Prolonged Alcohol Abuse • Prolonged alcohol use with reduction in the intake of proteins contributes to the development of cirrhosis of the liver, a potentially fatal disease in which some liver cells become engorged with fat and protein, impeding their function; some cells die, triggering an inflammatory process. When scar tissue develops, blood flow is obstructed. • Heavy alcohol consumption during pregnancy is the leading cause of mental retardation. The growth of the fetus is slowed, and cranial, facial, and limb anomalies are produced, a condition known as fetal alcohol syndrome (FAS). • French paradox: despite diets rich in saturated fats, the French have relatively low cholesterol levels. Some hypothesize that consumption of low to moderate amounts of red wine may lower cholesterol levels. Nicotine and Cigarette Smoking • Nicotine is the addicting agent of tobacco. It stimulates receptors, called nicotinic receptors, in the brain. Molecular biology studies suggest that the main receptor mediating nicotine dependence is the nicotinic acetylcholine receptor subtype. • Female smokers have substantially greater changes in cognitive activity after nicotine exposure. Consequences of Second-Hand Smoke • The smoke coming from the burning end of a cigarette, so-called second- hand smoke, or environmental tobacco smoke (ETS), contains higher concentrations of ammonia, carbon monoxide, nicotine, and tar than does the smoke actually inhaled. Marijuana • Marijuana consists of the dried and crushed leaves and flowering tops of the hemp plant, Cannabis sativa. It is most often smoked, but it may be chewed, prepared as a tea, or eaten in bakes goods. Hashish, much stronger than marijuana, is produced by removing and drying the resin exudate of the tops of high-quality cannabis plants. Effects of Marijuana Psychological Effects • The major active chemical in marijuana is delta-9-tetradyrocannabinol (THC) Somatic Effects • The CB receptors in the brain are located in various regions, and it is believed that receptors in the hippocampus account for the short-term memory loss that sometimes follows smoking marijuana. • The short-term side effects of marijuana include blood-shot and itchy eyes, dry mouth and throat, increased appetite, reduced pressure within the eye, and somewhat raised blood pressure. • One marijuana cigarette is the equivalent of four tobacco cigarettes in tar intake, five in carbon monoxide intake, and 10 in terms of damage to cells lining the airway. • Reverse tolerance is the direct opposite of the tolerance that occurs with an addicting drug, such a heroin. The substance THC, after being rapidly metabolized, is stored in the body’s fatty tissue and then released very slowly, perhaps for a month, which may explain reverse tolerance for it. Therapeutic Effects • THC and related drugs can reduce the nausea and loss of appetite that accompany chemotherapy for some cancer patients. • Marijuana is also a treatment for the discomfort of AIDS, as well as glaucoma, epilepsy, and multiple sclerosis. Sedative and Stimulants • Addiction to drugs, including sedatives, was disapproved of but tolerated in the U.S until 1914, where the Harrison Narcotics Act made the unauthorized use of various drugs illegal and those addicted to them criminals. The drugs we discus here, some of which may be obtained legally with prescription, can be divided into two general categories: sedative and stimulants. Sedatives: • The major sedatives, often called downers, slow the activities of the body and reduce is responsiveness. This group of drugs includes the opiates- opium and its derivatives, morphine, heroin, and codeine – and the synthetic barbiturates and tranquilizers, such as secobarbital (Seconal) and diazepam. Opiates • The opiates are a group of addictive sedatives that relieve pain and induce sleep when taken in moderate doses. • Opium: One of the opiates, the dried, milky juice obtained from the immature fruit of the opium poppy. This addictive narcotic produces euphoria and drowsiness and reduces pain. • In 1806, the alkaloid morphine, named after Morpheus, the Geek god of dreams, was separated from raw opium. This bitter –tasting powder proved to be a powerful sedative and pain reliever. • In 1874, they found that morphine could be converted into another powerful pain-relieving drug, which they named heroin. Used initially as a cure for morphine addiction, heroin was substituted for morphine in cough syrups and other patent medicines. Psychological and Physical Effects • Opium and its derivatives, morphine and heroin, produce euphoria, drowsiness, reverie, and a lack of coordination. Heroin has an additional initial effect: the rush, feeling of warm, suffusing ecstasy immediately following an intravenous injection. • Opiates produce their affects by stimulating neural receptors of the body’s own opioid system. Heroin, for example, is converted into morphine in the brain, and then binds to opioid receptors. The body produces opioids, called endorphins and enkephalins, and opium and its derivatives fit into their receptors and stimulate them. Synthetic Sedatives • Barbiturates, another major type of sedative, were synthesized as aids for sleeping and relaxation. • Sedatives relax the muscles, reduce anxiety, and in small doses produce a mildly euphoric state. Like alcohol, they are thought to produce these psychological effects by stimulating the GABA system. With excessive doses, however, speech becomes slurred and gait unsteady. Judgement, concentration, and ability to work may be severely impaired. Stimulants • Stimulants or uppers such as cocaine, act on the brain and the sympathetic nervous system to increase alertness and motor activity. Amphetamines • Chen isolated an alkaloid from this plant belonging to the genus Ephedra, and the result, ephedrine, proved highly successful in treating asthma. But relying on the shrub for the drug was not efficient, and so efforts to develop a synthetic substitute began. Amphetamines resulted from these efforts. • The first amphetamine, Benzedrine was synthesized in 1927. Almost as soon as it became commercially available in the early 1930s as an inhalant to relieve stuffy noses, the public discovered its stimulating effects. Physicians thereafter prescribed it and the other amphetamines that were soon synthesized to control mild depression and appetite. Soldiers on both sides in the Second World War were supplied with the rugs to ward off fatigue, and today amphetamines are sometimes used to treat hyperactive children. • Amphetamines, such as Benzedrine, Dexedrine, and Methedrine, produce their effects by causing the release of norepinephrine and dopamine and blocking the reuptake of these neurotransmitters. • As tolerance increases, the user may stop taking pills and inject Methedrine, the strongest of the amphetamines, directly into the veins. Cocaine • The alka
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