Hockenbury Discovering Psychology 5th txtbk

Psychoactive Drugs165Psychoactive DrugsKey Theme• Psychoactive drugs alter consciousness by changing arousal, mood,thinking, sensations, and perceptions.Key Questions• What are four broad categories of psychoactive drugs?• What are some common properties of psychoactive drugs?• What factors influence the effects, use, and abuse of drugs?Psychoactive drugs are chemical substances that can alter arousal, mood, thinking,sensation, and perception. In this section, we will look at the characteristics of fourbroad categories of psychoactive drugs:1. Depressants—drugs that depress, or inhibit, brain activity2. Opiates—drugs that are chemically similar to morphine and that relieve pain andproduce euphoria3. Stimulants—drugs that stimulate, or excite, brain activity4. Psychedelic drugs—drugs that distort sensory perceptionspsychoactive drugA drug that alters consciousness, perception,mood, and behavior.physical dependenceA condition in which a person has physicallyadapted to a drug so that he or she musttake the drug regularly in order to avoidwithdrawal symptoms.drug toleranceA condition in which increasing amounts ofa physically addictive drug are needed toproduce the original, desired effect.withdrawal symptomsUnpleasant physical reactions, combinedwith intense drug cravings, that occur whena person abstains from a drug on which heor she is physically dependent.drug rebound effectWithdrawal symptoms that are the oppositeof a physically addictive drug’s action.Common Properties of Psychoactive DrugsAddiction is a broad term that refers to a condition in which a person feels psychologicallyand physically compelled to take a specific drug. People experience physicaldependence when their body and brain chemistry have physically adapted to a drug.Many physically addictive drugs gradually produce drug tolerance, which means thatincreasing amounts of the drug are needed to gain the original, desired effect.When a person becomes physically dependent on a drug, abstaining from the drugproduces withdrawal symptoms. Withdrawal symptoms are unpleasant physical reactionsto the lack of the drug, plus an intense craving for it. Withdrawal symptoms are alleviatedby taking the drug again. Often, the withdrawal symptoms are opposite to thedrug’s action, a phenomenon called the drug rebound effect. For example, withdrawingfrom stimulating drugs, like the caffeine in coffee, may produce depression and fatigue.Withdrawal from depressant drugs, such as alcohol, may produce excitability.Each psychoactive drug has a distinct biological effect. Psychoactive drugs may influencemany different bodily systems, but their consciousness-altering effects are primarilydue to their effect on the brain. Typically, these drugs influence brain activityby altering synaptic transmission among neurons. As we discussed in Chapter 2,drugs affect synaptic transmission by increasing or decreasing neurotransmitteramounts or by blocking, mimicking, or influencing a particular neurotransmitter’seffects (see Figure 2.6). Chronic drug use can also produce long-term changesin brain structures and functions, as discussed in the Focus on Neuroscience on thenext page.The biological effects of a drug can vary considerably from person to person. An individual’srace, gender, age, and weight may influence the intensity of a particular drug’seffects. For example, many Asians and Asian Americans have a specific geneticvariation that makes them much more responsive to alcohol’s effects. Inturn, this heightened sensitivity to alcohol is associated with significantlylower rates of alcohol dependence seen among people of Asian heritage ascompared to other races (Cook & others, 2005; Kufahl & others, 2008).Psychological and environmental factors can also influence a drug’s effects.An individual’s response to a drug can be greatly affected by his orher personality characteristics, mood, expectations, experience with thedrug, and the setting in which the drug is taken (Blume & others, 2003;Kufahl & others, 2008).“At this point, we know it’s addictive.”© The New Yorker Collection.Cartoonbank.com. All rights reserved.