Stimulants

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Psychoactive Drugs
DRINKING AND DRIVING DON’T MIX
Though practice makes it seem easy, driving a car is a complex informationprocessing task. As described in the
chapter on thought, language, and intelligence, such tasks require constant vigilance, quick decisions, and skillful
execution of responses. Alcohol can impair all these processes, as well as the
ability to judge the degree of impairment—thus making drinking and driving
a deadly combination that results in
275,000 injuries and almost 17,000 deaths
each year in the United States alone
(McDonald, Wang, & Camargo, 2004;
National Highway Traffic Safety Administration, 2005).
predisposition toward alcohol dependence (Agarwal, 1997; Enoch, 2003), though the
genes involved have not yet been identified (Holden, 1998). Other groups (the Japanese,
for example) may have inherited metabolic characteristics that enhance alcohol’s adverse
effects, possibly inhibiting the development of alcohol abuse (Iwahashi et al., 1995).
Barbiturates Sometimes called “downers” or sleeping pills, barbiturates are highly
addictive. In small doses, their psychoactive effects include relaxation, mild pleasure,
loss of muscle coordination, and lowered attention. Higher doses cause deep sleep, but
continued use actually distorts sleep patterns (Kales & Kales, 1973). So long-term use
of barbiturates as sleeping pills may be unwise. Overdoses can be fatal. Withdrawal
symptoms are among the most severe for any drug and can include intense agitation,
violent outbursts, seizures, hallucinations, and even sudden death.
Gamma hydroxybutyrate (GHB) is a naturally occurring substance similar to the
neurotransmitter GABA (Wong, Gibson, & Snead, 2004). In recent years, a laboratorymanufactured version of GHB (also known as “G”) has become a popular “club drug”
known for creating relaxation, feelings of elation, loss of inhibitions, and increased sex
drive. Unfortunately, it can also cause nausea and vomiting, headaches, memory loss,
dizziness, loss of muscle control or paralysis, breathing problems, loss of consciousness,
and even death—especially when combined with alcohol or other drugs (Miotto et al.,
2001; Stillwell, 2002). As with other depressants, long-term use of GHB can lead to
dependence. If dependent users abruptly stop taking the drug, they may experience a
withdrawal syndrome that can include seizures, hallucinations, agitation, coma, or
death (Tarabar & Nelson, 2004).
GHB
Stimulants
Whereas depressants slow down central nervous system activity, stimulants speed it
up. Amphetamines, cocaine, caffeine, and nicotine are all examples of stimulants.
stimulants Psychoactive drugs that increase behavioral and mental activity.
Amphetamines Often called “uppers” or “speed,” amphetamines increase the release
of norepinephrine and dopamine into synapses, affecting sleep, learning, and mood
(Bonci et al., 2003; Kolb et al., 2003). Amphetamines also slow the removal of both
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Chapter 4 Consciousness
substances at synapses, leaving more of them there, ready to work. The increased activity at these neurotransmitters’ receptors results in alertness, arousal, and appetite suppression. These effects are amplified by the fact that amphetamines also reduce activity of the inhibitory neurotransmitter GABA (Centonze et al., 2002). Amphetamines’
rewarding properties are probably associated with their effect on dopamine activity,
because taking dopamine antagonists reduces amphetamine use (Holman, 1994).
People who abuse amphetamines usually begin taking these drugs in an effort to
lose weight, stay awake, or “get high.” Continued use leads to anxiety, insomnia, heart
problems, brain damage, movement disorders, confusion, paranoia, nonstop talking,
and psychological and physical dependence (Thompson et al., 2004; Volkow et al.,
2001). In some cases, the symptoms of amphetamine abuse are almost identical to those
of paranoid schizophrenia, a serious mental disorder linked to dopamine malfunction.
Like amphetamines, cocaine increases norepinephrine and dopamine activity and decreases GABA activity, so it produces many amphetamine-like effects (Kolb et al.,
2003). Cocaine’s particularly powerful and rapid effect on dopamine activity may underlie its remarkably addictive nature (Bonci et al., 2003; Ciccocioppo et al., 2004; Ungless
et al., 2001). In fact, most drugs with rapid onset and short duration are more addictive than others (Kato, Wakasa, & Yamagita, 1987), which helps explain why crack—a
purified, fast-acting, highly potent, smokable form of cocaine—is especially addictive.
Cocaine stimulates self-confidence, a sense of well-being, and optimism. Continued
use, though, brings nausea, overactivity, insomnia, paranoia, a sudden depressive
“crash,” hallucinations, sexual dysfunction, and seizures (Lacayo, 1995). Overdoses,
especially overdoses of crack cocaine, can be deadly. Even small doses can cause a fatal
heart attack or stroke (Klausner & Lewandowski, 2002; Marzuk et al., 1995). Using
cocaine during pregnancy harms the fetus (e.g., Hurt et al., 1995). However, many of
the severe, long-term behavioral problems seen in “cocaine babies” may have as much
to do with poverty and neglect after birth as with the mother’s cocaine use beforehand.
Early intervention can reduce the effects of both cocaine and the hostile environment
that confronts most cocaine babies (Mayes et al., 2003; Singer et al., 2004; Wren, 1998).
Cocaine
John Entwistle,
bass player for The Who, died of a
cocaine-related heart attack in 2002. He
joined a long list of celebrities (including
Chris Farley and Righteous Brother Bobby
Hatfield) and an even longer list of ordinary people whose lives have been destroyed by the abuse of cocaine or other
drugs.
DEADLY DRUG USE
Caffeine may be the world’s most popular drug. It is found not only in coffee and tea but also in chocolate and many soft drinks. Caffeine reduces drowsiness and
can enhance cognitive performance, including problem solving and vigilance (Beaumont
et al., 2001). It also increases the capacity for physical work and raises urine production
(Warburton, 1995). At high doses it causes anxiety and tremors. People can develop tolerance to caffeine, and it can be physically addictive (Strain et al., 1994). Withdrawal
symptoms—including headache, fatigue, anxiety, shakiness, and craving—appear on the
first day of abstinence and last about a week (Silverman et al., 1992). Caffeine may make
it harder for women to become pregnant and may increase the risk of miscarriage or
stillbirth (Balat et al., 2003; Bech et al., 2005; Rasch, 2003; Wisborg et al., 2003). Moderate daily caffeine use may also cause slight increases in blood pressure (James, 2004),
but otherwise it appears to have few, if any, negative effects (Kleemola et al., 2000;
Winkelmayer et al., 2005).
Caffeine
Nicotine A powerful autonomic nervous system stimulant, nicotine is the main psychoactive ingredient in tobacco. It enhances the action of acetylcholine and increases
the availability of glutamate, the brain’s primary excitatory neurotransmitter. It also
activates the brain’s dopamine-related pleasure systems (Balfour, 2002; McGehee et al.,
1995). Nicotine has many psychoactive effects, including elevated mood and improved
memory and attention (Domino, 2003; Ernst et al., 2001). Like heroin and cocaine,
nicotine can be physically addictive (White, 1998). It doesn’t create the “rush” characteristic of many drugs of abuse, but stopping nicotine use often creates a withdrawal
syndrome that includes craving, irritability, anxiety, reduced heart rate, and reduced
activity in the brain’s reward pathways (Epping-Jordan et al., 1998; Hughes, Higgins, &
Bickel, 1994). Some smokers appear to develop only a psychological dependence on
nicotine (Robinson & Pritchard, 1995), but whether the dependence is physiological or