DEPRESSANTS
Depressants are broadly defined as drugs that decrease activity in the
nervous system.Many depressants are available to us; one is alcohol, a widely
used recreational drug in many countries, but also widely used by people as a way
of managing their own stress and anxiety. Other depressants are commonly
prescribed by physicians; these drugs include medications (e.g., zolpidem)
given to people who have trouble sleeping, and drugs (usually benzodiazepines,
such as Valium or Xanax) used to treat anxiety.
Depressants are helpful in many
circumstances—but if they’re misused or overused, they can lead to serious
medical and psychological difficulties. For example, both the benefits and the
problems associated with alcohol are well documented. At low doses, alcohol
produces feelings of pleasure and well-being. But alcohol also depresses
activ-ity in neural circuits that ordinarily control our impulses, and when
these (inhibitory) circuits are less active, people are likely to engage in a
wide range of behaviors they would ordinarily avoid. If provoked, they’re more
likely to be aggressive. If tempted toward sexual behavior, they’re more likely
to give in to the temptation. But the same mechanisms can also promote positive
behaviors. For example, people asked for charitable donations are more likely
to say yes if they’ve had a drink or two; restaurant customers are more likely
to leave generous tips after they’ve enjoyed a bottle of wine.
This relaxation of inhibition
can, of course, create enormous dangers. Thus, people who understand perfectly
well the dangers of driving an automobile while drunk may still get behind the
wheel of a car—thanks, in large part, to impairment in brain circuits that
would ordinarily forbid such behavior. Then, once the person is behind the
wheel, alcohol’s other effects come into play—slower reaction times, poor
coordination, and impaired decision making. All of this makes it easy to
understand why, according to annual surveys by the National Highway Traffic Safety
Administration, almost half of the deaths from traffic accidents in the United
States involve alcohol consumption. Similar data have been reported in many
other countries.
Researchers have further
suggested that alcohol produces a narrowing of attention, so that people who
have been drinking pay attention to a diminished set of cues in the
envi-ronment and a smaller set of considerations from memory (Steele &
Josephs, 1990). As a result, the drinker’s thinking is very much tied to the
here and now, and he pays little atten-tion to the possible consequences of his
actions. This helps us understand why, for exam-ple, college students are less
likely to use condoms if they’ve been drinking—apparently, in this setting,
students pay less attention to the obvious dangers associated with unprotected
sex (MacDonald, Zanna, & Fong, 1996; MacDonald, Cohen, Stenger, &
Carter, 2000). This shortsighted thinking may also help explain why, according
to one estimate, alcohol is involved in 90% of the rapes and a similar proportion
of the violent crimes occurring on college campuses (Wechsler, Davenport,
Dowdall, Moeykens, & Castillon, 1994).
We should add, though, that
alcohol’s effects derive from a mix of the drug’s actual impact on brain
chemistry and people’s expectations
about its effects. In one study, half of the partic-ipants consumed an
alcoholic drink and half consumed an alcohol-free drink (Abrams & Wilson,
1983; also see Goldman, Brown, & Christiansen, 1987). In each group, half
of the participants thought they had consumed alcohol and half believed there
was no alcohol in the drink. (The taste of the drink, for all participants,
made it impossible for them to detect the alcohol, and so their beliefs about
the drink depended entirely on what the experimenter told them.) All
participants were then shown an erotic movie, and those who thought they had
consumed alcohol (whether they actually had or not) reported stronger sexual
fantasies in response to the film and reported feeling less guilt about these
fantasies. Alcohol, it seems, can release someone’s impulses through
psychological means as well as pharmaceutical ones.
What about the other depressants—sleeping pills or the various antianxiety drugs? These are highly effective if used appropriately, but they can also produce physical and psy-chological dependence, making withdrawal symptoms after prolonged use quite likely; the symptoms can include enhanced anxiety (a “rebound” effect), insomnia, or even seizures. In addition, people who’ve been taking these drugs for a long time often become less sen-sitive to the medication—a pattern known as drug tolerance—and so need a higher and higher dose to achieve the same effects. Unfortunately, at higher doses these drugs have further effects: High doses of benzodiazepines, for example, can cause cognitive impair-ment and, especially if combined with alcohol, can push the person into a coma.
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