Psychopharmacology

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Psychoactive Drugs
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dopamine, the same neurotransmitter that is involved in the experience of reward or
pleasure (Kjaer et al., 2002).
Some people claim that meditation increases their awareness and understanding of
themselves and their environment. It has also been associated with reduced anxiety;
improved immune system functioning; reductions in high blood pressure anxiety and
insomnia; longer survival among heart patients; and improved performance in everything from work to tennis (Beauchamp-Turner & Levinson, 1992; Bodian, 1999; Davidson et al., 2003; Paul-Labrador et al., 2006; Schneider et al., 2005). More generally, meditators’ scores on personality tests indicate increases in overall mental health, self-esteem,
and social openness (Janowiak & Hackman, 1994; Sakairi, 1992). Exactly how meditation produces these benefits is unclear, though its activation of dopamine brain systems
may tell an important part of the story. Whatever the mechanism, it is probably not
unique to meditation. Many of the same benefits associated with meditation have also
been reported in association with other techniques, such as biofeedback, hypnosis, tai
chi, or just relaxing (Bernstein et al., 2000; Beyerstein, 1999; Wang, Collet, & Lau, 2004).
Psychoactive Drugs
䉴 How do drugs affect the brain?
Bernadine Coady, of Wimblington, England, has
a condition that makes general anesthesia
dangerous for her. In April 1999, she faced
a foot operation that would have been
extremely painful without anesthesia. She
arranged for a hypnotherapist to help her
through the procedure, but when he
failed to show up, she was forced to rely
on self-hypnosis as her only anesthetic.
She said she imagined the pain as “waves
lashing against a sea wall . . . [and] going
away, like the tide.” Coady’s report that
the operation was painless is believable
because, in December 2000, she had the
same operation on her other foot, again
using only self-hypnosis for pain control
(Morris, 2000).
SURGERY UNDER HYPNOSIS
psychoactive drugs Chemical substances that act on the brain to create
psychological effects.
psychopharmacology The study of
psychoactive drugs and their effects.
blood-brain barrier A feature of blood
vessels in the brain that prevents some
substances from entering brain tissue.
agonists Drugs that bind to a receptor
and mimic the effects of the neurotransmitter that normally fits that receptor.
antagonists Drugs that bind to a receptor and prevent the normal neurotransmitter from binding.
The altered states we have discussed so far serve a biological need (sleep) or rely on the
chemistry of the brain and body (hypnosis and meditation). Other altered states are
brought on by outside agents: drugs. Every day, most people in the world use drugs
that alter brain activity and consciousness (Levinthal, 2001). For example, 80 to 90 percent of people in North America use caffeine, the stimulant found in coffee and tea. A
drug is a chemical that is not required for normal physiological functioning yet has an
effect on the body. You may say that you “need” a cup of coffee in the morning, but
you will still wake up without it; accordingly, the caffeine in coffee is defined as a drug.
Drugs that affect the brain, changing consciousness and other psychological processes,
are called psychoactive drugs. The study of psychoactive drugs is called psychopharmacology.
Psychopharmacology
Most psychoactive drugs affect the brain by altering the interactions between neurotransmitters and their receptors, as described in the chapter on biology and behavior.
To create their effects, these drugs must cross the blood-brain barrier, a feature of
blood vessels in the brain that prevents some substances from entering brain tissue
(Neuwelt, 2004). Once past this barrier, a psychoactive drug’s effects depend on several
factors: With which neurotransmitter systems does the drug interact? How does the
drug affect those neurotransmitters or their receptors? What psychological functions
are normally performed by the brain systems that use those neurotransmitters?
Drugs can affect neurotransmitters or their receptors through several mechanisms.
Neurotransmitters fit into their own receptors, as Figure 4.8 shows. Some drugs, such
as morphine, are similar enough to a particular neurotransmitter to fool its receptors.
These drugs, called agonists, bind to receptors and imitate, or mimic, the effects of
the normal neurotransmitter. Other drugs, called antagonists, are similar enough to
a neurotransmitter to occupy its receptors but cannot mimic its effects. When they bind
to receptors, they prevent the normal neurotransmitter from binding. Still other drugs
work by increasing or decreasing the release of a specific neurotransmitter. Finally, some
drugs work by speeding or slowing the removal of a neurotransmitter from synapses.
Predicting a psychoactive drug’s effects on behavior is complicated. For one thing,
most of these drugs interact with many neurotransmitter systems. Also, the nervous
system may compensate for a given drug’s effects. For instance, repeated exposure to a