D

delusion A false perception or belief that persists
even in confrontation with a reality that demon-
strates its falseness. There may be an element of
absurdity or bizarreness to the delusion or the
delusion may appear to have some plausibility
until closer examination refutes it. Many people
have delusions yet function normally in the
world. Delusions of persecution, being followed or
watched, or infidelity in a relationship can result
in behaviors that cause distress for the person and
for others. There is no particular treatment for
delusions. Delusions are also common compo-
nents of psychotic disorders such as SCHIZOPHRENIA,
in which case treatment attempts to manage
symptoms of the disorder overall.
See also COGNITIVE FUNCTION AND DYSFUNCTION;
HALLUCINATION; PARANOIA; PSYCHOSIS.

depression A psychologic condition of dimin-
ished emotional, cognitive, and physical function.
Everyone feels sad and out of sorts with the
events in their lives at some point. When these
feelings interfere with the activities of daily life,
they constitute clinical depression (also called
major depression), a health condition that
requires medical treatment. About 25 percent of
adults and 12 percent of teens in the United States
have depression, though fewer than half seek
treatment.

Suicide is a significant risk in untreated

depression. It is important to take seri-

ously statements people make about

taking their own lives or “ending it”

and to do what is possible to help them

get appropriate evaluation and care.

Symptoms and Diagnostic Path

The common symptoms of depression include

• feeling hopeless, worthless, helpless, or empty


• loss of interest in activities, work, friends, and
  family


• diminished LIBIDO(interest in sex), SEXUAL DYS-
  FUNCTION, or ERECTILE DYSFUNCTION


• difficulty concentrating and remembering


• sleep disturbances—sleeping all the time, being
  unable to sleep, or changes in the usual sleep
  pattern


• chronic HEADACHE, gastrointestinal distress, or
  body aches and discomforts that do not have
  apparent cause or respond to efforts to relieve
  them


• irritability, short temper, restlessness


• thoughts of death or ways to take one’s own
  life

The diagnostic path begins with a comprehen-

sive physical examination, NEUROLOGIC EXAMINA-

TION, and evaluation for substance abuse because

numerous common health conditions (such as

untreated HYPOTHYROIDISM or ANEMIA) and many

drugs can cause symptoms of depression. Further

evaluation includes psychologic assessment and an

attempt to determine whether the person may be

contemplating suicide.

Treatment Options and Outlook

About 80 percent of people who have depression

take ANTIDEPRESSANT MEDICATIONS, some as sole

treatment and others in combination with PSY-

CHOTHERAPY. The most commonly prescribed anti-

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