delusion

delusion false belief based upon a misinterpretation of reality. It is not, like a hallucination, a false sensory perception, or like an illusion, a distorted perception. Delusions vary in intensity, and are not uncommon among substance abusers, particularly those who use amphetamines, cocaine, and hallucinogens. They also occur frequently among individuals who have been diagnosed with Alzheimer's disease , Huntington's disease , or schizophrenia , and during the manic stage of bipolar disorder (see depression ). Some common delusions include persecutory delusions, in which the individual falsely believes that others are plotting against him; delusions of thought broadcasting, where the individual believes his thoughts can be transmitted to others; delusions of thought insertion, in which the individual believes that thoughts are being implanted in his mind; and delusions of grandeur, in which the individual imagines himself an unappreciated person of great importance.

delusion (di-loo-zhŏn) n. a belief that is held with unshakable conviction, cannot be altered by rational argument, and is outside the person's normal belief system. It may be a symptom of mania, schizophrenia, or an organic psychosis. See also paranoia.

delusion False or irrational belief based upon a misinterpretation of reality. Mild delusions are quite common, but fixed delusions can be a symptom of paranoia.