Page 603 - First Aid for the USMLE Step 1 2020, Thirtieth edition [MedicalBooksVN.com]_Neat

Psychiatry ` Psychiatry—Pathology Psychiatry ` Psychiatry—Pathology sEctiON iii 559

Psychosis Distorted perception of reality characterized by delusions, hallucinations, and/or disorganized
thought/speech. Can occur in patients with medical illness, psychiatric illness, or both.
Delusions False, fixed, idiosyncratic beliefs that persist despite evidence to the contrary and are not typical
of a patient’s culture or religion (eg, a patient who believes that others are reading his thoughts).
Types include erotomanic, grandiose, jealous, persecutory, somatic, mixed, and unspecified.
Disorganized thought Speech may be incoherent (“word salad”), tangential, or derailed (“loose associations”).
Hallucinations Perceptions in the absence of external stimuli (eg, seeing a light that is not actually present).
Contrast with misperceptions (eg, illusions) of real external stimuli. Types include:
ƒ Auditory—more commonly due to psychiatric illness (eg, schizophrenia) than medical illness.
ƒ Visual—more commonly due to medical illness (eg, drug intoxication, delirium) than
psychiatric illness.
ƒ Tactile—common in alcohol withdrawal and stimulant use (eg, “cocaine crawlies,” a type of
delusional parasitosis).
ƒ Olfactory—often occur as an aura of temporal lobe epilepsy (eg, burning rubber) and in brain
tumors.
ƒ Gustatory—rare, but seen in epilepsy.
ƒ Hypnagogic—occurs while going to sleep. Sometimes seen in narcolepsy.
ƒ Hypnopompic—occurs while waking from sleep (“get pomped up in the morning”).
Sometimes seen in narcolepsy.

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