114 Schizophrenia Spectrum and Other Psychotic Disorders
Development and Course
The initiation of the disorder may vary co nsiderably with the substance. For example,
smoking a high dose of cocaine may produce psychosis within minutes, whereas days or
weeks of high-dose alcohol or sedative use ma y be required to produce psychosis. Alco-
hol-induced psychotic disorder, with hallucina tions, usually occurs only after prolonged,
heavy ingestion of alcohol in individuals who have moderate to severe alcohol use disorder,
and the hallucinations are generally auditory in nature.
Psychotic disorders induced by amphetamine and cocaine share similar clinical fea-
tures. Persecutory delusions may rapidly develop shortly af ter use of amphetamine or a
similarly acting sympathomimetic. The hallucination of bugs or vermin crawling in or un-
der the skin (formication) can lead to scratchi ng and extensive skin excoriations. Cannabis-
induced psychotic disorder may develop shortl y after high-dose cannabis use and usually
involves persecutory delusions, marked anxiety, emotional lability, and depersonalization.
The disorder usually remits within a day bu t in some cases may persist for a few days.
Substance/medication-induced psychotic disord er may at times persist when the offend-
ing agent is removed, such that it may be difficult initially to distinguish it from an indepen-
dent psychotic disorder. Agents such as amph etamines, phencyclidine, and cocaine have been
reported to evoke temporary ps ychotic states that can someti mes persist for weeks or longer
despite removal of the agent and treatment with  neuroleptic medication. In later life, poly-
pharmacy for medical conditions and exposure to medications for parkinsonism, cardiovas-
cular disease, and other medi cal disorders may be associated  with a greater likelihood of