Delusions, Hallucinations, Illusions, and Loose Associations

Overview

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  • Delusions
    • false beliefs firmly maintained in spite of indisputable and obvious proof to the contrary
      • not shared with other members of patient’s culture/subculture
    • e.g. thinking the CIA is spying on you
  • Hallucinations
    • perceptions in the absence of external stimuli
    • e.g. hearing sound when no sound is present
  • Illusions
    • misinterpretations of actual external stimuli
    • e.g. hearing the wind blowing and thinking it is a bird chirping
  • Loose associations
  • ideas are presented with illogical or tenuous connections between them

Hallucination types

  • Visual hallucinations
    • common in delirium
    • more often a feature of medical rather than psychiatric illness
  • Auditory hallucinations
    • common in schizophrenia
    • more common in psychiatric than medical disease
  • Olfactory hallucinations
    • often occurs as an aura of psychomotor epilepsy or brain tumors
  • Gustatory hallucination
    • rare
  • Tactile hallucinations
    • common in alcohol withdrawal
      • e.g. formication – the sensation of ants crawling on one’s skin
    • also seen in cocaine abusers (“cocaine bugs”) 
  • Hypnagogic hallucination
    • occurs while going to sleep
  • Hypnopompic hallucination
    • occurs while waking from sleep