Delusions vs. Hallucinations vs. Paranoia: Understanding the Differences

These are distinct psychotic phenomena, though they can co-occur.

Definitions

• Delusion: Fixed false belief resistant to reason/evidence. Types: persecutory, referential, grandiose, erotomanic, nihilistic, somatic.
• Hallucination: Perception without external stimulus. Auditory (most common), visual, tactile, olfactory, gustatory.
• Paranoia: Intense suspiciousness/mistrust; belief others intend harm. Can be a delusional theme (persecutory delusion) or a personality trait (paranoid personality disorder).

Key Distinctions

Feature	Delusion	Hallucination	Paranoia
Nature	Belief (cognitive)	Perception (sensory)	Attitude/affect (suspicion)
Reality testing	Absent	Absent (for the percept)	May be intact (non-delusional)
Content	Varied themes	Sensory modality	Mistrust, hypervigilance

Clinical Contexts

• Schizophrenia: both delusions & hallucinations.
• Delusional disorder: delusions only (≥1 month, no other psychosis).
• Mood disorders with psychotic features.
• Substance-induced (stimulants, steroids, withdrawal).
• Medical: delirium, dementia, brain lesions.

Assessment

Clinician evaluates conviction, bizarreness, impact on function, and insight. Collateral history crucial.