Delusions and Hallucinations

Psychotic symptoms (hallucinations and delusions) can occur in both clinical and normal, “non-clinical” populations.^[1] Thus, having a deep understanding of the phenomenology and possible diagnoses behind various subtypes of delusions and hallucinations is an important part of the diagnostic toolkit.

• Olfactory hallucinations (phantosmia) are hallucinations involving smells, and can occur in psychiatric disorders including schizophrenia spectrum disorders, temporal lobe seizures, brain neoplasms, and Parkinson's Disease.^[2][3]

• Auditory hallucinations are the most common type of hallucination in non-organic (i.e. - primary) psychiatric conditions
• When assessing auditory hallucinations, ask:
  • Does the patient hear one or several voices?
  • Are the voices male or female?
  • Are the voices or people they know or are they unfamiliar?
  • Are these voices simple statements, or complex sentences?
  • Do the voices engage in a conversation with the patient or comment on the patient’s thoughts?
• Command auditory hallucinations are frequently considered a concerning feature of psychosis that requires inpatient hospitalization. However, in regards to suicide risk, the presence of command hallucinations is not an independent predictor of suicide attempts.^[4] Only individuals who were previously predisposed to suicide attempts have a higher risk of completed suicide.^[5]
• Monosymptomatic auditory hallucinations, especially with recent substance use, can sometimes resolve without antipsychotic treatment.^[6]
• Individuals with hearing loss or impairment may experience non-specific auditory hallucinations that are non-psychiatric in etiology.
  • Individuals may report hearing sounds including sounds of familiar or unfamiliar voices, music, bells, animals, machines.
  • The use of hearing aids or reducing the hearing impairment may reduce the auditory hallucinations in these cases.^[7]
  • Individuals with hearing loss may also report a history of tinnitus; when inquiring about tinnitus, red flags that may warrant an otolaryngology (ENT) referral include:
    • Pulsatile tinnitus locked in time with the heartbeat
    • Unilateral tinnitus or unilateral hearing loss
    • Severe, disabling tinnitus

• Hypnagogic and hypnopompic hallucinations are non-psychotic disorder type hallucinations that can occur in sleep disorders and within normal populations. Hypnagogic hallucinations are vivid perceptual experiences occurring at sleep onset at night, while hypnopompic hallucinations are similar experiences that occur at awakening in the morning.

• Visual hallucinations can be both psychiatric or neurological and it is important to understand what exactly is occurring. Visual hallucinations should prompt a more detailed neurologic history and exam.
• Migraines are the most common single cause of visual hallucinations and illusions.
• Visual phenonemona (e.g. - auras from seizures) can also be reported as visual hallucinations.
• Individuals with Dementia with Lewy Bodies may experience visual hallucinations are part of their core symptoms.
• Charles Bonnet Syndrome (CBS) is a common non-psychiatric condition among people with serious vision loss (macular degeneration, glaucoma, and diabetic retinopathy) characterized by temporary visual hallucinations.
• Individuals with narcolepsy may also experience visual hallucinations

• Cenesthetic hallucinations are a type of somatic hallucination that involves involves visceral organs. For example, a patient with schizophrenia may report a pushing sensation in the blood vessels, feeling that their brain is on fire, or a cutting sensation in their bone marrow.^[8] Parkinson's patients on dopaminergic agents may also report these types of hallucinations.^[9]

• Delusions in the elderly can be different from those of younger patients.
• Delusions in the elderly are reality-based, unlike the fantastic delusions of early onset schizophrenia. Furthermore, delusions in the elderly do not share other characteristic symptoms of schizophrenia.^[10]
  • Thought withdrawal, thought insertion, and thought broadcasting are not typically seen in patients with late-onset schizophrenia

• Delusions of reference are delusions characterized by beliefs that random events are ascribed to particular importance for the self.

• Grandiose delusions are characterized by overestimation of one's abilities, most commonly seen in mania in bipolar disorder.

• Erotomanic delusions are characterized by the belief is another person is in love with the individual.

• Nihilistic delusions are characterized by a conviction that all is lost, and everything is hopeless. It can commonly be seen in psychotic depression in the elderly.

• Delusions of guilt are characterized by ungrounded feeling of remorse or extreme guilt of delusional intensity.

• Delusions of sin are characterized by fixed false beliefs that failed or defiled certain religious commandments.

• Somatic delusions are characterized by fixed false beliefs that one's bodily function or appearance is grossly abnormal (e.g. - “my organs are rotting inside”).

• Delusions of poverty/impoverishment are characterized by fixed false beliefs that one's financial savings are lost (despite evidence to the contrary).

• Delusions of theft are characterized by the beliefs that one's belongings have been stolen someone. This can be a prodrome for neurodegenerative disorders such as Alzheimer's dementia, when individuals have in fact misplaced their belongings.

• Hypochondriacal delusions are characterized by the delusional belief that one is afflicted with a medical disorder of defect.

• Delusions of persecution is characterized by the delusional belief that one is being targeted by an individual, group, or entity (conspired against, cheated, spied on, followed, poisoned or drugged, maliciously maligned, harassed, or obstructed). It is most commonly seen in primary psychotic disorders such as schizophrenia.

• Mood-congruent psychotic symptoms means that the content of the hallucinations and delusions is consistent with typical depressive themes.

• Mood-incongruent psychotic features means that the content of the hallucinations and delusions do not involve typical depressive themes.