Minor Hallucinations in Alzheimer's Disease

Area of Science:

• Neurology
• Psychiatry
• Cognitive Science

Background:

• Minor hallucinations (MHs), encompassing passage hallucinations, visual illusions, and presence hallucinations, represent a spectrum of hallucinatory experiences.
• Understanding MHs is crucial as they may manifest in neurodegenerative conditions.

Purpose of the Study:

• To investigate the prevalence and characteristics of MHs in patients with Alzheimer's disease (AD) and amnestic mild cognitive impairment (aMCI).
• To explore the relationship between MHs and cognitive function, behavioral symptoms, and psychoactive drug use in these patient groups.

Main Methods:

• Prospective recruitment of 268 subjects: 90 drug-naïve AD patients, 78 aMCI patients, and 100 controls.
• Utilized a semi-structured questionnaire to assess psychotic phenomena and collected clinical, neuropsychological, and demographic data.
• Compared data between patients with and without MHs, matched for age, sex, and education.

Main Results:

• MH prevalence was significantly higher in AD (21.1%) and aMCI (12.8%) compared to controls (3%).
• Presence hallucinations were the most frequent MH type, followed by passage hallucinations and illusions.
• MHs showed a negative correlation with Mini-Mental State Examination (MMSE) scores and a positive correlation with the Neuropsychiatric Inventory (NPI) scores, indicating poorer cognition and more behavioral symptoms.

Conclusions:

• MHs are more prevalent in newly diagnosed, untreated AD and aMCI patients than in controls.
• The presence of MHs is associated with diminished cognitive performance and increased behavioral disturbances.
• Routine screening for MHs is recommended as a clinical indicator in AD and aMCI populations.