Minor Hallucinations Distinguish Early DLB From AD

TOPLINEAmong patients in the early stages of Alzheimer’s disease (AD) or dementia with Lewy bodies (DLB), minor hallucinations and pareidolic responses were the most discriminating features of DLB, whereas episodic memory impairment was the most distinctive marker of AD, a new study has found.METHODOLOGYFor this prospective, observational, cross-sectional study, conducted at a specialized dementia unit in Spain, researchers compared patients with probable AD (n = 60) to those with probable DLB (n = 61), all in mild stages of cognitive impairment (Global Deterioration Scale stage 3-4).AD diagnosis was confirmed using amyloid PET or cerebrospinal fluid biomarkers according to the 2018 National Institute on Aging-Alzheimer’s Association criteria. DLB diagnosis was confirmed using the 2017/2020 consensus criteria of the DLB Consortium, requiring at least one positive indicative biomarker (abnormal dopamine transporter imaging, reduced cardiac uptake on metaiodobenzylguanidine scintigraphy, or a polysomnographic confirmation of rapid eye movement [REM] sleep behavior disorder).Participants underwent a standardized clinical assessment; comprehensive neuropsychological evaluation, including the Mini-Mental State Examination, Free and Cued Selective Reminding Test, and Visual Object and Space Perception Battery, and other tests; and structured evaluation of psychotic symptoms.Perceptual testing included the pareidolia test to assess susceptibility to illusory visual perceptions, with researchers recording the number of pareidolic responses, omissions, and total errors. Parkinsonian motor signs were assessed using a five-item version of the Unified Parkinson’s Disease Rating Scale.TAKEAWAYPatients with DLB showed a significantly higher prevalence of minor hallucinations than those with AD (54.1% vs 13.3%; P < .001), with presence and passage hallucinations being substantially more prevalent in patients with DLB. The presence of minor hallucinations had a positive predictive value of 0.8 for DLB. Global cognition, executive functions, attention, language measures, and visuospatial abilities were comparable between groups.The number of pareidolic responses was significantly higher in the DLB group than in the AD group (median, 2 vs 0; P = .008), and this measure showed the highest discriminative accuracy among perceptual measures for distinguishing DLB from AD.The core clinical features of DLB such as REM sleep behavior disorder, cognitive fluctuations, and visual hallucinations were significantly more frequent in the DLB group than in the AD group (55% vs 10%; 29.5% vs 3.3%; and 27.9% vs 1.7%, respectively; P < .001 for all). The total score for parkinsonian motor burden was significantly higher in the DLB group than in the AD group (P < .001).Patients with AD scored significantly worse across all recall measures on the Free and Cued Selective Reminding Test, including total free recall, total recall, delayed free recall, and delayed total recall, as well as on the T&M test (P < .001 for all).IN PRACTICE“In early disease stages, MH [minor hallucination] and susceptibility to perceptual distortions differentiate DLB from AD more effectively than standard cognitive testing. Systematic assessment of these phenomena may improve early diagnostic accuracy in routine clinical practice,” the investigators wrote.SOURCEThe study was led by Marina Ruiz Piñero, Hospital San Vicente del Raspeig, Sant Vicent del Raspeig, Spain. It was published online on July 29 in the Journal of Alzheimer’s Disease.LIMITATIONSNeuropathologic confirmation of diseases was unavailable. The single-center design might have limited the generalizability of the findings. The cross-sectional design of the study prevented the longitudinal evaluation of hallucination evolution over time. Hallucinations might have been underreported or variably captured depending on patient insight and caregiver input. Lastly, concomitant co-pathology could not be fully excluded.DISCLOSURESThe study received no financial support. The investigators reported having no relevant conflicts of interest.This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.