Minor hallucinations as an early marker to differentiate dementia with Lewy bodies from Alzheimer's disease

Background Early differentiation between Alzheimer's disease (AD) and dementia with Lewy bodies (DLB) remains clinically challenging, particularly in the initial stages, when cognitive profiles largely overlap. Accurate diagnosis is increasingly relevant given disease-specific therapeutic implications. Objective To compare clinical, neuropsychological, and perceptual features of early-stage AD and DLB, with a particular focus on minor hallucinations (MH), and to assess their diagnostic utility in differentiating both conditions. Methods This prospective, cross-sectional study included 121 patients with probable AD (n = 60) or DLB (n = 61), all in mild stages (GDS 3–4) and supported by disease-specific biomarkers. Participants underwent standardized clinical assessment, comprehensive neuropsychological evaluation, structured evaluation of psychotic symptoms, and perceptual testing, including the Pareidolia Test. Group comparisons and ROC analyses were performed to assess discriminative accuracy. Results Global cognition, attention, executive functions, language, and visuospatial abilities largely overlapped between groups. Episodic memory impairment was significantly more severe in AD across all recall measures. In contrast, DLB patients showed a higher prevalence of core clinical features and a markedly higher frequency of MH (54.1% versus 13.3% in AD). Pareidolic responses were significantly more frequent in DLB and showed the highest discriminative accuracy among perceptual measures. The presence of MH demonstrated a high positive predictive value for DLB. Conclusions In early disease stages, MH 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.