Objective: To evaluate free-water (FW) differences in patients with dementia with Lewy bodies (DLB) with versus without pareidolias

Background: Pareidolias are a type of illusion where individuals identify meaningful objects from ambiguous forms embedded in visual scenes. Pareidolias correlate with the presence of visual hallucinations and can distinguish individuals with DLB from Alzheimer disease. There is limited research on the neural basis of pareidolias in DLB, especially using diffusion-weighted MRI to assess tissue microstructure integrity in vivo.

Method: Baseline MRIs and Noise Pareidolia Task (NPT) scores from a 20-item NPT were obtained from 83 individuals with DLB. Imaging and clinical data were compiled from the Parkinson’s Disease Biomarkers Program (PDBP), 1Florida Alzheimer’s Disease Research Center (1FL ADRC) and National Alzheimer’s Coordinating Center (NACC). FW was analyzed in 63 regions of interest (ROIs) implicated in attention, visuospatial/visuoperceptual processes, and hallucinations. Majority of ROIs were from the Mayo Clinic Adult Lifespan Template and Atlases (MCALT). Primary outcome was FW difference between individuals with DLB, with versus without pareidolia errors (where >2 errors was classified as abnormal).

Results: We identified 21 DLB participants with >2 pareidolia errors and 62 with 0-2 errors. There were more women in the group with pareidolia errors (24% vs. 6%, p=0.027), but no significant differences in baseline age or education. After controlling for sex, participants with pareidolia errors had worse Movement Disorders Society Unified Parkinson’s Disease Rating Scale (MDS-UPDRS) part II subscore and total Montreal Cognitive Assessment (MoCA) score. Those with pareidolia errors were more likely to report presence of visual hallucinations on the Neuropsychiatric Inventory, but was not statistically significant. We found significant FW increase in the dorsal mesopontine area in DLB participants with pareidolia errors, after controlling for imaging site, age and sex (p=0.005).

Conclusion: Pareidolia in DLB may associate with microstructural changes in the dorsal mesopontine area. Dorsal mesopontine atrophy is typically seen in DLB, and FW increase in this region supports the hypothesized cholinergic dysfunction underlying pareidolia in DLB.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/free-water-mri-correlates-of-pareidolia-in-dementia-with-lewy-bodies/