Pareidolic Illusions and Associated Lower Regional Gray Matter Volumes in Community-Dwelling Older Adults Without Dementia: The Arakawa 65+ Study.

OBJECTIVES

Pareidolic illusions involve perceiving meaningful objects in ambiguous or visually complex stimuli. Although seen in dementia, their presence and associated neuroanatomical basis in older adults without dementia remain unclear. Investigating these illusions in this population may reveal early neurodegenerative changes preceding overt dementia. Such insights could support the use of pareidolic illusions as potential early markers for diagnosis and intervention. This study therefore aimed to examine the prevalence and associated neuroanatomical characteristics of pareidolic illusions in community-dwelling older adults without dementia, as assessed by the Noise Pareidolia Test (NPT).

METHODS

We investigated the prevalence of pareidolic illusions in older adults aged 65-84 residing in Tokyo, Japan with suspected cognitive decline but without dementia. Participants were classified as cognitively normal or having mild cognitive impairment (MCI) based on standard criteria. Participants underwent NPT, and those who exhibited one or more pareidolic illusions were classified as pareidolia-positive. Additionally, a whole-brain voxel-based morphometry (VBM) of structural magnetic resonance imaging data was performed to assess gray matter volume differences associated with pareidolic illusions.

RESULTS

Pareidolic illusions were present in 35.1% (155/441) of participants. These individuals were significantly older, had shorter years of education, and more likely to be diagnosed with MCI. VBM revealed significantly lower gray matter volume in bilateral temporal clusters-areas associated with face-related visuoperceptual processing-among pareidolia-positive individuals.

CONCLUSIONS

Pareidolic illusions were relatively common in community-dwelling older adults without dementia. These illusions may be an early marker of neurodegenerative changes affecting visuoperceptual pathways, and may be detectable using NPT.