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Updated: Feb 9, 2026

Using Retinal Imaging to Study Dementia
Published on: November 6, 2017
Negative mood invites psychotic false perception in dementia.
Hiroyuki Watanabe1, Yoshiyuki Nishio1, Yasuyuki Mamiya1
1Department of Behavioral Neurology and Cognitive Neuroscience, Tohoku University Graduate School of Medicine, Sendai, Japan.
Negative mood significantly increases hallucinations in dementia with Lewy bodies (DLB) patients by heightening perceptual bias. This suggests abnormal perceptual priors in psychosis have an affective component, impacting cognition and perception.
Area of Science:
- Neuroscience
- Psychiatry
- Cognitive Psychology
Background:
- Predictive coding theories suggest psychosis involves abnormal perceptual priors.
- Psychological factors influencing these priors in hallucinating patients remain underexplored.
- The link between affective disorders and psychosis indicates a role for mood and emotion.
Purpose of the Study:
- To investigate the influence of mood on perceptual biases in patients with dementia with Lewy bodies (DLB) and Alzheimer's disease (AD).
- To explore the affective nature of abnormal perceptual priors in psychotic false perceptions.
Main Methods:
- Thirty-six DLB patients and 12 AD patients participated.
- Mood was experimentally induced (negative vs. neutral).
- Participants underwent a pareidolia test to measure hallucination-like illusions.
Main Results:
- DLB patients exhibited doubled pareidolic illusions in negative mood versus neutral mood.
- AD patients showed no significant mood-related difference in pareidolic responses.
- Signal detection analysis indicated affective modulation was due to perceptual bias, not sensory decline.
Conclusions:
- Abnormal perceptual priors in psychotic false perception possess an affective quality.
- These affective priors may represent a type of cognitive feeling linked to perception and cognition.
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