Face pareidolia is associated with right striatal dysfunction in drug-naive patients with Parkinson's disease

Background and aim Some patients with Parkinson's disease (PD) present with pareidolia, an illusion of a meaningless stimulus as a familiar object known to the observer. Since the striatum is associated with processing of visual information, we investigated correlations of pareidolia with motor symptoms and striatal dopaminergic function. Method A noise pareidolia test, assessment of motor symptoms using MDS-UPDRS and I-123-Ioflupane SPECT were performed in 58 drug-naive PD patients. A number of images in which a participant noticed an illusory face (number of illusory responses) were compared with motor assessment scores and uptake of I-123-ioflupane in the striatum. Results Of the 58 participants, 22 had at least one illusory response. Mean scores for MDS-UPDRS part III (p<0.05), rigidity (p<0.05), and rigidity on the left side of the body (p<0.01) in patients with pareidolia were significantly higher than those in patients without pareidolia. Uptake of I-123-ioflupane in the right caudate nucleus (p<0.05), anterior putamen (p<0.01), and posterior putamen (p<0.01) in patients with pareidolia was significantly lower than in patients without pareidolia. In the 22 patients with pareidolia, the number of illusory responses was significantly correlated with total scores for MDS-UPDRS part III (r=0.443, p<0.05) and subscores for bradykinesia (r=0.440, p<0.05) and bradykinesia on the left side of the body (r=0.564, p<0.01). The prevalence of pareidolia in left-dominant parkinsonism (16/30 patients) was higher than that in right-dominant parkinsonism (6/28 patients) (p<0.05 by chi-square test). Conclusion Pareidolia in PD patients is associated with dysfunction in the right striatum.

Automated summary

The study found that pareidolia in patients with Parkinson's disease may be associated with dysfunction in the right striatum and has correlations with motor symptoms.