Neuropsychological correlates of Pisa syndrome in patients with Parkinson's disease

Background: A complex relationship exists between postural control and cognition in the elderly. Namely, neural mechanisms that are required for the regulation of posture have been variably associated with cognitive dysfunctions. Parkinson's disease (PD) is the second most common neurodegenerative disease among the elderly, and it has been associated with both cognitive and postural abnormalities such as Pisa syndrome (PS). Although its onset has been considered to be multifactorial, the pathophysiological mechanisms underpinning PS are still not fully explained. Until now, no study investigated the possible contribution of cognitive dysfunction to occurrence of PS in PD. Patients and methods: Twenty PD patients with PS and 20 PD patients without PS were enrolled. All patients with PD underwent neuropsychological battery to assess behavioural disturbances, memory, attention, frontal/executive and visuospatial functions. Results: The two groups did not differ on demographic features, age at PD onset and disease duration, whereas they significantly differed on UPDRS-Part III, and levodopa-equivalent daily dose (LEDD). MANCOVA with above-mentioned clinical variable as covariates revealed significant differences on tasks tapping verbal long-term memory, and attentional and visuoperceptual abilities between groups. The binary logistic regression revealed that higher LEDD and lower performance on visuospatial task (Benton Judgment of Lines Orientation test) significantly predicted occurrence of PS. Conclusion: Our results revealed a significant association of PS with altered attention and visuoperceptual functions in PD, suggesting that the occurrence of PS may be associated with alteration of both frontal–striatal systems and posterior cortical areas.