Profile and progression of cognitive deficits in Progressive Supranuclear Palsy, Multiple System Atrophy and Parkinson's Disease

Objective: This study investigated neuropsychological tests most sensitive in differentiating progressive supranuclear palsy (PSP) from Parkinson’s disease (PD) and multiple system atrophy (MSA), and in detecting cognitive changes at follow-up. Background: Cognitive impairment is frequent in PSP, but its characteristics and progression need to be properly defined. Method: We evaluated 35 PSP with Richardson’s syndrome (PSP-RS), 30 MSA as well as 65 age-, sex-, and education-matched PD with an extensive clinical and neuropsychological assessment, allowing Level II cognitive diagnosis. Eighteen PSP, 12 MSA and 30 PD had a second evaluation 12-18-month (mean 15 months) after the first assessment. Results: In PSP, Montreal Cognitive Assessment (MoCA), verbal fluencies (phonemic and semantic tasks), Stroop test, Digit Span Sequencing (DSS), incomplete letters of Visual Object and Space Perception (VOSP) and Benton’s Judgment of Line Orientation (JLO) performance were significantly impaired at baseline compared to PD and MSA. Executive and visuo-spatial abilities declined longitudinally in PSP, but not in PD and MSA. After 1.5 year, 16% of PSP converted to dementia. Conclusion: Our study provides evidence that cognitive decline is more severe and rapid in PSP than PD and MSA. MoCA, verbal fluency, DSS and Benton’s JLO are valuable tests to detect cognitive progression in PSP and may be proposed as biomarker for research protocols to assess efficacy of disease modification strategies.