Prospective Characterization of Cognitive Function in Typical and ‘Brainstem Predominant’Progressive Supranuclear Palsy Phenotypes

OBJECTIVE: Clinicopathological studies over the last decade have broadened the clinical spectrum of progressive supranuclear palsy (PSP) to include several distinct clinical syndromes. We examined the cognitive profiles of patients with PSP-Richardson’s syndrome (PSP-RS) and two atypical ‘brainstem predominant’ PSP phenotypes (PSP-parkinsonism, PSP-P; and PSP-pure akinesia with gait freezing, PSP-PAGF) using a comprehensive neuropsychological battery. METHODS: Fourteen patients diagnosed as PSP-RS, three patients with PSP-P and four patients with PSP-PAGF were assessed using a comprehensive battery of neuropsychological tests. RESULTS: The typical PSP-RS subgroup demonstrated greater impairments in processing speed [t(19) = -4.10, p = 0.001 (d =1.66)] and executive function [t(19) = -2.63, p = 0.02 (d = 1.20)] compared to the ‘brainstem predominant’ PSP phenotype. CONCLUSION: This is the first prospective study to demonstrate that PSP-RS and ‘brainstem predominant’ PSP phenotypes can be differentiated on cognitive grounds. These differences correspond with variations in pathological profiles reported in the literature.