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  • Updated 08.16.2022
  • Released 08.07.1997
  • Expires For CME 08.16.2025

Progressive supranuclear palsy: cognitive and behavioral changes

Introduction

Overview

Many patients with progressive supranuclear palsy present to neurologists with unsteady gait, postural instability, and falls, but others come with complaints of cognitive slowing, apathy, loss of verbal fluency, and loss of ability to recognize emotion in others. There are now at least seven well-defined syndromes that are subtypes of progressive supranuclear palsy. The brains of patients with classic supranuclear palsy, or “Richardson syndrome” show frontal atrophy and excessive amounts of abnormally aggregated tau protein. The apathy of supranuclear palsy is associated with atrophy of the ventromedial frontal cortex. The cognitive slowing is correlated with fronto-cerebellar gray matter atrophy and widespread changes in white matter tracts. Patients with the clinical variant of “PSP-parkinsonism” present with dysarthria, asymmetrical tremors, rigidity, and slowness that respond for one or two years to levodopa (they do not have early gaze palsy and their brains show less severe tau pathology and less severe cortical atrophy). In this update, the authors describe how the cognitive and behavioral changes in patients with progressive supranuclear palsy can be used to distinguish it from other common neurodegenerative syndromes, such as Parkinson disease, dementia with Lewy bodies, Alzheimer disease, frontotemporal dementia, multiple system atrophy, and corticobasal degeneration. New data about the use of various neuroimaging tools in the diagnosis of supranuclear palsy are described.

Key points

• Patients with progressive supranuclear palsy are more likely to progress faster if they have poorer baseline performance on cognitive tests. This is particularly true of the PSP-Richardson syndrome variant and the PSP-behavioral variant, where mean survival is about 7 years, compared to 11 years for the milder “brainstem predominant” variants of supranuclear palsy (PSP-parkinsonism and PSP-pure akinesia with gait freezing).

• The most common cognitive impairment in PSP-Richardson syndrome is the frontal dysexecutive syndrome, which is manifested by difficulty with planning and organization. These patients also have problems with apathy, rigid thinking, and lack of emotional recognition in others (alexithymia). Midbrain atrophy is in the common imaging feature of PSP-Richardson syndrome and all other progressive supranuclear palsy variants.

• Apathy is the most common behavioral symptom seen in several of the main subtypes of supranuclear palsy. Apathy has significant negative predictive value for health-related quality of life and appears to be correlated with dysfunction of prefrontal subcortical white matter tracts. Survival is worse in PSP patients who have high apathy scores, compared to patients with frontotemporal dementia or primary progressive aphasia, who have lower apathy scores.

• Alexithymia, the inability to recognize emotions in others, is identifiable within the first 2 years of both PSP-Richardson syndrome and PSP-parkinsonism patients. The symptom of alexithymia can differentiate early progressive supranuclear palsy patients from those who are in the early stages of Parkinson disease. Alexithymia in progressive supranuclear palsy patients can be predicted by the presence of depression.

Historical note and terminology

In 1877, Dr. Charcot described a 40-year-old woman who had rigid-akinetic parkinsonism, neck dystonia, dysarthria, and eye-movement problems (31). Chavany and others reported the clinical and pathologic features of a 50-year-old man with a rigid and akinetic form of parkinsonism with postural instability, neck dystonia, dysarthria, and staring gaze (32). Richardson, Steele, and Olszewski recognized the same clinical syndrome in eight patients and described the autopsy findings in six of them (143; 168). Vertical gaze palsy was noted to be a pathognomonic feature of this syndrome. Progressive supranuclear palsy was not a “new” disease in 1963, as 22 well-documented case reports had been identified in the neurologic literature between 1877 and 1963 (27). The unique frontal lobe cognitive changes of progressive supranuclear palsy (apathy, loss of spontaneity, slowing of thought processes, and loss of executive functions) were first described by Albert and colleagues (03). Now, progressive supranuclear palsy is included among several of the frontotemporal dementia syndromes, which are characterized by changes in behavior, executive dysfunction, or language problems (22). These syndromes involve abnormal tau pathology and frontotemporal network dysfunction. Besides progressive supranuclear palsy, these syndromes include corticobasal degeneration, primary progressive aphasia, and the behavioral variant of frontotemporal dementia.

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