Neuropathological analysis of cognitive impairment in progressive supranuclear palsy

Cognitive impairment is an important symptom in progressive supranuclear palsy (PSP), but the pathological changes underlying the cognitive impairment are unclear. This study aimed to elucidate relationships between the severity of cognitive impairment and PSP-related pathology.

We investigated the clinicopathological characteristics of 10 autopsy cases of PSP, including neuronal loss/gliosis and the burden of PSP-related tau pathology by using a semiquantitative score in 17 brain regions. Other concurrent pathologies such as Braak neurofibrillary tangle stage, Thal amyloid phase, Lewy-related pathology, argyrophilic grains, and TDP-43-related pathology were also assessed. We retrospectively divided the patients into a normal cognition group (PSP-NC) and cognitive impairment group (PSP-CI) based on antemortem clinical information about cognitive impairment and compared the pathological changes between these groups.

Seven patients were categorized into the PSP-CI group (men = 4) and three into the PSP-NC group (men = 3). The severity of neuronal loss/gliosis and concurrent pathologies were not different between the two groups. However, the total load of tau pretangles/neurofibrillary tangles was higher in the PSP-CI group than in the PSP-NC group. In addition, the burden of tufted astrocytes in the subthalamic nucleus and medial thalamus was higher in the PSP-CI group than in the PSP-NC group.

Cognitive impairment in PSP may be associated with the amount of tufted astrocyte pathology in the subthalamic nucleus and medial thalamus.