Abstract
Progressive supranuclear palsy (PSP) and frontotemporal lobar degeneration (FTD) are two clinicohistological entities that share a severe prefrontal syndrome. To what extent do the cognitive syndrome and the location of the underlying brain atrophy unify or segregate these entities? Here, we examined the clinical and radiological patterns of frontal involvement and the neural bases of the cognitive dysfunctions observed in the Richardson form of PSP and the behavioral variant of FTD (bvFTD). The cognitive profile and grey and white matter volume of PSP (n = 19) and bvFTD (n = 16) patients and control participants (n = 18) were compared using a standard battery of neuropsychological tests and voxel-based morphometry (VBM), respectively. Analyses of correlations between neuropsychological and morphometric data were additionally performed. The severity and qualitative pattern of cognitive dysfunction was globally similar between the two patient groups. Grey matter volume was decreased in widespread frontal areas and in the temporal uncus in bvFTD, while it was decreased in the frontal and temporal lobes as well as in the thalamus in PSP. We also found an unexpected involvement of the frontal rectal gyrus in PSP patients compared to controls. Correlation analyses yielded different results in the two groups, with no area showing significant correlations in PSP patients, while several frontal and some temporal areas did so in bvFTD patients. In spite of minor neuropsychological and morphological differences, this study shows that the patterns of cognitive dysfunction and atrophy are very similar in PSP and bvFTD. However, executive dysfunction in these diseases may stem from partially divergent cortical and subcortical neural circuits.
Highlights
Progressive supranuclear palsy (PSP) and frontotemporal lobar degeneration (FTD) are usually considered two distinct clinicohistological entities
The topography of neurodegeneration is mostly cortical in FTD, affecting the ventromedial prefrontal cortex (PFC) and to some extent the temporal lobes and dorsal PFC [1], while it is mostly subcortical in PSP, affecting the brainstem, cerebellum and basal ganglia [2]
Behavioral data There was no significant difference between the three groups regarding age at examination, sex or education, nor was there any difference in disease duration or Mini-Mental State Examination (MMSE) score between behavioral variant of FTD (bvFTD) and PSP patients
Summary
Progressive supranuclear palsy (PSP) and frontotemporal lobar degeneration (FTD) are usually considered two distinct clinicohistological entities. From a clinical standpoint, it is important to note that PSP and FTD share a prominent frontal cognitive syndrome, which is consistently seen in the ‘‘classic’’ Richardson form of PSP It is present in more than half the patients from the first year of the clinical disease [4], and consists mostly of a dysexecutive syndrome with ‘‘cognitive inertia’’, i.e. an increased latency of responses, the impairment of information retrieval and reasoning and a lack of mental flexibility [5,6]. It is sometimes difficult, at least in the early stages, to clinically distinguish these atypical forms of PSP from the behavioral variant of FTD (bvFTD) [18]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
