Behavior and cognition in corticobasal degeneration and progressive supranuclear palsy.

Progressive supranuclear palsy (PSP) and corticobasal degeneration (CBD), previously described as Parkinsonian syndromes are also cognitive disorders, and biologically related to the frontotemporal dementia or Pick's disease. PSP and CBD overlap clinically, pathologically and genetically, sharing tau haplotypes and mutations. In our series of CBD/PSP patients with cognitive presentation (n=36), primary progressive aphasia (PPA) was particularly common, but behavioral onset occurred also. CBD or PSP as motor presentations developed significant language disorder in 17/19. The underlying pathology is predictably tau positive in these clinical combinations, regardless of the presentation. Other cognitive features of CBDS include apraxia, alien hand and apathy, but often frontal lobe dementia with disinhibition develops also. CBDS also has visuospatial deficit, because of the parietal involvement. PSP was considered the prototype of subcortical dementia, with bradyphrenia, poor recall and executive deficit, but cortical features were recognized to be important also. Language testing and a behavioral inventory should be part of neuropsychological tests to facilitate diagnosis and to quantify the deficit. The clinical, genetic and pathological relationship is strong between CBD /PSP and the aphasic and behavioral components of the Pick complex.