Progressive supranuclear palsy, multiple system atrophy and corticobasal degeneration.

Progressive supranuclear palsy (PSP), multiple system atrophy (MSA), and corticobasal degeneration (CBD) are forms of parkinsonism. PSP and CBD are 4R tauopathies and clinicopathologic overlaps exist between these two disorders. Neuropsychiatric symptoms including apathy, depression, anxiety are common features in patients with PSP and CBD. Disinhibition and impulsive behavior are also frequently observed in PSP patients, whereas hallucinations are seen only occasionally. Severe derangement in several neurotransmitter systems may account for behavioral symptoms observed in PSP and CBD, but substitutive therapy is not effective. Recent advances in genetics, epidemiology, biomarkers, pathophysiology, molecular mechanisms, and, in particular, the availability of treatments that may modify disease progression are opening new hopes in the care of these devastating disorders. MSA is a synucleinopathy with well characterized motor and autonomic dysfunction. MSA patients frequently show the presence of rapid eye movement (REM) behavior disorders, but the impact of neuropsychiatric disturbances and cognitive impairment in MSA needs further study. The availability of animal models and recent advances in the pathophysiology of α-synuclein accumulation are shedding light on the disease, opening new avenues for possible treatments.