Digital Speech Analysis in Progressive Supranuclear Palsy and Corticobasal Syndromes

BackgroundProgressive supranuclear palsy and corticobasal syndromes (PSPS-CBS) as well as nonfluent/agrammatic primary progressive aphasia (naPPA) are often due to misfolded 4-repeat Tau, but the diversity of the associated speech disorders beyond Apraxia of Speech (AoS) is poorly understood.ObjectiveInvestigate the full range of acoustic and lexical properties of speech to test the hypothesis that PSPS-CBS show a subset of speech impairments found in naPPA.MethodsAcoustic and lexical measures, extracted from natural, digitized semi-structured speech samples using novel, automated methods, were compared in PSPS-CBS (n=87), naPPA (n=25) and healthy controls (HC, n=41). We also explored speech in a group of PSPS-CBS patients with concomitant naPPA (PSPS-CBS+naPPA, n=8). We related these measures to grammatical performance and speech fluency, core features of naPPA, and to cerebrospinal fluid (CSF) phosphorylated tau (pTau) in patients with available biofluid.ResultsBoth naPPA and PSPS-CBS speech had shorter speech segments, longer pauses, higher pause rate, reduced fundamental frequency (f0) range, and slower speech rate compared to HC. naPPA speech was distinct from PSPS-CBS with shorter speech segments, more frequent pauses, slower speech rate, and reduced verb production. In both groups, acoustic duration measures generally correlated with speech fluency and grammatical performance. PSPS-CBS+naPPA resembled naPPA in most speech measures and had the narrowest f0 range. CSF pTau levels correlated with f0 range and verb production in PSPS-CBS and naPPA.ConclusionThe speech pattern of PSPS-CBS overlaps that of naPPA apart from AoS, and may be related to CSF pTau.