Lexical and acoustic features in speech relating to Alzheimer's disease pathology

INTRODUCTION: Over 50% of logopenic variant primary progressive aphasia (lvPPA) cases are associated with AD pathology, yet their speech is not characterized compared to amnestic AD. In this study, we compared AD and lvPPA patients in a biologically confirmed cohort. METHODS: We extracted language variables with automated lexical and acoustic pipelines from oral picture descriptions produced by 44 AD and 21 lvPPA patients. RESULTS: LvPPA patients produced fewer verbs, adjectives, and more fillers with lower lexical diversity and higher pause rate than AD. Both groups showed some shared language impairments compared to HC, including more frequent and shorter words. Some of these measures were related to clinical test scores and CSF p-tau levels. DISCUSSION: Our speech measures captured subtle differences between the two phenotypes. Also, shared speech markers were linked to the common underlying pathology. This work demonstrates the potential of natural speech in detection of underlying AD pathology.