Aged 1 Agrammatism Alzheimer Disease 1 Alzheimer disease 1 Amyloid 1 Aphasia 1 Aphasia, Primary Progressive 1 Article 1 Female 1 Humans 1 Language Tests 1 Logopenic 1 Logopenic aphasia 1 Male 1 Middle Aged 1 PET 1 Primary progressive aphasia 1 Semantics 1 Speech Perception 1 Syntax 1 adult 1 aged 1 amyloid beta protein 1 aphasia 1 brain atrophy 1 clinical article 1 clinical feature 1 controlled study 1 female 1 grammar 1