“Functional communication” refers to an individual’s ability to communicate effectively in his or her everyday environment, and thus is a paramount skill to monitor and target therapeutically in people with aphasia. However, traditional controlled-paradigm assessments commonly used in both research and clinical settings often fail to adequately capture this ability. In the current study, facets of functional communication were measured from picture-elicited speech samples from 70 individuals with mild primary progressive aphasia (PPA), including the three variants, and 31 age-matched controls. Building upon methods recently used by Berube et al. (2019), we measured the informativeness of speech by quantifying the content of each patient’s description that was relevant to a picture relative to the total amount of speech they produced. Importantly, form-based errors, such as mispronunciations of words, unusual word choices, or grammatical mistakes are not penalized in this approach. We found that the relative informativeness, or efficiency, of speech was preserved in non-fluent variant PPA patients as compared with controls, whereas the logopenic and semantic variant PPA patients produced significantly less informative output. Furthermore, reduced informativeness in the semantic variant is attributable to a lower production of content units and a propensity for self-referential tangents, whereas for the logopenic variant, a lower production of content units and relatively ”empty” speech and false starts contribute to this reduction. These findings demonstrate that functional communication impairment does not uniformly affect all the PPA variants and highlight the utility of naturalistic speech analysis for measuring the breakdown of functional communication in PPA.

Background: Posterior Cortical Atrophy (PCA) is a clinical syndrome marked by progressive visuospatial impairment, usually due to underlying Alzheimer’s disease. While reading and spelling deficits are recognized clinical features of this syndrome, the contributions of visuoperceptual versus linguistic deficits to these impairments are still unclear. Methods: To that end, we examined reading and spelling performance in 23 individuals from the Massachusetts General Hospital PCA cohort. Participants completed tests of reading from the Western Aphasia Battery and spelling to dictation from the Boston Diagnostic Aphasia Examination. A mixed-methods analysis included quantitative scoring and qualitative observations of visual behaviors, error patterns, and compensatory strategies. Results: Participants commonly demonstrated visual scanning errors, difficulty following multi-line text, and spelling errors reflecting both visual–perceptual and orthographic–linguistic breakdowns. Conclusions: Because reading and spelling in PCA are variably impaired cognitive skills driven by visual deficits and lexical vulnerability, assessments and interventions must account for deficits in both cognitive processes. Our findings highlight the vulnerability of reading and spelling in PCA and underscore the need for multimodal assessment strategies that account for the interplay of visual, phonological, and lexical processes. These insights can inform diagnosis and guide the development of accessible interventions tailored to optimize compensatory strategies to support functional language abilities.