Longitudinal decline in spoken word recognition and object knowledge in primary progressive aphasia

The premise of this study is that spoken word recognition and object knowledge are impaired in semantic variant primary progressive aphasia (PPA) (svPPA) and are spared in logopenic variant (lvPPA) and nonfluent agrammatic primary progressive aphasia (nfaPPA) at disease onset. Over time, however, there may be heterogeneity in these abilities in lvPPA and nfaPPA. We hypothesized that individuals with svPPA would demonstrate poorer performance on baseline spoken word recognition and object knowledge than those with lvPPA and nfaPPA) as documented in the literature, but that rates of decline over time on spoken word recognition and object knowledge would be similar in all 3 PPA variants because these become less distinguishable with disease progression. The aim of this study was to investigate longitudinal patterns of decline in spoken word recognition and object knowledge across PPA variants. Ninety-five individuals with PPA completed the Semantic Word Picture Matching and Semantic Associates tests at baseline to establish expected performance in these areas. Thirty-five individuals completed follow-up testing. The distributions of trichotomized mean rates of decline in object knowledge were similar for lvPPA and svPPA (P = .05). There were weak negative correlations between symptom duration and baseline scores on Semantic Word Picture Matching (r[37] = −0.399, P = .01), and baseline scores on Semantic Associates (r[37] = −0.394, P = .01) in lvPPA. Degradation of spoken word recognition and object knowledge occurs over time in lvPPA. Further investigation of the receptive language deficits in PPA is warranted to characterize language changes that lessen the distinctions between PPA variants with disease progression.