Neurocognitive basis of repetition deficits in primary progressive aphasia

Abstract

Previous studies indicate that repetition is affected in primary progressive aphasia (PPA), particularly in the logopenic variant, due to limited auditory-verbal short-term memory (avSTM). We tested repetition of phrases varied by length (short, long) and meaning (meaningful, non-meaningful) in 58 participants (22 logopenic, 19 nonfluent, and 17 semantic variants) and 21 healthy controls using a modified Bayles repetition test. We evaluated the relation between cortical thickness and repetition performance and whether sub-scores could discriminate PPA variants. Logopenic participants showed impaired repetition across all phrases, specifically in repeating long phrases and any phrases that were non-meaningful. Nonfluent, semantic, and healthy control participants only had difficulty repeating long, non-meaningful phrases. Poor repetition of long phrases was associated with cortical thinning in left temporo-parietal areas across all variants, highlighting the importance of these areas in avSTM. Finally, Bayles repetition phrases can assist classification in PPA, discriminating logopenic from nonfluent/semantic participants with 89% accuracy.

A Meta-Analysis of Neuropsychological Functioning in the Logopenic Variant of Primary Progressive Aphasia: Comparison with the Semantic and Non-Fluent Variants

“…A sizeable number of studies administered and reported the total score of the widely used Repetition subtest of the Western Aphasia Battery, which combines repetition of words, phrases, and sentences. Lukic et al (2019) and others have noted that the final six sentences are the most difficult items and are sensitive to the repetition difficulties characteristics of lvPPA. However, since studies typically combine measures of varying complexity, future PPA studies that separate repetition scores by difficulty level and meaning will be important for improving the clinical utility of repetition measures in the differential diagnosis of PPA.…”

“…lvPPA patients show poorer performance on repetition tasks across different length conditions, with greater deficits observed for repetition of long phrases and non-meaningful phrases (Lukic et al, 2019). Based on this work, we generated an effect size for repetition deficits in lvPPA that excluded performance on simple and mixed repetition tasks.…”

Primary progressive aphasia: a model for neurodegenerative disease

“…1). Naming difficulties in lvPPA correlate with left middle temporal gyrus atrophy [66], whereas repetition deficits correlate with temporoparietal junction damage [67]. White matter damage in lvPPA is less severe than in nfvPPA and involves left dorsal parietal white matter tracts that connect frontal and posterior temporal regions [22] (Fig.…”

Neural substrates of verbal repetition deficits in primary progressive aphasia

“…Previous studies investigating repetition in PPA support the involvement of this temporoparietal phonological buffer in verbal repetition tasks (Amici et al, 2007;Rogalski et al, 2011;Leyton et al, 2012;Lukic et al, 2019). The current study seeks to extend this work to test for the involvement of an additional phonological content buffer in left pIFS in sentence repetition and digit span working memory tasks, as predicted by GODIVA model.…”

“…For example, the characteristic anterior temporal atrophy in svPPA is associated with single-word comprehension abilities, while distinctive left inferior frontal atrophy in nfvPPA correlates with measures of syntactic processing (Amici et al, 2007;Sapolsky et al, 2010;Rogalski et al, 2011). LvPPA is associated with cortical thinning in the temporoparietal junction, with atrophy here also correlated with sentence repetition abilities (Amici et al, 2007;Rogalski et al, 2011;Lukic et al, 2019).…”