Visuospatial short-term and working memory disturbance in the primary progressive aphasias: Neuroanatomical and clinical implications.

INTRODUCTION: Primary progressive aphasia (PPA) comprises three main variants: logopenic (lv-PPA), non-fluent (nfv-PPA) and semantic variant (sv-PPA). Differentiating the language profiles of the PPA variants remains challenging, especially for lv-PPA and nfv-PPA. As such, diagnostic tools that do not rely on speech and language may offer some utility. Here, we investigated the short-term and working memory profiles of the PPA variants and typical Alzheimer's disease (AD), with a particular interest in the visuospatial system. We hypothesised visuospatial short-term and working memory would be more compromised in lv-PPA and AD than in the other PPA variants, and that this would relate to degeneration of posterior temporoparietal brain regions. METHOD: Thirty-three lv-PPA, 26 nfv-PPA, 31 sv-PPA and 58 AD patients, and 45 matched healthy controls were recruited. All participants completed the WMS-III Spatial and Digit Span tasks and underwent a structural brain MRI for voxel-based morphometry analyses. RESULTS: Relative to Controls, Spatial Span Forward (SSF) performance was impaired in lv-PPA and AD but not in nfv-PPA or sv-PPA. In contrast, Digit Span Forward (DSF) performance was impaired in lv-PPA and nfv-PPA (to a similar level), and AD, but was relatively intact in sv-PPA. As expected, most backward span scores across both modalities were lower than forward span scores. Neuroimaging analyses revealed that SSF and SSB performance in all patients combined correlated with grey matter intensity decrease in several clusters located in temporo-parieto-occipital brain regions. Post-hoc group comparisons of these regions showed that grey matter loss was more extensive in the lv-PPA and AD groups than in the nfv-PPA and sv-PPA groups. CONCLUSIONS: The findings suggest that the visuospatial short-term and working memory profiles of the PPA variants are separable and likely reflect their distinct patterns of temporo-parieto-occipital brain atrophy.

Lexical retrieval treatment in primary progressive aphasia: An investigation of treatment duration in a heterogeneous case series.

Word-finding difficulty is typically an early and frustrating symptom of primary progressive aphasia (PPA), prompting investigations of lexical retrieval treatment in PPA. This study aimed to investigate immediate treatment gains following two versus four weeks of treatment, item generalisation, and maintenance of gains with ongoing treatment in a single case series of eight individuals with heterogeneous PPA presentations (three non-fluent/agrammatic, two logopenic, two semantic, and one mixed PPA). Three individuals made initial gains in picture naming and maintained them over 6 months or more with ongoing treatment. By contrast, three individuals made marginal initial gains but were unable to continue treatment, and two individuals did not make the typically-reported initial gains with two or four weeks of treatment. There was little evidence of generalisation to untreated items. Our results add to the evidence that daily home practice of Repetition and Reading in the Presence of a Picture over extended periods can increase and maintain retrieval of personally-relevant words in picture naming for some individuals with semantic or nonfluent/agrammatic variant PPA. Further research is needed into the factors associated with long-term treatment adherence and gains, and the factors associated with nonadherence to treatment.