13.: More than just dysarthria: Language dysfunction in motor neuron disease

Abstract

Motor neuron disease (MND) and frontotemporal dementia (FTD) share clinical, genetic, and pathological features. Executive and behavioural disturbances are now recognised in MND, but non-executive cognitive impairments such as language dysfunction – a characteristic clinical feature of FTD – have not been explored to our knowledge. The present study investigated language in MND using tools specifically designed for use in different FTD phenotypes, including semantic dementia (SD) and progressive non-fluent aphasia (PNFA). Specifically, semantic deficits were assessed and compared to SD, whereas ability to interpret grammar was compared to PNFA. The study was performed in two parts. In part A, the Sydney language battery was used to assess aspects of semantic knowledge such as object naming, and results were compared to SD. In part B, interpretation of grammar was assessed using the test of reception of grammar (TROG), and results were compared to PNFA. Voxel-based morphometry was used to correlate patterns of cortical atrophy with performance on language measures. In total, 84 participants were included in part A (17 MND, 19 FTD-MND, 22 SD, and 26 controls) and 71 participants in part B (18 MND, 16 FTD-MND, 28 PNFA, and 9 controls). Part A demonstrated semantic deficits in MND and FTD-MND. For example, MND and FTD-MND were impaired on object naming (MND 25 ± 2.9, FTD-MND 17.1 ± 6.6, SD 5.4 ± 3.9, and controls 27 ± 1.9; p