Semantic deficits in amyotrophic lateral sclerosis

Abstract

Our objective was to investigate, and establish neuroanatomical correlates of, semantic deficits in amyotrophic lateral sclerosis (ALS) and amyotrophic lateral sclerosis-frontotemporal dementia (ALS-FTD), compared to semantic dementia (SD) and controls. Semantic deficits were evaluated using a naming and semantic knowledge composite score, comprising verbal and non-verbal neuropsychological measures of single-word processing (confrontational naming, comprehension, and semantic association) from the Sydney Language Battery (SYDBAT) and Addenbrooke's Cognitive Examination – Revised (ACE-R). Voxel based morphometry (VBM) analysis was conducted using the region of interest approach. In total, 84 participants were recruited from a multidisciplinary research clinic in Sydney. Participants included 17 patients with ALS, 19 with ALS-FTD, 22 with SD and 26 age- and education-matched healthy controls. Significant semantic deficits were observed in ALS and ALS-FTD compared to controls. The severity of semantic deficits varied across the clinical phenotypes: ALS patients were less impaired than ALS-FTD patients, who in turn were not as impaired as SD patients. Anterior temporal lobe atrophy significantly correlated with semantic deficits. In conclusion, semantic impairment is a feature of ALS and ALS-FTD, and reflects the severity of temporal lobe pathology.

Key words::

• Dementia
• imaging
• cognition

Acknowledgements

We are also grateful to the research participants and their families for supporting ForeFront research.

Declaration of interest: This work was supported by funding from the Motor Neuron Disease Research Institute of Australia. Other funding was provided by Forefront, a collaborative research group dedicated to the study of frontotemporal dementia and motor neuron disease, from the National Health and Medical Research Council of Australia (NHMRC) program grant (APP1037746) and the Australian Research Council (ARC) Centre of Excellence in Cognition and its Disorders (CE110001021). FL was supported by an Australian Postgraduate Award (PhD scholarship); SH was supported by the Graham Linford Fellowship, Motor Neurone Disease Research Institute of Australia; EM and JRB were supported by NHMRC Early Career Fellowships; MH was supported by an ARC Research Fellowship; JRH was supported by an ARC Federation Fellowship. The authors alone are responsible for the content and writing of the paper.

Supplementary material available online

Supplementary Figure 1 and Appendix 1.