Basal Ganglia Pathology in ALS is Associated with Neuropsychological Deficits

Objectives: To evaluate basal ganglia changes along the amyotrophic lateral sclerosis (ALS)-ALS-frontotemporal dementia (FTD) continuum using multiple, complementary imaging techniques.

Methods: Sixty-seven C9orf72-negative patients with ALS and 39 healthy controls were included in a cross-sectional quantitative MRI study. Seven patients with ALS met criteria for comorbid behavioral variant FTD (ALS-FTD), 18 patients met the Strong criteria for cognitive and/or behavioral impairment (ALS-Plus), and 42 patients had no cognitive impairment (ALS-Nci). Volumetric, shape, and density analyses were performed for the thalamus, amygdala, nucleus accumbens, hippocampus, caudate nucleus, pallidum, and putamen.

Results: Significant basal ganglia volume differences were identified between the study groups. Shape analysis revealed distinct atrophy patterns in the amygdala in patients with ALS-Nci and in the hippocampus in patients with ALS-Plus in comparison with controls. Patients with ALS-FTD exhibited pathologic changes in the bilateral thalami, putamina, pallida, hippocampi, caudate, and accumbens nuclei in comparison with all other study groups. A preferential vulnerability has been identified within basal ganglia subregions, which connect directly to key cortical sites of ALS pathology. While the anatomical patterns were analogous, the degree of volumetric, shape, and density changes confirmed incremental pathology through the spectrum of ALS-Nci, ALS-Plus, to ALS-FTD. Performance on verbal memory tests correlated with hippocampal volumes, and accumbens nuclei volumes showed a negative correlation with apathy scores.

Conclusions: We demonstrate correlations between basal ganglia measures and structure-specific neuropsychological performance and a gradient of incremental basal ganglia pathology across the ALS-ALS-FTD spectrum, suggesting that the degree of subcortical gray matter pathology in C9orf72-negative ALS is closely associated with neuropsychological changes.