The structural correlates of functional deficits in early huntington's disease

Abstract

Neuropathological studies in Huntington disease (HD) have demonstrated neuronal loss in the striatum, as well as in other brain regions including the cortex. With diffusion tensor MRI we evaluated the hypothesis that the clinical dysfunction in HD is related to regionally specific lesions of circuit-specific cortico-basal ganglia networks rather than to the striatum only. We included 27 HD and 24 controls from the TRACK-HD Paris cohort. The following assessments were used: self-paced tapping tasks, trail B making test (TMT), University of Pennsylvania smell identification test (UPSIT), and apathy scores from the problem behaviors assessment. Group comparisons of fractional anisotropy and mean diffusivity and correlations were performed using voxel-based analysis. In the cortex, HD patients showed significant correlations between: (i) self paced tapping and mean diffusivity in the parietal lobe at 1.8 Hz and prefrontal areas at 3 Hz, (ii) UPSIT and mean diffusivity in the parietal, and median temporal lobes, the cingulum and the insula, and fractional anisotropy in the insula and the external capsule, (iii) TMT B and mean diffusivity in the white matter of the superior frontal, orbital, temporal, superior parietal and post central areas, and (iv) apathy and fractional anisotropy in the white matter of the rectus gyrus. In the basal ganglia, we found correlations between the self paced tapping, UPSIT, TMT tests, and mean diffusivity in the anterior part of the putamen and the caudate nucleus. In conclusion, disruption of motor, associative and limbic cortico-striatal circuits differentially contribute to the clinical signs of the disease.

Flavour identification in frontotemporal lobar degeneration

“…Abnormal eating behaviours are a cardinal feature of behavioural variant frontotemporal dementia (bvFTD) [13][14][15][16][17][18][19] : such abnormalities could be at least partly underpinned by deficits of flavour processing, and have been linked to cortical atrophy in a distributed network including the orbitofrontal cortex (OFC), anterior insula and striatum. [13][14][15][16][17][18][19] Overlapping grey matter correlates have been identified for odour identification performance in neurodegenerative diseases, [20][21][22] and these correlates align with the distributed frontotemporal-subcortical network implicated in flavour processing in functional imaging studies of the healthy brain. [2][3][4][5][6] Previous group analyses of patients with FTLD have examined processing of elementary taste qualities and recognition of the multimodal stimuli embodied in natural foods.…”

Beyond and below the cortex: the contribution of striatal dysfunction to cognition and behaviour in neurodegeneration

“…Still, cortical atrophy in combination with striatal atrophy has also been linked to cognitive symptoms in HD 58. Similarly, cortico-subcortical white matter tract changes have been associated with those deficits 59. Finally, functional imaging studies of cognitive changes in HD have consistently found cortical and striatal activation alterations compared with healthy controls in relation to cognitive load, planning, attention60 and more specifically, ventral striatal regions being related to reward processes 61.…”

The Evolving Role of Diffusion Magnetic Resonance Imaging in Movement Disorders

“…This level of accuracy was slightly higher than that (76%) found using machine learning approaches and voxel-based volumetric analysis [61]. Another study [62] found that motor and cognitive tasks were correlated with abnormal dMRI measures in multiple areas of GM and WM, suggesting that dysfunction in extra-striatal areas of the brain are related to clinical manifestations in a region-specific manner. Dumas and colleagues [53] found more widespread dMRI abnormalities in early manifesting compared to pre-manifesting HD, with correlations between dMRI and clinical measures.…”