Neurobiology of aging
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Neurobiology of aging · Feb 2018
Multimodal MRI quantification of the common neurostructural bases within the FTD-ALS continuum.
The continuum hypothesis linking the behavioral variant of frontotemporal dementia (bvFTD) and amyotrophic lateral sclerosis (ALS) is supported by clinical, pathological, genetic, and neuroimaging evidence. In the present multimodal magnetic resonance study, we characterized the site and extent of shared neurostructural changes in gray and white matter in 20 bvFTD and 19 ALS patients without dementia. ⋯ The quantification of gray and white matter damage within the areas of shared alterations highlighted a higher degree of atrophy in orbitofrontal and frontomedial regions in patients with more severe executive and/or behavioral symptoms, and a higher degree of degeneration in the motor pathway in patients with more severe motor neuron disorders. Our finding provides additional evidence confirming the FTD-ALS continuum hypothesis and supports the notion of a bimodal but convergent pattern of neurostructural changes characterizing bvFTD and ALS.
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Neurobiology of aging · Feb 2018
Patterns of gray matter atrophy in genetic frontotemporal dementia: results from the GENFI study.
Frontotemporal dementia (FTD) is a highly heritable condition with multiple genetic causes. In this study, similarities and differences of gray matter (GM) atrophy patterns were assessed among 3 common forms of genetic FTD (mutations in C9orf72, GRN, and MAPT). Participants from the Genetic FTD Initiative (GENFI) cohort with a suitable volumetric T1 magnetic resonance imaging scan were included (319): 144 nonmutation carriers, 128 presymptomatic mutation carriers, and 47 clinically affected mutation carriers. ⋯ Presymptomatic GM atrophy was observed particularly in the thalamus and cerebellum in the C9orf72 group, the anterior and medial temporal lobes in MAPT, and the posterior frontal and parietal lobes as well as striatum in GRN. Across all presymptomatic carriers, there were significant decreases in the anterior insula. These results suggest that although there are important differences in atrophy patterns for each group (which can be seen presymptomatically), there are also similarities (a fronto-insula-anterior cingulate network) that help explain the clinical commonalities of the disease.