Utility of Cortical Atrophy in Functional Networks as a Predictor of Progression in bvFTD

Abstract

AbstractBackgroundBehavioral variant frontotemporal dementia (bvFTD) is a clinically heterogeneous neurodegenerative disorder with variable rates of disease progression. Predictors of disease progression in bvFTD are significantly lacking, limiting the ability of clinical care planning. We recently showed that cortical atrophy in the frontoparietal control network (FPN) at baseline predicts the conversion to dementia in patients with Primary Progressive Aphasia (PPA). Leveraging this methodology, we hypothesized that FPN atrophy would predict progression of dementia in patients diagnosed with bvFTD.MethodWe analyzed data from 48 bvFTD patients (mean age 59.9 years, 20 Female) with very mild or mild dementia from our Frontotemporal Disorders Unit cohort and the Frontotemporal Lobar Degeneration Neuroimaging Initiative. Our primary outcome measure was change in the Clinical Dementia Rating‐FTLD Sum‐of‐Boxes (SoB) at baseline and at least one year later. Each participant underwent baseline MRI scanning for cortical thickness estimates. We ran a Pearson correlation analysis between the annualized change of CDR‐FTLD SoB from baseline to last observation, and baseline cortical network atrophy (quantified as network‐wise W scores). Vertex‐wise GLM analyses and network‐wise bivariate correlation analyses were also used to assess the relationship between network cortical atrophy and annualized CDR changes.ResultOf the 7 networks investigated, only FPN atrophy predicted annualized change in CDR‐FTLD SoB scores (r = ‐0.31, p = 0.03). That is, in bvFTD patients at the very mild/mild dementia stage, the greater the baseline FPN atrophy, the more rapid the clinical decline. Vertex‐wise GLM maps did not show that atrophy across the entire FPN predicted clinical decline. Rather, baseline atrophy in the dorsal precuneus and supramarginal gyrus nodes of the FPN was most predictive of clinical disease progression.ConclusionCortical atrophy in the FPN, and particularly in posterior regions of this network, is predictive of the rate of clinical decline in bvFTD patients, possibly due to the critical roles this network serves in executive function and affective regulation. This work could promote the use of structural imaging biomarkers to guide prognostication for bvFTD patients and their families, and to inform the design of clinical trials.