Connectomic imaging in familial and sporadic frontotemporal degeneration

University Of Pennsylvania, Philadelphia PA

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Abstract

? DESCRIPTION (provided by applicant): Neurodegenerative disease is a major public health problem. Frontotemporal degeneration (FTD) is a clinical neurodegenerative condition that affects both gray matter (GM) and white matter (WM) and causes a network disorder. FTD is an excellent model for directly imaging the neurobiology of neurodegeneration because the associated pathology involves a monoproteinopathy in each patient - either frontotemporal lobar degeneration (FTLD) due to tau (FTLD-tau) or to TAR DNA binding protein of 43kD (FTLD-TDP). We propose a connectomic approach to identify FTLD-tau and FTLD-TDP in vivo. This is timely because of the discovery of disease-modifying agents, and pressing needs for accurate antemortem diagnosis, biomarkers to gauge response during treatment trials, and elucidation of mechanisms of disease progression even at the preclinical stage. About 25% of cases have familial FTD (fFTD) due to a small set of mutations causing one of these pathologies. The remaining 75% of cases have sporadic FTD (sFTD) with no definitive biomarkers for FTLD- tau or FTLD-TDP pathology. Preliminary data suggest that multimodal structural MRI (sMRI) of GM disease and diffusion MRI (dMRI) of WM disease can identify vulnerable networks in FTLD-tau and FTLD-TDP. We propose a five-site consortium, including Mayo Clinic, MGH/Harvard, Northwestern University, University of California in San Francisco, and University of Pennsylvania, to acquire HCP imaging in FTD. This will be linked to two NIH-funded biomarker registries, and this linkage will result in substantial cost savings. We propose three Specific Aims. In Year 01, Aim 1 will implement and validate the Human Connectome Project (HCP) Lifespan protocol for sMRI, dMRI, resting BOLD MRI (rs-fMRI), task-based functional MRI (tfMRI) and arterial spin labeling (ASL). We will acquire initial data, harmonize data between sites and with HCP, implement quality control procedures, optimize analyses using HCP and locally-developed pipelines, and implement data sharing procedures. In Year 02, Aim 2 will study presymptomatic and symptomatic fFTD associated with FTLD-tau or FTLD-TDP, and assess sFTD in specific phenotypes highly associated with FTLD-tau or FTLD-TDP. Connectomic imaging will be integrated with NIH-funded registries that acquire clinical, genetic and biofluid data. Based on histopathology showing greater WM disease in FTLD-tau than FTLD-TDP, we expect advanced HCP imaging to show partially distinct patterns in multimodal imaging of symptomatic as well as presymptomatic individuals with familial and sporadic FTLD-tau compared to FTLD-TDP. In Years 03-04, Aim 3 will acquire longitudinal data to assess competing hypotheses about mechanisms of disease spread in presymptomatic and symptomatic FTD. Consistent with animal studies, we expect that graph theoretic and multimodal network analyses will show disease spreading locally to adjacent brain regions, affecting different networks in FTLD-tau or FTLD-TDP.