Rohrer, Jonathan D.

Abstract INTRODUCTION The Genetic Frontotemporal Initiative (GENFI) and Advancing Research and Treatment in Frontotemporal Lobar Degeneration (ARTFL)‐Longitudinal Evaluation of Familial Frontotemporal Dementia Subjects (LEFFTDS) Longitudinal Frontotemporal Lobar Degeneration Study (ALLFTD) consortia developed Clinical Dementia Rating (CDR)‐derived scales with a motor domain to overcome systematic underestimation of disease severity by the CDR. We calculated disease severity scores using these scales in a mixed neurodegenerative cohort and correlated them with objective motor measures. METHODS The CDR plus National Alzheimer's Coordinating Center (NACC) Frontotemporal Lobar Degeneration (FTLD), CDR + NACC FTLD‐M (Motor), and Multidomain Impairment Rating (MIR) scores and motor measures were determined and correlated in 242 participants. RESULTS Both CDR + NACC FTLD‐M and MIR showed increased disease severity scores and correlated with motor measures. These findings were held in 81 amyotrophic lateral sclerosis (ALS) participants and correlated with the Revised Amyotrophic Lateral Sclerosis Functional Rating Scale. Including a motor domain required fewer study participants in a simulated clinical trial sample size calculation. DISCUSSION With a motor domain, CDR + NACC FTLD‐M and MIR improve disease severity classification and correlate with quantitative motor assessments. This addition more fully captures the extent of symptoms across the FTD‐ALS spectrum and improves clinical trial efficiency. Highlights CDR + NACC FTLD‐M and MIR strongly correlate with objective motor measures. The enhanced scales improve disease severity classification in FTD and ALS. Greater clinical trial efficiency is achieved using these enhanced scales.

AbstractINTRODUCTIONHigher male prevalence in sporadic behavioral variant frontotemporal dementia (bvFTD) has been reported. We hypothesized differences in phenotypes between genetic and sporadic bvFTD females resulting in underdiagnosis of sporadic bvFTD females.METHODSWe included genetic and sporadic bvFTD patients from two multicenter cohorts. We compared behavioral and cognitive symptoms, and gray matter volumes, between genetic and sporadic cases in each sex.RESULTSFemales with sporadic bvFTD showed worse compulsive behavior (p = 0.026) and language impairments (p = 0.024) compared to females with genetic bvFTD (n = 152). Genetic bvFTD females had smaller gray matter volumes than sporadic bvFTD females, particularly in the parietal lobe.DISCUSSIONFemales with sporadic bvFTD exhibit a distinct clinical phenotype compared to females with genetic bvFTD. This difference may explain the discrepancy in prevalence between genetic and sporadic cases, as some females without genetic mutations may be misdiagnosed due to atypical bvFTD symptom presentation.Highlights Sex ratio is equal in genetic behavioral variant of frontotemporal dementia (bvFTD), whereas more males are present in sporadic bvFTD. Distinct neuropsychiatric phenotypes exist between sporadic and genetic bvFTD in females. Phenotype might explain the sex ratio difference between sporadic and genetic cases.

AbstractBackgroundAutosomal dominant progranulin (GRN) mutations are a common genetic cause of frontotemporal lobar degeneration. Though clinical trials for GRN‐related therapies are underway, there is an unmet need for biomarkers that can predict symptom onset and track disease progression. We previously showed that presymptomatic GRN carriers exhibit thalamocortical hyperconnectivity that increases with age when they are presumably closer to symptom onset. However, whether hyperconnectivity arises concomitantly with markers of neurodegeneration remains unclear.MethodUtilizing T1 and task‐free functional magnetic resonance imaging (tf‐fMRI) from 49 presymptomatic and 26 symptomatic GRN mutation carriers, we determined the relationships between functional connectivity as measured by voxel‐wise whole brain degree and GRN‐relevant markers of disease progression, which included plasma neurofilament light chain (NfL) concentrations, CSF complement C1q and C3b protein levels, grey matter atrophy, and OCD symptom severity.ResultNfL concentrations were associated with frontotemporoparietal and thalamic hyperconnectivity in presymptomatic GRN carriers and extensive regions of atrophy in symptomatic carriers. Complement levels were associated with regions of hyperconnectivity, but not gray matter, in symptomatic carriers. Presymptomatic carriers with thalamic hyperconnectivity tended to have lower grey matter volume in bilateral insula and left lateral parietal cortex, which are among regions that deteriorate in GRN‐FTD. OCD symptom severity was associated with hypoconnectivity across all GRN carriers.ConclusionIn presymptomatic carriers, the co‐occurrence of hyperconnectivity, high NfL, and low gray matter suggests that tf‐fMRI hyperconnectivity may portend the onset of the neurodegenerative phase. These findings point toward hyperconnectivity as an indicator of approaching symptomatic onset.