Forsberg, Leah K.

Abstract Objective Rapid eye movement (REM) sleep behavior disorder (RBD) is widely considered a prodromal synucleinopathy, as most with RBD develop overt synucleinopathy within ~10 years. Accordingly, RBD offers an opportunity to test potential treatments at the earliest stages of synucleinopathy. The North American Prodromal Synucleinopathy (NAPS) Consortium has created a multisite RBD participant, primarily clinic‐based cohort to better understand characteristics at diagnosis, and in future work, identify predictors of phenoconversion, develop synucleinopathy biomarkers, and enable early stage clinical trial enrollment. Methods Participants ≥18 years of age with overnight polysomnogram‐confirmed RBD without Parkinson's disease, dementia, multiple system atrophy, or narcolepsy were enrolled from nine sites across North America (8/2018 to 4/2021). Data collection included family/personal history of RBD and standardized assessments of cognitive, motor, sensory, and autonomic function. Results Outcomes are primarily reported based on sex (361 total: n = 295 male, n = 66 female), and secondarily based on history of antidepressant use ( n = 200 with, n = 154 without; with correction for sex differences) and based on extent of synucleinopathy burden ( n = 56 defined as isolated RBD, n = 305 defined as RBD+ [i.e., exhibiting ≥1 abnormality]). Overall, these participants commonly demonstrated abnormalities in global cognition (MoCA; 38%), motor function (alternate tap test; 48%), sensory (BSIT; 57%), autonomic function (orthostatic hypotension, 38.8%), and anxiety/depression (BAI and PHQ‐9; 39.3% and 31%, respectively). Interpretation These RBD participants, assessed with extensive history, demographic, cognitive, motor, sensory, and autonomic function demonstrated a lack of sex differences and high frequency of concomitant neurological abnormalities. These participants will be valuable for future longitudinal study and neuroprotective clinical trials.

AbstractAlterations of cerebral glucose metabolism can be detected in patients with isolated rapid eye movement sleep behaviour disorder, a prodromal feature of neurodegenerative diseases with α-synuclein pathology. However, metabolic characteristics that determine clinical progression in isolated rapid eye movement sleep behaviour disorder and their association with other biomarkers need to be elucidated. We investigated the pattern of cerebral glucose metabolism on 18F-fluorodeoxyglucose PET in patients with isolated rapid eye movement sleep behaviour disorder, differentiating between those who clinically progressed and those who remained stable over time. Second, we studied the association between 18F-fluorodeoxyglucose PET and lower dopamine transporter availability in the putamen, another hallmark of synucleinopathies. Patients with isolated rapid eye movement sleep behaviour disorder from the Mayo Clinic Alzheimer’s Disease Research Center and Center for Sleep Medicine (n = 22) and age-and sex-matched clinically unimpaired controls (clinically unimpaired; n = 44) from the Mayo Clinic Study of Aging were included. All participants underwent 18F-fluorodeoxyglucose PET and dopamine transporter imaging with iodine 123-radiolabeled 2β-carbomethoxy-3β-(4-iodophenyl)-N-(3-fluoropropyl) nortropane on single-photon emission computerized tomography. A subset of patients with isolated rapid eye movement sleep behaviour disorder with follow-up evaluations (n = 17) was classified as isolated rapid eye movement sleep behaviour disorder progressors (n = 7) if they developed mild cognitive impairment or Parkinson’s disease; or isolated rapid eye movement sleep behaviour disorder stables (n = 10) if they remained with a diagnosis of isolated rapid eye movement sleep behaviour disorder with no cognitive impairment. Glucose metabolic abnormalities in isolated rapid eye movement sleep behaviour disorder were determined by comparing atlas-based regional 18F-fluorodeoxyglucose PET uptake between isolated rapid eye movement sleep behaviour disorder and clinically unimpaired. Associations between 18F-fluorodeoxyglucose PET and dopamine transporter availability in the putamen were analyzed with Pearson’s correlation within the nigrostriatal pathway structures and with voxel-based analysis in the cortex. Patients with isolated rapid eye movement sleep behaviour disorder had lower glucose metabolism in the substantia nigra, retrosplenial cortex, angular cortex, and thalamus, and higher metabolism in the amygdala and entorhinal cortex compared with clinically unimpaired. Patients with isolated rapid eye movement sleep behaviour disorder who clinically progressed over time were characterized by higher glucose metabolism in the amygdala and entorhinal cortex, and lower glucose metabolism in the cerebellum compared with clinically unimpaired. Lower dopamine transporter availability in the putamen was associated with higher glucose metabolism in the pallidum within the nigrostriatal pathway; and with higher 18F-fluorodeoxyglucose uptake in the amygdala, insula, and temporal pole on a voxel-based analysis, although these associations did not survive after correcting for multiple comparisons. Our findings suggest that cerebral glucose metabolism in isolated rapid eye movement sleep behaviour disorder is characterized by hypometabolism in regions frequently affected during the prodromal stage of synucleinopathies, potentially reflecting synaptic dysfunction. Hypermetabolism is also seen in isolated rapid eye movement sleep behaviour disorder, suggesting that synaptic metabolic disruptions may be leading to a lack of inhibition, compensatory mechanisms, or microglial activation, especially in regions associated with nigrostriatal degeneration.

AbstractIntroductionEmpathy relies on fronto‐cingular and temporal networks that are selectively vulnerable in behavioral variant frontotemporal dementia (bvFTD). This study modeled when in the disease process empathy changes begin, and how they progress.MethodsFour hundred thirty‐one individuals with asymptomatic genetic FTD (n = 114), genetic and sporadic bvFTD (n = 317), and 163 asymptomatic non‐carrier controls were enrolled. In sub‐samples, we investigated empathy measured by the informant‐based Interpersonal Reactivity Index (IRI) at each disease stage and over time (n = 91), and its correspondence to underlying atrophy (n = 51).ResultsEmpathic concern (estimate = 4.38, 95% confidence interval [CI] = 2.79, 5.97; p < 0.001) and perspective taking (estimate = 5.64, 95% CI = 3.81, 7.48; p < 0.001) scores declined between the asymptomatic and very mild symptomatic stages regardless of pathogenic variant status. More rapid loss of empathy corresponded with subcortical atrophy.DiscussionLoss of empathy is an early and progressive symptom of bvFTD that is measurable by IRI informant ratings and can be used to monitor behavior in neuropsychiatry practice and treatment trials.

AbstractBackgroundβ‐amyloid plaques, a pathological hallmark of Alzheimer’s disease, are common in dementia with Lewy bodies (DLB). However, little is known about when β‐amyloid levels increase throughout the Lewy body disease (LBD) continuum, from an early prodromal stage of isolated REM sleep behavior disorder (iRBD), to a stage of mild cognitive impairment‐Lewy bodies (MCI‐LB), and finally DLB. Our objective was to investigate β‐amyloid deposition throughout the LBD continuum, as well as the influence of sex and APOE ε4 status, as potential factors contributing to Alzheimer’s disease pathological changes.MethodPatients with iRBD (n=24), MCI‐LB (n=62), and DLB (n=82) from the Mayo Clinic Alzheimer’s Disease Research Center and Center for Sleep Medicine were included. β‐amyloid levels were measured by Pittsburgh compound B (PiB) PET and global cortical standard uptake value ratio (SUVR) was calculated. Global cortical PiB SUVR values from each clinical group were compared to each other and to cognitively unimpaired individuals (CU; n=100) balanced on age and sex from the Mayo Clinic Study of Aging (MCSA). Clinical groups were compared using ANCOVA after adjusting by age.ResultMCI‐LB and DLB patients had significantly higher global cortical PiB SUVR than CU participants, while PiB SUVR in iRBD patients was comparable to that of CU participants (Figure 1). DLB patients also had significantly higher global cortical PiB SUVR compared to iRBD patients (p=0.004). In MCI‐LB and DLB, global cortical PiB SUVR was higher in APOE ε4 carriers compared to APOE ε4 non‐carriers (p<0.001), and women had higher global cortical PiB SUVR compared to men (p=0.024).ConclusionIn this cross‐sectional study, β‐amyloid pathology gradually increased throughout the clinically defined LBD continuum. Whereas β‐amyloid levels are comparable to cognitively unimpaired individuals in iRBD, a significant elevation in β‐amyloid levels coincides with cognitive impairment observed in MCI‐LB and DLB. Specifically, women and APOE ε4 carriers tend to have higher β‐amyloid levels than men and APOE ε4 non‐carriers. These findings have important implications for targeting patients within the LBD continuum, who may benefit from amyloid modifying therapies.

AbstractBackgroundReduced striatal uptake on ioflupane SPECT is considered an indicative biomarker for Dementia with Lewy Bodies (DLB), and has been proposed as an indicative biomarker for Mild Cognitive Impairment with Lewy Bodies (MCI‐LB). Little data exists on the profile of uptake on key striatal regions of interest (ROIs) in DLB or MCI‐LB.MethodParticipants with DLB or MCI‐LB at baseline based on the presence of ≥2 core clinical DLB features, and ≥2 ioflupane SPECT scans performed approximately annually, were identified from the Mayo ADRC database. Minimum brain laterality z‐score values for the putamen (whole, anterior and posterior), caudate and striatum were determined using DaTQUANT 2 software. Baseline clinical and scan data was used for all analyses, and the annualized minimum putamen z‐change was determined on serial scans. The scan was considered abnormal if the minimum putamen z‐score was <‐0.98 based on clinicopathologic data.Result27 participants were included (21 DLB and 6 MCI‐LB, 96% male). Compared to MCI‐LB, DLB had a lower mean MoCA score and a trend toward a higher UPDRS score compared to MCI‐LB; there were no statistically significant differences in age, sex, onset age or duration of cognitive decline, or presence of other core DLB features. The majority (89%) had an abnormal scan at baseline. All ROI z‐scores showed the expected general trend of DLB<MCI‐LB, and the annualized z‐change was more negative in DLB, but none of the findings reached statistical significance.ConclusionThese findings suggest in MCI‐LB and DLB that 1) an abnormal ioflupane SPECT scan is frequently present at diagnosis, 2) z‐scores become more negative over time, and 3) the annualized z‐change is similar. Similar findings in larger cohorts would support the use of ioflupane SPECT as a biomarker in both MCI‐LB and DLB clinical trials.

AbstractBackgroundIn familial frontotemporal lobar degeneration (f‐FTLD), plasma levels of neurofilament light (NfL) are elevated at least two years prior to symptom onset and predict future clinical status. The Neurofilament Surveillance Project (NSP), an actively recruiting observational study, seeks to obtain higher resolution data of temporal changes in plasma NfL to better understand its clinical utility in f‐FTLD interventional trials. The NSP is a pre‐competitive collaboration sponsored by the Bluefield Project to Cure FTD and funded by biotechnology and pharmaceutical companies and nonprofit organizations.MethodParticipants must be members of families with disease‐causing mutations in C9orf72, MAPT or GRN and enrolled in the ALLFTD natural history study. Up to 335 participants, with roughly equal representation across mutation type, provide plasma quarterly for 3 years (4355 samples total) to enable the observation of peripheral NfL levels longitudinally during disease onset and progression. Plasma is collected by certified mobile research nurses during remote visits, and NfL is measured in batch at least every 6 months. NfL measurements from one plasma aliquot per draw will be correlated with annual assessments obtained in the ALLFTD study, including measures of disease severity (CDRÒ+NACC‐FTLD, CGI, etc.), cognitive function from the UDS Neuropsychology Battery, and volumetric MRI data. Additional plasma aliquots are reserved for future analyses of other biomarkers during the course of the study; another subset of aliquots is reserved to share with interested investigators after the study ends.ResultAs of 1/19/22, the NSP had enrolled 161 participants, including 62 from C9orf72 kindreds, 60 from MAPT kindreds, and 28 from GRN kindreds. One‐hundred forty‐five participants had completed their initial visit, and 109 had completed more than 3, and up to 5, quarterly blood draws. Enrollment and study visits are ongoing despite COVID‐related limitations.ConclusionThe quarterly blood sampling from this study, combined with annual comprehensive clinical assessments through the ALLFTD natural history study, will enable a more detailed understanding of when and how NfL levels change during phenoconversion and/or disease progression in f‐FTLD mutation carriers. These data will be especially informative in the context of the targeted investigational therapeutics for f‐FTLD now entering clinical trials.

AbstractBackgroundMotor disturbances are common in patients with a variety of neurodegenerative and neurological syndromes, such as Parkinson’s disease and Frontotemporal Dementia (FTD). Accurately quantifying motoric changes could enable earlier detection and monitoring of these syndromes, and remote quantification may allow for more frequent assessments and may improve access to research for underrepresented and geographically dispersed participants. With these benefits in mind, investigators from the ALLFTD consortium developed smartphone tests of balance and finger tapping speed. Here we present preliminary test‐retest reliability and associations with gold standard tests.MethodThe tasks were analyzed in two independent samples. The first was an in‐person cohort of healthy older adults (n = 7), mild cognitive impairment (MCI, n = 1) and FTD (n = 3) who completed the smartphone standing/balance and finger tapping tests (FTT) twice in person. The second sample included 31 ALLFTD participants with a range of clinical presentations (healthy older adults [n = 11], FTD [n = 5], MCI [n = 2], unknown [n = 13]) who were asked to complete the balance test three times over two weeks at home. The primary outcomes were total taps for the FTT and root mean squared acceleration for the balance test. Test‐retest reliability was calculated using an intraclass correlation coefficient (ICC); given the small sample size, outliers (n = 6) were removed from the balance test. We tested the association of smartphone FTT with the gold standard mechanical FTT and the balance task with the CDR®+NACC‐FTLD‐SB (disease severity) using Spearman’s correlations. A Wilcoxon‐sign rank test compared participants with motor features on the Progressive Supranuclear Palsy Rating Scale (PSPRS>0) to those without (PSPRS = 0).ResultThe smartphone FTT showed good test‐retest reliability (ICC = 0.78) and a strong correlation (r = 0.8,p<0.05) with mechanical FTT. The test‐retest reliability for the balance task was excellent for the remote sample (ICC = 0.97) and in‐person (ICC = 0.89) samples. In the remote sample, greater acceleration was correlated with higher CDR®+NACC‐FTLD‐SB (r = 0.7,p = 0.003), and participants with motor features on the PSPRS had higher acceleration than those without (W = 11,p = 0.04).ConclusionThese findings provide preliminary support for the reliability and validity of the ALLFTD Mobile App tests of motor function. Replication in a larger sample is required.

AbstractBackgroundFrontotemporal dementia (FTD) is a collection of neurodegenerative diseases affecting behavior, cognition, and motor functions. FTD treatment trials will benefit from sensitive assessments capable of detecting and longitudinally tracking cognitive changes. Remote smartphone cognitive tests may improve the sensitivity to detect and monitor cognitive decline via novel methods of data capture and more frequent assessments within ecologically valid environments, while simultaneously reducing patient burden. The first step in determining the utility of these measures is establishing their reliability. We previously reported baseline reliability estimates for the ALLFTD Mobile App cognitive tests in a small pilot sample. Here we extend these results using a larger sample and evaluate six‐month stability.MethodWe enrolled a diagnostically mixed sample of 128 participants (CDR®+NACC‐FTLD = 0 [n = 84]; CDR®+NACC‐FTLD = 0.5 [n = 21]; CDR®+NACC‐FTLD≥1 [n = 23]) from ongoing studies of healthy aging (Hillblom Network) and frontotemporal dementia (ALLFTD). Participants self‐administered five cognitive tests from the ALLFTD Mobile App on their own smartphone; they were asked to complete each test three times within two weeks. Tests included gamified versions of N‐back, Stroop, Flanker, and Go/No‐Go paradigms, and an adaptive short‐term memory test. We evaluated the internal consistency of each test’s first occurrence using Spearman‐Brown split‐half reliability (100 simulations). Test‐retest reliability over the first three baseline replicates (as available) was evaluated by calculating intraclass correlations (ICC). In a preliminary analysis, we tested the six‐month stability of test performance in nine functionally intact participants who completed baseline and follow‐up Flanker, N‐Back, and adaptive memory assessments by calculating Spearman’s rho.ResultSplit‐half reliability estimates were in the good to excellent range (r’s: 0.81–0.97). Test‐retest reliability estimates were in the adequate to excellent range (ICCs: 0.72–0.96). ICC estimates were comparable for participants with and without clinical impairment (CDR®+NACC‐FTLD = 0 (0.74–0.95) and CDR®+NACC‐FTLD >0 (0.67–0.95). Among functionally intact individuals, baseline and 6‐months scores were highly correlated (r’s: 0.76–0.93, p’s<.05).ConclusionOur findings of adequate to excellent internal consistency, test‐retest reliability, and 6‐month stability support the feasibility of remote, smartphone‐based cognitive testing among a diagnostically mixed sample typical of healthy aging and frontotemporal dementia research studies.

AbstractBackgroundRemote digital cognitive assessments validated for use in frontotemporal dementia (FTD) and other neurodegenerative diseases would benefit clinical trials and clinical care. The ALLFTD Mobile App includes several smartphone‐based measures of cognition, and prior studies have provided preliminary support for their reliability. Here we evaluate their validity by testing associations with gold standard clinical outcomes and expected neural correlates.MethodA diagnostically mixed sample of 92 participants (CDR®+NACC‐FTLD = 0 [n = 33]; CDR®+NACC‐FTLD = 0.5 [n = 15]; CDR®+NACC‐FTLD≥1 [n = 16]; unknown [n = 28]) were recruited from a UCSF healthy aging study (Hillblom Network) and a North American FTD study (ALLFTD). Participants were asked to remotely complete four ALLFTD Mobile App tests of executive functioning (EF) and a memory test on their smartphones. Gold standard clinical measures were also collected; outcomes were the UDSv3 EF composite, CVLT‐SF Total Immediate Recall (memory), and CDR®+NACC‐FTLD Box Score (disease severity). Volumetric brain MRI measurements were available for a subset (n = 37). Expected neural correlates were frontoparietal gray matter volume for EF tests and hippocampal volume for the memory test. Linear models were fitted to evaluate the association of app tests with the gold standard outcomes, controlling for education, sex, and total intracranial volume (imaging only).ResultSmartphone EF measures were strongly and positively associated with the UDS3‐EF composite (ß’s = 0.6–0.8, all p<.001). The memory test was strongly correlated with the CVLT‐SF (ß = 0.7, p<.001). Tests were less strongly associated with divergent cognitive domains (e.g., associations with a visuospatial test were ß’s = 0.1–0.3). Worse performance on all tests was significantly associated with greater disease severity (ß’s = 0.5–0.7, all p<.001). Worse app‐based EF scores were associated with lower frontoparietal volume (ß’s = 0.4–0.6, all p<.015) and worse memory scores with lower hippocampal volume (ß = 0.5, p<.001).ConclusionALLFTD Mobile App scores were strongly associated with gold standard neuropsychological tests of the same cognitive domain (i.e., convergent validity) and less associated with measures of a different domain (i.e., divergent validity). Worse performance on the smartphone tests was associated with increasing disease severity and volume loss in expected brain regions. These results provide preliminary support for the construct validity of the ALLFTD Mobile App cognitive tests.