Machulda, Mary M.

AbstractBackgroundLogopenic progressive aphasia (LPA) and posterior cortical atrophy (PCA) have distinct patterns of hypometabolism and atrophy. However, these clinical syndromes overlap: visuospatial impairment has been documented in LPA and aphasia in PCA. Rey‐Osterrieth Complex Figure – Copy (Rey‐O Copy) performance is correlated with parietal‐occipital atrophy in LPA. We explore visuospatial impairment on the Rey‐O Copy in LPA and PCA with the Mayo Older Americans Normative Studies (MOANS; which uses Meyers & Meyers criteria) and the Boston Qualitative Scoring System (BQSS). We also examine the proportion of visuospatial impairment in LPA, an under‐appreciated phenomenon, compared to PCA wherein it is fundamental.MethodPatients with LPA (n=25) or PCA (n=23) were recruited by the Neurodegenerative Research Group. Patients underwent comprehensive neuropsychological testing (including Rey‐O Copy) at baseline visit. Cut‐offs of T‐score=40 (BQSS) or scaled score=7 (MOANS) were used based on normative data. Proportions of patients with low performance were examined across LPA and PCA groups. Individual logistic regressions and AUROC analyses were then conducted to quantify differences in visuospatial impairment in LPA and PCA with both scoring systems. Identical analyses were conducted using raw scores corrected for age and sex, to avoid confounds of adjustments in normative data.ResultLPA and PCA groups were comparable on age, sex, and disease duration (LPA Median = 2.7 years, IQR=1.9‐3.5; PCA Median = 3.6 years, IQR=1.5‐4.9); p=.823). Surprisingly, 52‐72% of LPA participants demonstrated impaired performance across scoring systems, relative to 96% of the PCA group identified by both scoring systems. Odds ratios (OR) for the Rey‐O Copy MOANS (OR = 1.59; p=.008) and BQSS Copy Presence and Accuracy index (CPA; OR = 1.13, p=.002) were significant, persisting for age‐ and sex‐ controlled raw scores, suggesting the odds of a PCA diagnosis increased with decrement on Rey‐O Copy. AUROC values ranged from 0.77 to 0.88 across these indices.ConclusionA substantial number of LPA participants showed visuospatial impairment, despite initial primary language complaints. Differentiation of diagnostic groups by the Rey‐O is likely underscored by relatively uniform, profound, visuospatial impairment in PCA with more variability in LPA. However, the degree of visuospatial impairment overlaps remarkably across diagnoses.

AbstractBackgroundThere have been no standard definitions of successful cognitive aging (SA). Our goal was to apply different SA definitions to the 80+ population in the Mayo Clinic Study of Aging (MCSA) on the basis of (i) cross‐sectional vs longitudinal cognition (“Exceptionality” vs “Maintenance”) and (ii) memory vs global cognitive scores and explore the participant characteristics for each SA definition on the basis of baseline imaging markers and mid/late‐life health.MethodWe included 2157 participants from the MCSA, all ≥80 years at baseline and classified them into two SA definitions using memory z‐scores or global z‐scores: “Exceptionality” when high cognitive performance was observed (z‐scores ≥ 1 SD), “Maintenance” when cognitive function was preserved over time (Slope ≥ ‐0.1/year using mixed‐effect models). Our imaging markers were: PET‐based amyloid positivity (A+), MRI‐based neurodegeneration positivity (N+), WMH, FDG‐PET SUVR markers of resilience (anterior cingulate, ACC) and AD‐related areas (posterior cingulate). We also examined APOE4 status and other health characteristics. Group comparison was performed within each definition (e.g. exceptional vs non‐exceptional memory) using ANCOVA and binary logistic regressions with adjustments for age, sex, and education.ResultA lower number of participants met the “Exceptionality” criteria (10%: memory and 4%: global). A greater number met the “Maintenance” criteria (53%: memory and 32%: global). Less than 7% showed both “Exceptional” cognition and “Maintenance” over time. Participants across SA definitions were in general younger, more often women, with a higher education/occupation and less often APOE4 carriers. All SA groups showed higher ACC metabolism and lower N+ compared to the corresponding non‐SA group. More than 50% of the participants in the “Exceptional” groups were A+ (57%: memory, 50%: global). A+ frequency was significantly lower in the “Maintainers” (<42%). Better mid/late‐life health indicators were observed in the SA groups, including lower cardio‐metabolic conditions, higher mid‐life cognitive activities, lower depressive symptomatology, lower hypersomnolence and better self‐perception of health.ConclusionDifferent SA definitions identified mainly non‐overlapping 80+ groups that showed several common features including higher education/occupation, percent of women, better lifestyles, lower N+ frequency, and higher ACC metabolism. Lower A+ frequency was a key distinct feature of “Maintenance”.

AbstractBackgroundEarly changes in white matter (WM) measured using diffusion tensor imaging (DTI) are sensitive markers of WM degeneration and predict future cognitive decline in mild cognitive impairment (MCI). We sought to examine whether changes in WM integrity differed among empirically derived subtypes of incident MCI.MethodParticipants included 66 individuals with incident MCI enrolled in the population‐based Mayo Clinic Study of Aging (MCSA) previously identified via cluster analysis as having one of four MCI subtypes: subtle cognitive impairment (SCI; n = 13, mean age 78; 15% women), amnestic (n = 24; mean age 79; 54% women), dysnomic (n = 8; mean age 79; 38% women), and dysexecutive (n = 21; mean age 82; 33% women). All participants completed 3T MRI at the time of the MCI diagnosis. We compared the MCI subtypes to 100 cognitively unimpaired (CU) participants (mean age 77; 49% women). We used tract‐based spatial statistics to examine voxel‐level differences in fractional anisotropy (FA). We also fit a linear regression model to regional FA data from the corpus callosum (CC), the major interhemispheric WM connection, to quantify the relative differences in WM damage.ResultAll MCI subtypes except the subtle cognitive impairment group had widespread decreased FA. Relative to CU, the amnestic cluster showed decreased FA in the CC (genu), cingulum, fornix and uncinate fasciculus (UF); the dysnomic cluster showed decreased FA in the CC (genu, splenium), fornix, UF, anterior thalamic radiation (ATR), and corticospinal tract (CST); and the dysexecutive group showed decreased FA in the CC (genu, body, splenium), cingulum, UF, ATR, CST, and superior longitudinal fasciculus. The dysexecutive cluster had the most severe bilateral involvement among all MCI subtypes. The regional analysis showed that the amnestic, dysnomic, and dysexecutive groups (but not the subtle cognitive impairment group) had significantly lower FA of the CC compared to CU (p<0.001; Figure 1).ConclusionWe found widespread WM degeneration in the commissural and long association fibers in amnestic, dysnomic, and dysexecutive incident MCI subtypes. The extent of CC damage seen in Figure 1. confirmed the voxel‐level results and suggests that interhemispheric WM disconnection is relevant to the development of MCI.

AbstractBackgroundMagnetic resonance brainstem measurements are useful structural biomarkers in the Richardson's syndrome variant of progressive supranuclear palsy (PSP). However, it is unclear how these biomarkers differ across the phenotypic spectrum of PSP and how they relate to underlying pathology.ObjectiveThe aim of this study was to compare brainstem imaging measures across clinical variants of PSP and determine sensitivity and specificity based on pathologically diagnosed cases.MethodsA total of 153 patients with PSP who represented eight clinical variants were recruited at Mayo Clinic (Rochester, MN, USA) and underwent structural magnetic resonance imaging (MRI). Midbrain and pons area and superior and middle cerebellar peduncle width measurements were performed, and midbrain/pons ratio and Magnetic Resonance Parkinsonism Index (MRPI) were calculated. Among the 43 patients who later died, PSP pathology was confirmed in 29, whereas 14 had other pathology.ResultsBrainstem measurements varied across PSP clinical variants and were most abnormal in PSP‐Richardson's syndrome and frontal variants, followed by PSP‐corticobasal, PSP‐speech/language, and PSP‐parkinsonism variants. All these variants showed abnormalities compared with controls. The PSP‐gait freezing variant and patients with prominent corticospinal tract signs showed normal brainstem measures. Among cases with confirmed PSP pathology, the midbrain area, midbrain/pons ratio, and MRPI were all more abnormal compared to those with other pathologies, with best differentiation obtained with the MRPI (sensitivity = 83%; specificity = 85%).ConclusionsMRI brainstem measures show utility as diagnostic biomarkers across PSP clinical variants and have the potential to be useful in predicting underlying pathology. © 2021 International Parkinson and Movement Disorder Society

ABSTRACTBackgroundProgressive supranuclear palsy (PSP) may present as a speech/language disorder (PSP‐SL).ObjectiveWe assessed pathological correlates of patients with PSP‐SL who retained the suggestive of PSP‐SL (s.o. PSP‐SL) diagnosis versus those who progressed to possible/probable (poss./prob.) PSP.MethodsThirty‐four prospectively recruited patient with s.o. PSP‐SL completed comprehensive speech/language and neurological assessments longitudinally, died, and underwent autopsy.ResultsTwelve patients (35%) evolved to poss./prob PSP, while 22 (65%) remained as s.o. PSP‐SL. Pathological diagnoses differed across the groups (P = 0.025). Patients with s.o. PSP‐SL had four different neuropathologies (corticobasal degeneration [59%], PSP [13%], Pick's disease [14%], and frontotemporal lobar degeneration with TDP‐43 [14%]), while all patients with poss./prob. PSP had a 4R‐tauopathy (PSP [67%] and corticobasal degeneration [33%]). Development of poss./prob. PSP increased the chance of having PSP pathology by 2.38 times.ConclusionsPSP‐SL is associated with heterogenous pathologies. Evolution of PSP‐SL into poss./prob. PSP is more predictive of underlying PSP pathology than s.o. PSP‐SL. © 2021 International Parkinson and Movement Disorder Society

AbstractIntroductionBlood‐based biomarkers of amyloid pathology and neurodegeneration are entering clinical use. It is critical to understand what factors affect the levels of these markers.MethodsPlasma markers (Aβ42, Aβ40, NfL, T‐tau, Aβ42/40 ratio) were measured on the Quanterix Simoa HD‐1 analyzer for 996 Mayo Clinic Study of Aging (MCSA) participants, aged 51 to 95 years. All other data were collected during in‐person MCSA visits or abstracted from the medical record.ResultsAmong cognitively unimpaired (CU) participants, all plasma markers correlated with age. Linear regression models revealed multiple relationships. For example, higher Charlson Comorbidity Index and chronic kidney disease were associated with higher levels of all biomarkers. Some relationships differed between mild cognitive impairment and dementia participants.DiscussionMultiple variables affect plasma biomarkers of amyloid pathology and neurodegeneration among CU in the general population. Incorporating this information is critical for accurate interpretation of the biomarker levels and for the development of reference ranges.

Abstract Posterior cortical atrophy is a neurodegenerative syndrome with a heterogeneous clinical presentation due to variable involvement of the left, right, dorsal and ventral parts of the visual system, as well as inconsistent involvement of other cognitive domains and systems. 18F-fluorodeoxyglucose (FDG)-PET is a sensitive marker for regional brain damage or dysfunction, capable of capturing the pattern of neurodegeneration at the single-participant level. We aimed to leverage these inter-individual differences on FDG-PET imaging to better understand the associations of heterogeneity of posterior cortical atrophy. We identified 91 posterior cortical atrophy participants with FDG-PET data and abstracted demographic, neurologic, neuropsychological and Alzheimer’s disease biomarker data. The mean age at reported symptom onset was 59.3 (range: 45–72 years old), with an average disease duration of 4.2 years prior to FDG-PET scan, and a mean education of 15.0 years. Females were more common than males at 1.6:1. After standard preprocessing steps, the FDG-PET scans for the cohort were entered into an unsupervised machine learning algorithm which first creates a high-dimensional space of inter-individual covariance before performing an eigen-decomposition to arrive at a low-dimensional representation. Participant values (‘eigenbrains’ or latent vectors which represent principle axes of inter-individual variation) were then compared to the clinical and biomarker data. Eight eigenbrains explained over 50% of the inter-individual differences in FDG-PET uptake with left (eigenbrain 1) and right (eigenbrain 2) hemispheric lateralization representing 24% of the variance. Furthermore, eigenbrain-loads mapped onto clinical and neuropsychological data (i.e. aphasia, apraxia and global cognition were associated with the left hemispheric eigenbrain 1 and environmental agnosia and apperceptive prosopagnosia were associated with the right hemispheric eigenbrain 2), suggesting that they captured important axes of normal and abnormal brain function. We used NeuroSynth to characterize the eigenbrains through topic-based decoding, which supported the idea that the eigenbrains map onto a diverse set of cognitive functions. These eigenbrains captured important biological and pathophysiologic data (i.e. limbic predominant eigenbrain 4 patterns being associated with older age of onset compared to frontoparietal eigenbrain 7 patterns being associated with younger age of onset), suggesting that approaches that focus on inter-individual differences may be important to better understand the variability observed within a neurodegenerative syndrome like posterior cortical atrophy.

Background: Longitudinal, but not cross-sectional, cognitive testing is one option proposed to define transitional cognitive decline for individuals on the Alzheimer’s disease continuum. Objective: Compare diagnostic accuracy of cross-sectional subtle objective cognitive impairment (sOBJ) and longitudinal objective decline (ΔOBJ) over 30 months for identifying 1) cognitively unimpaired participants with preclinical Alzheimer’s disease defined by elevated brain amyloid and tau (A+T+) and 2) incident mild cognitive impairment (MCI) based on Cogstate One Card Learning (OCL) accuracy performance. Methods: Mayo Clinic Study of Aging cognitively unimpaired participants aged 50 + with amyloid and tau PET scans (n = 311) comprised the biomarker-defined sample. A case-control sample of participants aged 65 + remaining cognitively unimpaired for at least 30 months included 64 who subsequently developed MCI (incident MCI cases) and 184 controls, risk-set matched by age, sex, education, and visit number. sOBJ was assessed by OCL z-scores. ΔOBJ was assessed using within subjects’ standard deviation and annualized change from linear regression or linear mixed effects (LME) models. Concordance measures Area Under the ROC Curve (AUC) or C-statistic and odds ratios (OR) from conditional logistic regression models were derived. sOBJ and ΔOBJ were modeled jointly to compare methods. Results: sOBJ and ΔOBJ-LME methods differentiated A+T+ from A-T- (AUC = 0.64, 0.69) and controls from incident MCI (C-statistic = 0.59, 0.69) better than chance; other ΔOBJ methods did not. ΔOBJ-LME improved prediction of future MCI over baseline sOBJ (p = 0.003) but not over 30-month sOBJ (p = 0.09). Conclusion: Longitudinal decline did not offer substantial benefit over cross-sectional assessment in detecting preclinical Alzheimer’s disease or incident MCI.

AbstractIntroductionThe prognostic utility of cerebrospinal fluid (CSF) phosphorylated tau 217 (p‐tau217) and p‐tau181 is not understood.MethodsAnalyses included 753 Mayo Clinic Study on Aging participants (median age = 71.6; 57% male). CSF amyloid beta (Aβ)42 and p‐tau181 were measured with Elecsys immunoassays. CSF p‐tau181 and p‐tau217 were also measured with Meso Scale Discovery (MSD). We used Cox proportional hazards models for risk of mild cognitive impairment (MCI) and linear mixed models for risk of global and domain‐specific cognitive decline and cortical thickness. Analyses were stratified by elevated brain amyloid based on CSF Aβ42 or amyloid positron emission tomography for those with imaging.ResultsCSF p‐tau217 was superior to p‐tau181 for the diagnosis of Alzheimer's disease (AD) pathology. CSF MSD p‐tau181 and p‐tau217 were associated with risk of MCI among amyloid‐positive individuals. Differences between CSF p‐tau measures predicting cortical thickness were subtle.DiscussionThere are subtle differences for CSF p‐tau217 and p‐tau181 as prognostic AD markers.