Citations

AbstractIntroductionTau‐positron emission tomography (PET) imaging with AV1451 is sensitive to Alzheimer disease (AD)–related tau deposition in the brain. We (1) examined regional variation of average tau‐PET standardized uptake value ratios (SUVRs) in a young normal population (30–49 years) and corrected for the regional variability and (2) tested if the standardized values (z‐scores) scaled appropriately to capture regional Alzheimer‐specific (i.e., amyloid sensitive) tau‐PET changes in individuals aged 50+ years.MethodsWe identified 490 individuals (70 between 30–49 years as a reference group and 420 cognitively normal between 50–95 years of age) with tau‐PET and amyloid PET scans from the Mayo Clinic Study of Aging.ResultsThere was intrinsic regional variability in average tau‐PET SUVR with uptakes higher in some regions than others, even in the younger individuals who would have minimal or no neurofibrillary tangles. We corrected for this using region of interest–specific z‐scores based on the reference group. Amyloid and tau‐PET uptake were associated throughout the brain after adjusting for age, with the highest correlations in the medial temporal regions.DiscussionRegions with high‐average SUVR are not necessarily those with the greatest tau pathology. Standardization is therefore recommended. Standardization of the data “realigns” the data such that the regional tau z‐scores are informative of the disease process, that is, regions with high z‐scores now coincide with regions correlated with amyloid deposition. Medial temporal structures, specifically entorhinal cortex–tau, may be useful as an AD‐specific tau‐PET signature due to its sensitivity to amyloid.

Abnormalities in zinc homeostasis are indicated in many human diseases, including Alzheimer disease (AD). 63 Zn-zinc citrate was developed as a positron emission tomography (PET) imaging probe of zinc transport and used in a first-in-human study in 6 healthy elderly individuals and 6 patients with clinically confirmed AD. Dynamic PET imaging of the brain was performed for 30 minutes following intravenous administration of 63 Zn-zinc citrate (∼330 MBq). Subsequently, body PET images were acquired. Urine and venous blood were analyzed to give information on urinary excretion and pharmacokinetics. Regional cerebral 63 Zn clearances were compared with 11 C-Pittsburgh Compound B ( 11 C-PiB) and 18 F-fluorodeoxyglucose ( 18 F-FDG) imaging data. 63 Zn-zinc citrate was well tolerated in human participants with no adverse events monitored. Tissues of highest uptake were liver, pancreas, and kidney, with moderate uptake being seen in intestines, prostate (in males), thyroid, spleen, stomach, pituitary, and salivary glands. Moderate brain uptake was observed, and regional dependencies were observed in 63 Zn clearance kinetics in relationship with regions of high amyloid-β plaque burden ( 11 C-PiB) and 18 F-FDG hypometabolism. In conclusion, zinc transport was successfully imaged in human participants using the PET probe 63 Zn-zinc citrate. Primary sites of uptake in the digestive system accent the role of zinc in gastrointestinal function. Preliminary information on zinc kinetics in patients with AD evidenced regional differences in clearance rates in correspondence with regional amyloid-β pathology, warranting further imaging studies of zinc homeostasis in patients with AD.

AbstractIntroductionWe hypothesized that common Alzheimer's disease (AD)‐associated variants within the triggering receptor expressed on myeloid (TREM) gene cluster influence disease through gene expression.MethodsExpression microarrays on temporal cortex and cerebellum from ∼400 neuropathologically diagnosed subjects and two independent RNAseq replication cohorts were used for expression quantitative trait locus analysis.ResultsA variant within a DNase hypersensitive site 5′ of TREM2, rs9357347‐C, associates with reduced AD risk and increased TREML1 and TREM2 levels (uncorrected P = 6.3 × 10−3 and 4.6 × 10−2, respectively). Meta‐analysis on expression quantitative trait locus results from three independent data sets (n = 1006) confirmed these associations (uncorrected P = 3.4 × 10−2 and 3.5 × 10−3, Bonferroni‐corrected P = 6.7 × 10−2 and 7.1 × 10−3, respectively).DiscussionOur findings point to rs9357347 as a functional regulatory variant that contributes to a protective effect observed at the TREM locus in the International Genomics of Alzheimer's Project genome‐wide association study meta‐analysis and suggest concomitant increase in TREML1 and TREM2 brain levels as a potential mechanism for protection from AD.

Abstract Introduction The overall goal of the Alzheimer's Disease Neuroimaging Initiative (ADNI) is to validate biomarkers for Alzheimer's disease (AD) clinical trials. ADNI‐3, which began on August 1, 2016, is a 5‐year renewal of the current ADNI‐2 study. Methods ADNI‐3 will follow current and additional subjects with normal cognition, mild cognitive impairment, and AD using innovative technologies such as tau imaging, magnetic resonance imaging sequences for connectivity analyses, and a highly automated immunoassay platform and mass spectroscopy approach for cerebrospinal fluid biomarker analysis. A Systems Biology/pathway approach will be used to identify genetic factors for subject selection/enrichment. Amyloid positron emission tomography scanning will be standardized using the Centiloid method. The Brain Health Registry will help recruit subjects and monitor subject cognition. Results Multimodal analyses will provide insight into AD pathophysiology and disease progression. Discussion ADNI‐3 will aim to inform AD treatment trials and facilitate development of AD disease‐modifying treatments.

Objectives To determine the cross‐sectional association between cerebral amyloid‐beta (A β ) deposition and gait. Design Cross‐sectional. Setting Population‐based cohort study in Olmsted County, MN . Participants Cognitively normal individuals (n = 611), aged 50 to 69 years, enrolled in the Mayo Clinic Study of Aging with concurrent PiB‐ PET imaging and gait assessment. Participants with a history of stroke, alcoholism, Parkinson's disease, subdural hematoma, traumatic brain injury, or normal pressure hydrocephalus were excluded. Measurements PiB‐ PET SUVR was measured in prefrontal, orbitofrontal, parietal, temporal, anterior cingulate, posterior cingulate, and motor‐specific regions of interest ( ROI s). Gait parameters (speed, cadence, stride length, double support time, and intra‐individual stance time variability) were measured using GAITR ite ® instrumentation. Linear regression models were adjusted for age, sex, body mass index, education, APOE ε 4 allele, Charlson comorbidity index, and depression. In secondary analyses, we additionally adjusted for neurodegeneration (hippocampal volume, FDG PET SUVR , and cortical thickness) in AD ‐associated regions. Results In fully adjusted models including neuroimaging measures of neurodegeneration, higher PiB‐ PET SUVR across all ROI s was associated with slower gait speed ( P < .05 except for the parietal ROI ), lower cadence and longer double support time ( P ≤ .05 except for the motor ROI ), and greater stance time variability ( P < .05). In sex‐stratified analyses, the association between higher PiB‐ PET SUVR across all ROI s and measures of gait was only present among women. Conclusion PiB‐ PET SUVR across ROI s, independent of general measures of AD ‐associated neurodegeneration, is associated with poorer performance on multiple gait parameters among cognitively normal women, aged 50 to 69 years. Longitudinal studies are needed to determine whether A β predicts gait decline in both women and men.

ObjectivePatients with probable dementia with Lewy bodies (DLB) often have Alzheimer's disease (AD)‐related pathology. Our objective was to determine the pattern of positron emission tomography (PET) tau tracer AV‐1451 uptake in patients with probable DLB, compared to AD, and its relationship to β‐amyloid deposition on PET.MethodsConsecutive patients with clinically probable DLB (n = 19) from the Mayo Clinic Alzheimer's Disease Research Center underwent magnetic resonance imaging, AV‐1451, and Pittsburgh compound‐B (PiB) PET examinations. Age‐ and sex‐matched groups of AD dementia (n = 19) patients and clinically normal controls (n = 95) from an epidemiological cohort served as a comparison groups. Atlas‐ and voxel‐based analyses were performed.ResultsThe AD dementia group had significantly higher AV‐1451 uptake than the probable DLB group, and medial temporal uptake completely distinguished AD dementia from probable DLB. Patients with probable DLB had greater AV‐1451 uptake in the posterior temporoparietal and occipital cortex compared to clinically normal controls, and in probable DLB, the uptake in these regions correlated with global cortical PiB uptake (Spearman rho = 0.63; p = 0.006).InterpretationMedial temporal lobe AV‐1451 uptake distinguishes AD dementia from probable DLB, which may be useful for differential diagnosis. Elevated posterior temporoparietal and occipital AV‐1451 uptake in probable DLB and its association with global cortical PiB uptake suggest an atypical pattern of tau deposition in DLB. ANN NEUROL 2017;81:58–67

AimThe p.P301L mutation in microtubule‐associated protein tau (MAPT) is a common cause of frontotemporal dementia and parkinsonism linked to chromosome 17 (FTDP‐17). We compare clinicopathologic features of five unrelated and three related (brother, sister and cousin) patients with FTDP‐17 due to p.P301L mutation.MethodsGenealogical, clinical, neuropathologic and genetic data were reviewed from eight individuals.ResultsThe series consisted of five men and three women with an average age of death of 58 years (52–65 years) and average disease duration of 9 years (3–14 years). The first symptoms were those of behavioural variant frontotemporal dementia in seven patients and semantic variant of primary progressive aphasia in one. Three patients were homozygous for the MAPT H1 haplotype; five had H1/H2 genotype. The apolipoprotein E genotype was ϵ3/ϵ3 in seven and ϵ3/ϵ4 in one. The average brain weight was 1015 g (876–1188 g). All had frontotemporal lobar or more diffuse cortical atrophy. Except for one patient, the hippocampus and parahippocampal gyrus had minimal atrophy, whereas there was atrophy of middle and inferior temporal gyri. Dentate fascia neuronal dispersion was identified in three patients, two of whom had epilepsy. In one patient there was extensive white matter tau involvement with Gallyas‐positive globular glial inclusions typical of globular glial tauopathy (GGT).ConclusionsThis clinicopathologic study shows inter‐ and intra‐familial clinicopathologic heterogeneity of FTDP‐17 due to MAPT p.P301L mutation, including GGT in one patient.

Objectives To investigate the timing (mid‐ vs late life) of physical activity, apolipoprotein ( APO )E ε 4, and risk of incident mild cognitive impairment ( MCI ). Design Prospective cohort study. Setting Mayo Clinic Study of Aging (Olmsted County, MN ). Participants Cognitively normal elderly adults (N = 1,830, median age 78, 50.2% female). Measurements Light, moderate, and vigorous physical activities in mid‐ and late life were assessed using a validated questionnaire. An expert consensus panel measured MCI based on published criteria. Cox proportional hazards models were used to calculate hazard ratios ( HR s) and 95% confidence intervals ( CI s) with age as a time scale after adjusting for sex, education, medical comorbidity, and depression. Results Light ( HR = 0.58, 95% CI = 0.43–0.79) and vigorous ( HR = 0.78, 95% CI = 0.63–0.97) physical activity in midlife were associated with lower risk of incident MCI . The association between moderate activity and incident MCI was not significant ( HR = 0.85, 95% CI = 0.67–1.09). In late life, light ( HR = 0.75, 95% CI = 0.58–0.97) and moderate ( HR = 0.81, 95% CI = 0.66–0.99) but not vigorous physical activity were associated with lower risk of incident MCI . A synergistic interaction was also observed between mid‐ and late‐life activity in reducing risk of incident MCI . Furthermore, APOE ε 4 carriers who did not exercise had a higher risk of incident MCI than noncarriers who reported physical activity. Conclusion Physical activity reduced the risk of incident MCI . Exercising in mid‐ and late life had an additive synergistic interaction in reducing the risk of MCI .