ABSTRACT
PURPOSE: The aim of this study was to investigate the differences in early (EOAD) and late (LOAD) onset of Alzheimer´s disease, as well as glucose uptake, regional cerebral blood flow (R1), amyloid depositions, and functional brain connectivity between normal young (YC) and Old Controls (OC). METHODOLOGY: The study included 22 YC (37 ± 5 y), 22 OC (73 ± 5.9 y), 18 patients with EOAD (63 ± 9.5 y), and 18 with LOAD (70.6 ± 7.1 y). Patients underwent FDG and PIB PET/CT. R1 images were obtained from the compartmental analysis of the dynamic PIB acquisitions. Images were analyzed by a voxel-wise and a VOI-based approach. Functional connectivity was studied from the R1 and glucose uptake images. RESULTS: OC had a significant reduction of R1 and glucose uptake compared to YC, predominantly at the dorsolateral and mesial frontal cortex. EOAD and LOAD vs. OC showed a decreased R1 and glucose uptake at the posterior parietal cortex, precuneus, and posterior cingulum. EOAD vs. LOAD showed a reduction in glucose uptake and R1 at the occipital and parietal cortex and an increased at the mesial frontal and temporal cortex. There was a mild increase in an amyloid deposition at the frontal cortex in LOAD vs. EOAD. YC presented higher connectivity than OC in R1 but lower connectivity considering glucose uptake. Moreover, EOAD and LOAD showed a decreased connectivity compared to controls that were more pronounced in glucose uptake than R1. CONCLUSION: Our results demonstrated differences in amyloid deposition and functional imaging between groups and a differential pattern of functional connectivity in R1 and glucose uptake in each clinical condition. These findings provide new insights into the pathophysiological processes of AD and may have an impact on patient diagnostic evaluation.
Subject(s)
Alzheimer Disease , Aging , Alzheimer Disease/diagnostic imaging , Aniline Compounds , Brain/diagnostic imaging , Cerebrovascular Circulation , Glucose , Humans , Positron Emission Tomography Computed Tomography , Positron-Emission Tomography/methods , ThiazolesABSTRACT
ObjectiveCOVID-19 Living OVerview of Evidence (COVID-19 L{middle dot}OVE) is a public repository and classification platform for COVID-19 articles. The repository contains over 430,000 articles as of 20 September 2021 and intends to provide a one-stop shop for COVID-19 evidence. Considering that systematic reviews conduct high-quality searches, this study assesses the comprehensiveness and currency of the repository against the total number of studies in a representative sample of COVID-19 systematic reviews. MethodsOur sample was generated from all the studies included in the systematic reviews of COVID-19 published during April 2021. We estimated the comprehensiveness of COVID-19 L{middle dot}OVE repository by determining how many of the individual studies in the sample were included in the COVID-19 L{middle dot}OVE repository. We estimated the currency as the percentage of studies that were available in the COVID-19 L{middle dot}OVE repository at the time the systematic reviews conducted their own search. ResultsWe identified 83 eligible systematic reviews that included 2132 studies. COVID-19 L{middle dot}OVE had an overall comprehensiveness of 99.67% (2125/2132). The overall currency of the repository, that is, the proportion of articles that would have been obtained if the search of the reviews was conducted in COVID-19 L{middle dot}OVE instead of searching the original sources, was 96.48% (2057/2132). Both the comprehensiveness and the currency were 100% for randomised trials (82/82). ConclusionThe COVID-19 L{middle dot}OVE repository is highly comprehensive and current. Using this repository instead of traditional manual searches in multiple databases can save a great amount of work to people conducting systematic reviews and would improve the comprehensiveness and timeliness of evidence syntheses. This tool is particularly important for supporting living evidence synthesis processes
