Objective: Given that lexical-semantic decline precedes episodic memory deficits in the Alzheimer's disease (AD) timeline, it is expected that performance on a lexical-semantic task would be associated with mediotemporal volumes independently of the association this region has with episodic memory in the early stage of AD.
Method: Fifty patients with mild cognitive impairment due to AD and 50 healthy adults completed tests of lexical-semantic skills (category fluency test), episodic memory for semantically relevant material (prose memory test), episodic memory for non semantically relevant material (Rey-Osterrieth Figure test), lexical-executive abilities (letter fluency test), and a neurostructural MRI. Hippocampal, perirhinal, entorhinal, temporopolar, and orbitofrontal volumes were extracted. The association between test performance and volume of each region was tested using partial correlations (age-education corrected). The improvement (ΔR2) in predicting volumetric indices offered by episodic-memory/lexical-semantic processing, once accounting for their counterpart, was tested using hierarchical regressions.
Results: There were no significant findings for control indices. Prose memory accounted for independent portions of volumetric variability within almost all regions. Category fluency accounted for independent portions of volumetric variability of left and right hippocampus and left perirhinal cortex in addition to the predictive strength of the Rey-Osterrieth Figure, and for an independent portion of volumetric variability in the left hippocampus in addition to the predictive strength of prose memory.
Conclusions: There was an association between hippocampal and perirhinal volume and lexical-semantic processing in addition to the contribution given by episodic memory. This statistical separation supports the importance of lexical-semantic processing as independent indicator of AD. (PsycINFO Database Record (c) 2019 APA, all rights reserved).
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http://dx.doi.org/10.1037/neu0000534 | DOI Listing |
Neural Comput
January 2025
Department of Psychological and Brain Sciences, Indiana University Bloomington, Bloomington, IN 47405, U.S.A.
How episodic memories are formed in the brain is a continuing puzzle for the neuroscience community. The brain areas that are critical for episodic learning (e.g.
View Article and Find Full Text PDFAlzheimers Dement
December 2024
Turner Institute for Brain and Mental Health & School of Psychological Sciences, Monash University, Clayton, VIC, Australia.
Background: Plasma and cerebrospinal (CSF) biomarkers are promising candidates for detecting neuropathology. While CSF biomarkers directly reflect pathophysiological processes within the central nervous system, their requirement for a lumbar puncture is a barrier to their widespread scalability in practice. Therefore, we examined cross-sectional associations of plasma biomarkers of amyloid (Aβ42/Aβ40 and pTau-181), neurodegeneration (Neurofilament Light, NfL), and neuroinflammation (Glial Fibrillary Acidic Protein, GFAP) with brain volume, cognition, and their corresponding CSF levels.
View Article and Find Full Text PDFAlzheimers Dement
December 2024
AdventHealth Research Institute, Neuroscience, Orlando, FL, USA.
Background: Aging is associated with heightened systemic inflammation, decline in selective aspects of cognition, and an increase in white matter lesions (WMLs). Both WMLs and systemic inflammation have been related to cognition. However, it is not clear how they interdependently relate to cognitive aging.
View Article and Find Full Text PDFAlzheimers Dement
December 2024
Department of Neurobiology, Care Sciences and Society, Center for Alzheimer Research, Division of Clinical Geriatrics, Karolinska Institutet, Stockholm, Sweden.
Background: [F]FDG PET is essential since it allows us to differentiate between different dementia disorders/types, revealing distinct neurodegenerative patterns in those predisposed to the condition. Individuals with Autosomal Dominant Alzheimer's Disease (ADAD) have a predictable age of onset, enabling the study of cognitive and pathological changes before clinical manifestation. Our objective was to investigate temporal course and regional links between cognition and glucose metabolism as a measure of early synaptic impairment in ADAD.
View Article and Find Full Text PDFBackground: Tau pathology accumulates early in the basal forebrain (BF) in Alzheimer's disease (AD). The feasibility of measuring in vivo BF tau is unclear given PET resolution and possible partial volume effects of off-target signal (OTS) which varies by tracer.
Method: We compared measurements of tau in cognitively unimpaired older adults with either an FTP or MK6240 scan: 93 FTP scans from the Berkeley Aging Cohort Study (BACS), 424 FTP scans from ADNI (N=517 FTP scans; 72.
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