Mechanisms of Brain Aging and Their Links to Alzheimer’s and Parkinson’s Disease Pathology
Open Access
- 21 September 2026
- journal article
- review article
- Published by MDPI AG in International Journal of Molecular Sciences
- Vol. 27 (18) , 8426
Abstract
Brain aging is a major risk factor for neurodegenerative disorders and is associated with a progressive loss of neuronal homeostasis. Rather than resulting from a single pathological event, brain aging involves coordinated changes across multiple biological processes, including neuroinflammation, proteostasis impairment, mitochondrial dysfunction, neurotransmission deficit, cellular senescence, gut microbiota dysbiosis, extracellular vesicle dysregulation, nutrient-sensing disturbances, and metabolic drift. These processes interact across molecular, cellular, and systemic levels and may progressively increase neuronal vulnerability to neurodegenerative pathology. Age-related biological alterations may increase susceptibility to Alzheimer’s disease and Parkinson’s disease. Disease-associated proteins, including amyloid-β, tau, and α-synuclein, may interact with age-related inflammation, metabolic dysfunction, and loss of proteostasis. This review examines the evidence supporting these mechanisms, their interactions, and their relevance to normal brain aging, Alzheimer’s disease, and Parkinson’s disease. Because much of the current mechanistic evidence derives from animal and cellular models, further longitudinal and human studies are needed to provide a more complete understanding of how these mechanisms operate during human brain aging and neurodegenerative diseases.Keywords
Funding Information
- University Kebangsaan Malaysia Medical Centre (FF-2025-210)
This publication has 164 references indexed in Scilit:
- Role of Microglial Dysfunction in Parkinson’s Disease: From Multifactorial Causes to NeurodegenerationNeuroscience Bulletin, 2025
- Inhibition of tRF- 02514 in Extracellular Vesicles Preserves Microglia Pyroptosis and Protects Against Parkinson’s DiseaseMolecular Neurobiology, 2025
- Immune proteins C1q and CD47 may contribute to aberrant microglia-mediated synapse loss in the aging monkey brain that is associated with cognitive impairmentGeroScience, 2023
- Differential Regulation of Hippocampal IGF-1-Associated Signaling Proteins by Dietary Restriction in Aging MouseCellular and Molecular Neurobiology, 2016
- Abnormal serine phosphorylation of insulin receptor substrate 1 is associated with tau pathology in Alzheimer’s disease and tauopathiesActa Neuropathologica, 2014
- NADPH oxidase and aging drive microglial activation, oxidative stress, and dopaminergic neurodegeneration following systemic LPS administrationGlia, 2013
- Effect of dehydroepiandrosterone (DHEA) on monoamine oxidase activity, lipid peroxidation and lipofuscin accumulation in aging rat brain regionsBiogerontology, 2008
- Impairment of mitochondrial oxidative phosphorylation in the brain of aged miceBrain Research, 1994
- Oxidative damage to mitochondrial DNA shows marked age‐dependent increases in human brainAnnals of Neurology, 1993
- Altered dopamine receptor mediated signal transmission in the striatum of aged ratsBrain Research, 1993