A Multi-Dimensional Model of Fatigue in Old Age: Implications for Brain Aging

  • Feng V. Lin
    Send correspondence and reprint requests to Feng V. Lin, Ph.D., 1070 Arastradero road, Palo Alto, CA, 94304.
    Department of Psychiatry and Behavioral Sciences(FVL), Stanford University, Palo Alto, CA, 94304

    Wu Tsai Neuroscience Institute, Stanford University(FVL), Palo Alto, CA, 94304
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Published:November 04, 2022DOI:


      As the most reported symptom in old age, fatigue is understudied in terms of both mechanisms and measures. Population heterogeneity and methodological inconsistency makes understanding the relationship between fatigue and brain aging challenging. The present article comprehensively reviews existing conceptual and operational frameworks of fatigue, as well as mechanistic heterogeneities of fatigue that exist in the aging literature. Then, I propose a Multi-Dimensional Model of fatigue to provide theoretical cohesion to the study of fatigue in old age, along with a “fatigue circuit” addressing brain profiles across dimensions of fatigue. The potential relationships between fatigue dimensions, the fatigue circuit, and brain aging are discussed to inform the direction of future research.


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