Regional gray matter volume correlates to physical and mental fatigue in healthy middle-aged adults.
Putra, Handityo Aulia, Park, Kaechang, Yamashita, Fumio et al. · Neuroimage. Reports · 2022 · DOI
Quick Summary
Researchers used brain scans to examine whether the size of certain brain regions relates to how tired people feel, both physically and mentally. In a large group of nearly 1,900 healthy middle-aged adults, they found that specific brain areas showed different sizes depending on fatigue levels—some areas were smaller in people reporting more fatigue, while others were larger. This suggests that brain structure may be connected to how tired we feel, even before someone develops a condition like ME/CFS.
Why It Matters
Understanding brain structural changes associated with fatigue in healthy populations may illuminate early mechanisms of fatigue development and provide insights into how ME/CFS-related fatigue could originate. Identifying consistent brain regions involved in fatigue (such as the right SMC) could eventually lead to biomarkers for early detection and prevention strategies. This research bridges healthy fatigue physiology and pathological fatigue conditions, relevant for understanding disease progression.
Observed Findings
Right supplemental motor cortex volume negatively correlated with physical, mental, and total fatigue scores (smaller volume = higher fatigue).
Left putamen and middle temporal gyrus volumes positively correlated with physical and total fatigue (larger volume = higher fatigue).
Right planum temporale volume negatively correlated with physical fatigue only.
Left lateral orbital gyrus volume negatively correlated with mental fatigue only.
Left fusiform gyrus volume positively correlated with mental fatigue only.
Inferred Conclusions
The right supplemental motor cortex may play a critical role in fatigue development, as it was the only brain region consistently associated across all fatigue measures.
The left putamen may serve a compensatory function in response to fatigue, showing positive correlation with physical and total fatigue scores.
Multiple distributed brain regions are involved in fatigue perception, suggesting fatigue involves complex neural networks rather than single structures.
Structural brain variations in healthy individuals may predispose to or reflect early-stage fatigue progression, offering potential prevention targets.
Remaining Questions
Does brain volume change precede fatigue development, or does experiencing fatigue cause structural changes? Longitudinal studies are needed to establish temporal relationships.
What This Study Does Not Prove
This study does not prove that brain volume changes *cause* fatigue—it only shows correlation, and causation could work in reverse or involve confounding factors. The findings in healthy adults may not directly translate to ME/CFS pathophysiology, as chronic disease involves distinct pathological processes. The study cannot establish whether these brain differences emerge before fatigue develops or result from experiencing fatigue.