Volumetric differences in hippocampal subfields and associations with clinical measures in myalgic encephalomyelitis/chronic fatigue syndrome. — CFSMEATLAS
Volumetric differences in hippocampal subfields and associations with clinical measures in myalgic encephalomyelitis/chronic fatigue syndrome.
Thapaliya, Kiran, Staines, Donald, Marshall-Gradisnik, Sonya et al. · Journal of neuroscience research · 2022 · DOI
Quick Summary
Researchers used brain imaging to examine a part of the brain called the hippocampus, which is important for memory and thinking. They found that people with ME/CFS who met stricter diagnostic criteria had some structural differences in specific regions of their hippocampus compared to healthy people, and these differences were connected to how severe their fatigue and pain were. This finding supports the idea that ME/CFS involves real physical changes in the brain that may explain memory and cognitive problems patients experience.
Why It Matters
This study provides structural neuroimaging evidence that ME/CFS—particularly in strictly-defined cases—involves measurable brain changes in regions critical for memory and cognition. Understanding these physical changes may help validate ME/CFS as a neurobiological condition and eventually guide development of targeted treatments for cognitive and memory dysfunction.
Observed Findings
ME/CFS patients meeting ICC criteria showed significantly larger left subiculum head, left presubiculum head, and left fimbria volumes compared to healthy controls.
In ICC patients, increased fatigue severity was strongly associated with reduced left hippocampus tail volume.
In ICC patients, greater pain and lower physical function (SF36 scores) correlated with reduced volumes in the left GC-ML-DG head and CA4 head.
ME/CFS patients meeting only Fukuda criteria showed no significant hippocampal subfield volume differences from controls.
Structure-symptom correlations were substantially stronger in ICC-defined patients than Fukuda-defined patients.
Inferred Conclusions
Hippocampal subfield volumetric abnormalities are more prominent and clinically relevant in ME/CFS patients meeting stricter ICC diagnostic criteria than in Fukuda-criteria-only patients.
The hippocampus is structurally involved in ME/CFS pathophysiology and may contribute to observed cognitive and memory dysfunction.
Volumetric changes in specific hippocampal subregions correlate with symptom severity, particularly fatigue, pain, and physical functioning.
Remaining Questions
Do hippocampal volumetric changes precede ME/CFS symptom onset, develop during illness, or result from chronic symptoms?
What This Study Does Not Prove
This study cannot establish whether hippocampal volumetric changes cause ME/CFS symptoms or result from them—the association is correlational only. The cross-sectional design means we cannot determine if these brain changes develop over time or precede symptom onset. Results from only 18 ICC-criteria patients limit generalizability to all ME/CFS populations.
Why do volumetric differences appear more prominent in ICC-criteria versus Fukuda-criteria patients, and what does this suggest about ME/CFS heterogeneity?
Do these brain changes correlate with objective measures of cognitive impairment (e.g., neuropsychological testing) or only with patient-reported symptoms?
Are volumetric changes reversible with treatment, and do they progress over time?