Volumetric differences in hippocampal subfields and associations with clinical measures in myalgic encephalomyelitis/chronic fatigue syndrome, by Kiran Thapaliya, Donald Staines, Sonya Marshall- Gradisnik, Jiasheng Su, Leighton Barnden in Journal of Neuroscience Research March 31, 2022
“The hippocampus is a small, curved formation in the brain that plays an important role in the limbic system. The hippocampus is involved in the formation of new memories and is also associated with learning and emotions.” 1
Research abstract:
Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) patients suffer from a cognitive and memory dysfunction. Because the hippocampus plays a key role in both cognition and memory, we tested for volumetric differences in the subfields of the hippocampus in ME/CFS.
We estimated hippocampal subfield volumes for 25 ME/CFS patients who met Fukuda criteria only (ME/CFS Fukuda), 18 ME/CFS patients who met the stricter ICC criteria (ME/CFS ICC), and 25 healthy controls (HC).
Group comparisons with HC detected extensive differences in subfield volumes in ME/CFS ICC but not in ME/CFS Fukuda. ME/CFS ICC patients had significantly larger volume in the left subiculum head (p<0.001), left presubiculum head (p=0.0020), and left fimbria (p=0.004).
Correlations of hippocampus subfield volumes with clinical measures were stronger in ME/CFS ICC than in ME/CFS Fukuda patients. In ME/CFS Fukuda patients, we detected positive correlations between fatigue and hippocampus subfield volumes and a negative correlation between sleep disturbance score and the right CA1 body volume. In ME/CFS ICC patients, we detected a strong negative relationship between fatigue and left hippocampus tail volume.
Strong negative relationships were also detected between pain and SF36 physical scores and two hippocampal subfield volumes (left: GC-ML-DG head and CA4 head). Our study demonstrated that volumetric differences in hippocampal subfields have strong statistical inference for patients meeting the ME/CFS ICC case definition and confirms hippocampal involvement in the cognitive and memory problems of ME/CFS ICC patients.
Research significance:
Our study found left hippocampal subiculum, presubiculum, and fimbria volumes were significantly larger in ME/CFSICC patients compared with Health Controls, but not for ME/CFSFukuda patients.
Furthermore, this study demonstrated that multiple hippocampal subfield volumes are different in ME/CFSICC patients meeting the strict ICC case definition, and they exhibited strong associations with clinical measures.
Therefore, the strict case definitions are essential in investigation of the pathophysiology of ME/CFS. Subiculum and parasubiculum volumes were larger in ME/CFS in contrast to reductions seen in other neurological disorders.
