Time-of-day study on brain metabolism using proton magnetic resonance spectroscopy
Clément Giraud1, Arnaud Poinas2, Landoline Bonnin3
1University Hospital center of Poitiers, Department of Imaging, France; Labcom I3M, Poitiers, University of Poitiers, France; Laboratoire de Mathématiques et Applications LMA, DACTIM-MIS team, CNRS UMR 7348, France.
Journal of Neuroradiology = Journal De Neuroradiologie
|October 20, 2025
Summary
Circadian rhythms minimally affect brain metabolism detectable by proton magnetic resonance spectroscopy (¹H-MRS). However, sex and brain hemisphere significantly influence metabolite levels, suggesting these factors are crucial for interpreting ¹H-MRS data.
Area of Science:
- Neuroscience
- Biochemistry
- Medical Imaging
Background:
- Circadian rhythms regulate physiological processes, including brain metabolism.
- Proton Magnetic Resonance Spectroscopy (¹H-MRS) quantifies brain metabolites.
- Previous studies show limited evidence of daily variations in brain metabolism.
Purpose of the Study:
- Investigate the time-of-day effect on brain metabolism using ¹H-MRS in healthy adults.
- Examine variations in specific brain regions associated with circadian rhythms.
- Assess the influence of sex and brain hemisphere on metabolite levels.
Main Methods:
- Prospective monocentric study with 39 healthy volunteers (25-40 years).
- Three 3T MRI sessions daily (7:30, 13:30, 17:30) with CSI ¹H-MRS sequences.
- Analysis of basal ganglia and semi-oval center metabolites (tCho, tNAA, Lac) using linear mixed models.
Main Results:
- Circadian rhythms showed minimal impact, except for a slight decrease in tCho/tNAA at 17:30.
- Significant differences observed between sexes: women had lower tCho/tCr and tCho/tNAA ratios than men.
- Brain hemisphere differences noted: right hemisphere showed higher tNAA/tCr and lower tCho/tNAA than the left.
Conclusions:
- ¹H-MRS metabolite ratios are largely unaffected by circadian rhythms in healthy adults.
- Patient sex and brain hemisphere significantly impact measured metabolite levels.
- Brain MRS examinations can be performed any time, but sex and hemisphere must be considered for accurate interpretation.
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