Alteration of intracerebral metabolites and subjective sleepiness by acute caffeine administration in adults

Qianqi Wang; Shanhua Li; Shuohua Wu; Huige Zhai; Yunmei Cui; Yumeng Mao; Gen Yan

doi:10.21037/qims-23-635

Alteration of intracerebral metabolites and subjective sleepiness by acute caffeine administration in adults

Quant Imaging Med Surg. 2023 Dec 1;13(12):7866-7878. doi: 10.21037/qims-23-635. Epub 2023 Sep 18.

Authors

Qianqi Wang^#^{1

2}, Shanhua Li^#¹, Shuohua Wu³, Huige Zhai⁴, Yunmei Cui⁵, Yumeng Mao³, Gen Yan²

Affiliations

¹ Department of Basic Medical Sciences, School of Medicine, Xiamen University, Xiamen, China.
² Department of Radiology, The Second Affiliated Hospital of Xiamen Medical College, Xiamen, China.
³ Department of Medical Imaging, The Second Affiliated Hospital, Medical College of Shantou University, Shantou, China.
⁴ Center of Morphological Experiment, Medical College of Yanbian University, Jilin, China.
⁵ Department of Pediatrics, Affiliated Hospital of Yanbian University, Jilin, China.

^# Contributed equally.

Abstract

Background: Caffeine is the most widely consumed psychostimulant. Despite this, the effects of acute caffeine intake on brain metabolite levels remain largely unknown. We aimed to investigate the effect of acute caffeine intake on brain metabolite concentrations in different caffeine consumption habit groups and to explore the association between metabolite changes and sleepiness.

Methods: Forty-five healthy adults were divided into groups based on their daily caffeine consumption: ≥1 cup/day, <1 cup/day, and no consumption. The exclusion criteria were the presence of neurological disorder, habitual consumption of mind-altering substances, and individuals who were unable to undergo magnetic resonance imaging. Mescher-Garwood point resolved spectroscopy and conventional spectroscopy data were acquired at 3 Tesla from voxels in the thalamus and posterior cingulate cortex (PCC). Subjective sleepiness was measured with the Karolinska Sleepiness Scale.

Results: The results of two-way repeated measures analysis of variance indicated a significant interaction effect between time and group for glutamate, glycerylphosphocholine and phosphocholine (GPC + PCH), myo-inositol, glutamate + glutamine (Glx), and creatine and phosphocreatine (Cr + PCr) of the thalamus (all P<0.01), and glutamate (P<0.0001), GPC + PCH (P=0.016), and Glx (P<0.0001) of the PCC. The change between pre- and post-caffeine intake results with significant reductions in γ-aminobutyric acid-positive macromolecule (GABA⁺) (thalamus, P=0.011), Glx (thalamus, P=0.002), glutamate (PCC, P<0.0001), and significant increments in GPC + PCH (thalamus, P=0.012 and PCC, P<0.0001), myo-inositol (thalamus, P=0.009), and Glx (PCC, P<0.0001). The change among the groups, with the ≥1 cup/day was significantly higher than the <1 cup/day or no consumption for glutamate (PCC, P=0.028), GPC (thalamus, P=0.001; PCC, P=0.026), and Cr + PCr (PCC, P=0.035); ≥1 cup/day was significantly lower than <1 cup/day and no consumption for glutamate (thalamus, P<0.0001), Cr + PCr (thalamus, P=0.003), Glx (thalamus, P=0.014), and myo-inositol (PCC, P=0.009). Bivariate correlation analysis revealed that GABA⁺ in the thalamus voxel (r=-0.7676; P<0.0001) was negatively correlated with subjective sleepiness.

Conclusions: Higher caffeine consumption had a significant impact on brain metabolites. Magnetic resonance spectroscopy was sensitive in measuring brain metabolite fluctuations after caffeine intake, particularly the levels of GABA⁺ in the thalamus, which was significantly correlated with sleepiness.

Keywords: Coffee; Mescher-Garwood point resolved spectroscopy (MEGA-PRESS); magnetic resonance spectroscopy (MRS); sleepiness; γ-aminobutyric acid (GABA).