Sleep Med Psychophysiol.  2021 Jun;28(1):18-26. 10.14401/KASMED.2021.28.1.18.

Brain Metabolite Changes in Insomnia and Obstructive Sleep Apnea

• Hong H
• Lee H
• Yoon S
• Kim J

• KMID: 2518340
• DOI: http://doi.org/10.14401/KASMED.2021.28.1.18

Abstract

Sleep is essential to brain function and mental health. Insomnia and obstructive sleep apnea (OSA) are the two most common sleep disorders, and are major public health concerns. Proton magnetic resonance spectroscopy (¹H-MRS) is a non-invasive method of quantifying neurometabolite concentrations. Therefore, ¹H-MRS studies on individuals with sleep disorders may enhance our understanding of the pathophysiology of these disorders. In this article, we reviewed ¹H-MRS studies in insomnia and OSA that reported changes in neurometabolite concentrations. Previous studies have consistently reported insomnia-related reductions in γ-aminobutyric acid (GABA) levels in the frontal and occipital regions, which suggest that changes in GABA are important to the etiology of insomnia. These results may support the hyperarousal theory that insomnia is associated with increased cognitive and physiological arousal. In addition, the severity of insomnia was associated with low glutamate and glutamine levels. Previous studies of OSA have consistently reported reduced N-acetylaspartate (NAA) levels in the frontal, parietooccipital, and temporal regions. In addition, OSA was associated with increased myo-inositol levels. These results may provide evidence that intermittent hypoxia induced by OSA may result in neuronal damage in the brain, which can be related to neurocognitive dysfunction in patients with OSA. The current review summarizes findings related to neurochemical changes in insomnia and OSA. Future well-designed studies using ¹H-MRS have the potential to enhance our understanding of the pathophysiology of sleep disorders including insomnia and OSA.

Keyword

GABA; Insomnia; NAA; Obstructive sleep apnea; ¹H-MRS; Neurometabolite