Short Sleep Duration Associated with Low GABA Levels and Decreased Working Memory

by | Feb 22, 2024 | Brain Health, Gaba, Sleep

Written by Chrystal Moulton, Staff Writer. Lower GABA levels in the medial the prefrontal cortex and ACC were associated with poor performance in working memory [more errors on the CANTAB] (beta= – 0.21, P= 0.03).

woman sleepingLack of sleep is associated with an increased risk of structural and functional brain changes along with psychological and neurobiological deficits1-3. Previous studies have shown the areas most affected by short sleep duration is the anterior cingulate cortex [ACC] and medial prefrontal cortex4. Furthermore, studies have shown that GABA levels were significantly lower in the anterior singular cortex [ACC] in insomnia patients5. Thus, previous evidence indicates GABA plays an essential role in sleep maintenance and initiation6. In the current study7, researchers assessed levels of GABA and glutamate + glutathione levels in the anterior cingulate cortex [ACC] and medial prefrontal cortex in healthy individuals with subjective sleep issues.

Participants with no history of diagnosed sleep disorder, major psychiatric medical or neurobiological disorders; who were not taking sleep medicines nor presented with contraindications to MRI were included in this study. 166 individuals were eligible for the analysis (female: 82, male: 84). Participants were healthy individuals with complaints of difficulty falling asleep, not staying asleep, waking up too early in the morning, or waking up exhausted in the morning. None of the individuals included in this trial were diagnosed with insomnia. Each volunteer was given an actigraphy which they wore on their wrist for one night while sleeping. The actigraphy recorded sleep efficiency (total sleep time/total amount of time spent in bed), total sleep time, and wake time after sleep onset. Participants also completed a subjective sleep quality questionnaire [the Pittsburgh sleep quality index (PSQI)]. Following actigraphy data collected during one night of sleep, each volunteer underwent an MRI scan (specifically, magnetic resonance spectroscopy [MRS]) and a neuropsychological test [the computerized Cambridge Neuropsychological Test Automated Battery (CANTAB)] which tested spatial working memory. Total errors and strategy scores were calculated from the psychological test. MRI data was used to measure GABA and glutamate + glutathione levels in the medial prefrontal cortex and ACC. Participants were divided into two groups: shorter sleep duration group (< 6 hours of sleep the previous night) and longer sleep duration group (> 6 hours sleep the previous night). Researchers hypothesized that participants with shorter sleep duration group would have reduced levels of GABA and decreased working memory function.

Thirteen volunteers were excluded from this analysis due to lack of actigraphy and magnetic resonance spectroscopy data. A total of 153 participants were included in the analysis (longer sleep duration group, n = 79; shorter sleep duration group, n = 74). There’s a significant difference in sex proportion between the shorter versus longer sleep duration group (X2 = 7.11, P= 0.01). No significant differences were observed in the years of education and age between the two groups. Individuals in the shorter sleep duration group had lower sleep efficiency (t= 5.55, P< 0.001) and lower total sleep time compared to those in the longer sleep duration group (t= 14.7, P< 0.001). Self-reported habitual sleep duration and subjective sleep quality scores [PSQ I] were also significantly lower in the shorter sleep duration group (t= 3.21, P= 0.002 & t= – 3.04, P= 0.003, respectively). Self-reported habitual sleep duration correlated with actigraphy data (beta = 0.22, P< 0.001). No significant differences were observed in cerebral spinal fluid, grey matter, and white matter in the ACC and medial prefrontal cortex in either group. GABA levels, however, were significantly lower in the shorter sleep duration group, after controlling age, sex, and PSQI total score (t= -2.21, P= 0.03). No significant differences were observed in glutamate + glutathione levels (P= 0.84) after controlling for covariates [age, sex, and PSQI total score]. No significant difference was observed in working memory performance between the two groups (P= 0.48). However, researchers found that, in the shorter duration sleep group, lower GABA levels in the medial the prefrontal cortex and ACC were associated with poor performance in working memory [more errors on the CANTAB] (beta= – 0.21, P= 0.03) after controlling for covariates. No significant association between total errors and GABA levels were observed for those in the longer sleep duration. No significant association was observed in working memory strategy scores for both groups.

Overall, researchers demonstrated that individuals will shorter sleep duration represented with lower GABA levels in the anterior cingulate cortex and medial prefrontal cortex. Furthermore, lower GABA levels were associated with decreased spatial working memory function. This study supports results from previous trials suggesting the neurotransmitter GABA plays a critical role in sleep.

Source: Park, Shinwon, Ilhyang Kang, Richard AE Edden, Eun Namgung, Jinsol Kim, and Jungyoon Kim. “Shorter sleep duration is associated with lower GABA levels in the anterior cingulate cortex.” Sleep medicine 71 (2020): 1-7.

© 2020 Elsevier B.V. All rights reserved.

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Posted February 22, 2024.

Chrystal Moulton BA, PMP, is a 2008 graduate of the University of Illinois at Chicago. She graduated with a bachelor’s in psychology with a focus on premedical studies and is a licensed project manager. She currently resides in Indianapolis, IN.

References:

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