Author(s): SCHERRER, S., EGGER, S., WICK, A., LIU, X., XIN, L., RASCH, B., LAUBER, B., TAUBE, W., Institution: UNIVERSITY OF FRIBOURG, Country: SWITZERLAND, Abstract-ID: 2333

INTRODUCTION:
Around 50% of individuals aged 60 and older experience sleep problems, and current insomnia treatments are difficult to access or have adverse effects [1]. Thus, there is urgent need for alternatives. Gamma-aminobutyric acid (GABA)-mediated inhibition is crucial for sleep [2] and older adults exhibit lower GABA levels [3]. Interestingly, balance training has been shown to enhance GABA-mediated inhibition [4]. Thus, we hypothesised that balance training would improve sleep quality in older adults.
METHODS:
60 volunteers (64-81 years old) were randomly assigned to a three-month balance intervention (> 30 sessions; BT), a three-month strength intervention (> 30 sessions; ST) or a control group, following their daily routines (CON). Before and after the three-month period, subjective sleep quality was evaluated with the Pittsburgh Sleep Quality Questionnaire (PSQI). Sleep efficiency was recorded with polysomnography (PSG) at the participant’s home. During an afternoon nap in the laboratory, short- interval intracortical inhibition (SICI), a measure of the activity of GABAergic inhibitory interneurons in the motor cortex, was assessed. GABA and lactate levels in the motor cortex were determined with magnetic resonance spectroscopy. Linear mixed-effects models (LME), followed by Bonferroni-corrected paired t- tests and cohen’s d effect sizes with 95% confidence intervals were calculated.
RESULTS:
LME indicated a significant time effect for PSQI scores (p=.016). BT improved subjective sleep quality by -1.35 score points (d=0.58, 95% CI [0.06, 1.09], p=.046), with no change in ST (p=1) and CON (p=1). Improved sleep scores in BT showed a trend towards a strong correlation with increased SICI at sleep onset (r =-0.59, p=.073). Furthermore, a time effect on GABA levels was revealed (p=.025). BT increased GABA levels by 22% (d=0.97, 95% CI [0.40, 1.55], p=.009), while ST (p=1) and CON (p=1) showed no change. Sleep efficiency demonstrated a significant interaction effect of group and time (p=.006): BT (p=.353) and CON (p=1) did not change significantly while ST increased sleep efficiency by 7% (d=0.71, 95% CI [0.22, 1.21], p=.022). Additionally, ST revealed a significant decrease in brain lactate level (p=.02).
CONCLUSION:
Older adults showed improved subjective sleep quality along with increased GABA levels after BT. Moreover, increased GABAergic inhibition at sleep onset was associated with improved sleep scores. These findings support the idea that BT counteracts hyperarousal in the elderly brain [5]. The observed decrease in brain lactate, a biomarker of sleep [6], suggests that ST improves sleep efficiency by improving lactate metabolism, as previously shown in animal models [7].
1. Patel, D. et al., J Clin Sleep Med, 2018.
2. Saper, C.B. et al., Nature, 2005.
3. Cuypers, K. et al., Aging (Albany NY), 2018.
4. Taube, W. et al., Eur J Neurosc, 2020.
5. Riemann, D. et al., Sleep Med Rev, 2010.
6. Naylor, E. et al., Sleep, 2012.
7. Carroll, C.M. et al., bioRxiv, 2022.