0432 Neuromodulation of REM Sleep: Age-Associated Effects of Transcranial Magnetic Stimulation

Abstract Introduction We recently reported findings from a project that used a form of repetitive transcranial magnetic stimulation (rTMS) known as continuous theta burst stimulation (cTBS) to modulate connectivity within the brain’s Default Mode Network (DMN) as a potential treatment for insomnia. Continuous theta-burst stimulation(cTBS) was used to reduce cortical excitability within the DMN. Our prior analyses showed that the approach significantly improved total sleep time, sleep efficiency, N3 latency, and the arousal index, but rapid eye-movement (REM) did not appear affected. Based on growing evidence that REM sleep may show changes in the third decade and beyond, and that the effects of rTMS may be, at least partially, influenced by age, we further explored the potential effect of age in this dataset. Methods cTBS was administered to a total of 20 participants with self-reported insomnia symptoms (Mage=26.90, SD=6.56). Each participant underwent one round of sham stimulation and one round of active cTBS in a randomized order with one week in between. Participants were monitored with polysomnography (PSG) during a 7-hour sleep window. We first examined the association between age and REM sleep at each visit. A repeated measures ANOVA was employed, incorporating age as a covariate to assess potential age-dependent effects on cTBS effects. Results REM duration was positively correlated with age for the active cTBS visits (r=0.506, p=0.023) but not for the sham (r=-0.059, p= .806). With age as a covariate, the ANOVA revealed a significant effect of TMS treatment on REM sleep duration, F(1,18)=7.507, p=0.013. Participants in the TMS treatment group experienced an increase in REM sleep duration compared to the sham group when age was controlled in the analysis. Conclusion Age significantly influenced the effect of cTBS on REM sleep outcomes. The finding that older individuals demonstrated a greater effect of stimulation on REM duration suggests potential implications for clinical application in individuals with insomnia. Future work may focus on refining therapeutic strategies for sleep modulation, advocating for a personalized and age-aware approach. Support (if any) US Army Medical Research Acquisition Activity Grant: W81XWH2010173