P029 High-definition neurostimulation to enhance slow oscillations during sleep in obstructive sleep apnea: A randomised, single-blind, sham-controlled, crossover proof-of-concept protocol

Abstract Global and regional deficits in slow frequency EEG oscillations during non-rapid eye movement sleep, which have been reported in people with obstructive sleep apnea (OSA) may have detrimental consequences on cognitive performance. Current OSA treatments have variable effects on restoring slow waves and improving cognition, and some treatments are poorly tolerated. Previous studies using non-invasive transcranial direct current stimulation (tDCS) applied to frontal brain regions enhanced slow wave oscillations in healthy adults and may have utility in an OSA population. This protocol will assess the feasibility of using tDCS to enhance slow oscillations in middle to late aged people with OSA. A randomised, crossover design will test two active (maximum current density 0.522mA/cm2) and one sham (<0.1mA) slow oscillation tDCS conditions. In this proof-of-concept study, 5 participants aged 40-65 years with mild-moderate OSA will attend three in laboratory visits with high-density EEG, with a 1-week washout. Active or sham stimulation in frontal or parietal regions will be applied in 5 x 5-minute blocks during the first NREM period of a 90-minute nap. EEG data will be measured for 60 seconds after each stimulation block. Memory and attention tasks and a perception questionnaire will be completed before and after the nap. The primary outcome is technical feasibility. Secondary outcomes include protocol acceptability, blinding and perceived effectiveness and delta EEG power. Tertiary outcomes include visuo-spatial recognition, vigilance, sigma power, and sleep macro-architecture. Preliminary feasibility data on this novel intervention to target sleep and cognition in OSA will inform a larger clinical trial.