0286 IS TRANSCRANIAL ALTERNATING CURRENT STIMULATION (TACS) AN EFFECTIVE TOOL TO ENTRAIN SPINDLES DURING SLEEP IN OLDER INDIVIDUALS?

• Published in: Sleep (New York, N.Y.) N.Y.), 2017-04, Vol.40 (suppl_1), p.A105-A105
• Main Authors: Bouchard, M, Fortin-Langelier, E, Frenette, S, Cyr, G, Latreille, C, Lina, J, Grossman, N, Carrier, J
• Format: Article
• Language: English
• Subjects: NREM sleep; Sleep
• ISSN: 0161-8105; 1550-9109
• DOI: 10.1093/sleepj/zsx050.285

Abstract Introduction: NREM sleep markers like sleep spindles are crucial for brain plasticity and their density, amplitude and duration decrease in aging. Few studies were able to entrain NREM sleep oscillations using transcranial alternating stimulation (TACS) and to enhance sleep-dependent memory consolidation. This pilot study aimed to induce sleep spindles using TACS in older individuals. Methods: Eighteen older (60-75yo; mean: 64yo) healthy participants came to the laboratory for polysomnographic recording of two counterbalanced naps with and without TACS (STIM and SHAM). Fourteen participants completed the study, as four participants were excluded because of insufficient sleep in at least one of the naps. In the STIM condition, one-sec bursts of TACS oscillating at 14Hz with a random delay between 4 and 10 sec., were applied bilaterally on central (C3, C4) locations for four minutes. Each stimulation periods were followed by two minutes without stimulation to allow the scoring of the EEG. Intensity of the stimulation was adjusted just below each individual sensation threshold (min.: 0,04mA; max.: 1mA). Parameters for the SHAM condition were exactly the same, except that TACS was turned on only one second at the beginning of the nap. The participants were blind to the conditions. After selecting EEG signals free of TACS artefacts, spindles were automatically detected on F3 and Cz. Differences in spindle characteristics between the two conditions (TACS, SHAM) were computed using paired T-tests. Results: In comparison with SHAM stimulation, TACS increased spindle density (p=0,053) in Cz derivation only. No significant effect was found for spindle duration, frequency and amplitude in Cz. No significant effect was observed in F3 derivation. Conclusion: TACS was able to locally enhance spindle density during a nap in a small sample of older participants. Whether this enhancement in sleep spindle density is linked to improved sleep-depend consolidation still needs to be evaluated. Support (If Any): This study was supported by the Canadian Institute of Health Research (CIHR) and the Natural Sciences and Engineering Research Council of Canada (NSERC).