BDI-II scores were 6.0 ± 5.2 for older adults and 6.1 ± 5.1 for younger adults from Experiment 1, 6.0 ± 4.8 for older adults from Experiment 2, 5.8 ± 4.9 for younger adults from Experiment 3, and 6.1 ± 5.3 for younger adults from Experiment 4. Of note, the smoking status of subjects was not obtained in the present experiments. However, given emerging evidence suggesting that smoking may increase risk of cognitive decline in the elderly and non-elderly 49, and that nicotine deprivation may reduce cognitive functions and task-related neurophysiology 50, 51, it will be important for future studies to investigate the possibility of smoking status interactions with the effects of noninvasive neuromodulation and measures of neural synchronization used in the present study.
