10-Hz tACS counteracts PASAT-related suppression of alpha power: A pilot study

Although it is well known that the amplitude of electroencephalographic (EEG) alpha waves typically decreases during cognitive tasks, no studies have examined whether this attenuation can be modulated with external interventions. In this pilot study, we investigated whether transcranial alternating current stimulation (tACS) at a fixed frequency of 10 Hz could counteract task-related alpha suppression in 10 participants receiving experimental (verum) stimulation and 8 participants receiving sham stimulation. As expected, a mental task involving the Paced Auditory Serial Addition Test (PASAT) significantly reduced alpha power. However, after 10 min of 1 mA 10 Hz tACS, we observed a significant partial reversal of this attenuation (Group × Time: F(1,14) = 8.06, p = 0.013, η²p = 0.37), even as participants continued the task. In contrast, the sham control group showed no significant change. Consistently, PASAT behavioral accuracy improved after 10 Hz tACS (t(9) = 4.89, p = 0.0009, dz = 1.55), but not in the sham condition. In conclusion, these pilot findings demonstrate that 10 Hz tACS can counteract alpha power suppression and enhance cognitive performance during a demanding arithmetic task, warranting replication in larger and more diverse samples to confirm generalizability and clinical potential.