An adaptive non-invasive alternating current brain stimulation system and method includes supplying transcranial alternating current stimulation (tACS) from a tACS source to a person, and receiving electroencephalogram (EEG) signals from EEG sensors disposed on the person, where the EEG signals including stimulation interference. The received EEG signals are processed using an adaptive model to estimate the stimulation interference in the EEG signals. The estimated stimulation interference is subtracted from the EEG signals to estimate neural oscillations of the person. The estimated neural oscillations are processed through an autoregressive model to generate predictions of future neural activity of the person and, based on the generated predictions, one or more electrical characteristics of the tACS being supplied to the person are varied to thereby modulate the neural oscillations of the person.