Prefrontal EEG asymmetry as a potential biomarker of antidepressant treatment response with transcranial magnetic stimulation (TMS): a case series.

We review studies that have used EEG as a response biomarker in depression, and then present preliminary EEG change data from an ongoing TMS depression treatment trial. These data in 4 depressed subjects over 3 weeks of treatment suggest but do not prove that there may be asymmetry changes that occur both within a daily TMS session and over the course of several weeks that may be associated with antidepressant response. EEG shows potential as a biomarker of response for depression treatments, particularly the brain stimulation devices, which, unlike medications, can focally interact with neural tissue in specific frequency patterns.