- Concomitant medications during participation in a research study. No prescription or nonprescription medications with psychoactive properties that may affect EEG (such as over-the-counter dietary supplements, pseudoephedrine, or phenylpropanolamine). No antipsychotics, no psychostimulants, no antidepressants. Washout of at least one week or longer depending on the medication and clinician's judgment. Medication used for medical reasons must be cleared by research staff with consideration of known effects on EEG.