The findings on the value of alpha as a predictor of treatment outcome are quite encouraging, but additional study is required with diverse treatments (e.g., nonserotonergic antidepressants, cognitive behavioral therapy or placebo) to determine whether the prediction uniquely reflects a serotonergic response. Using alpha levels in healthy controls as the threshold cutoff (cf. 21) proved again to be successful for predicting treatment response. Positive predictive value and specificity were very high (>90%), the clinical implication being that depressed patients having prominent alpha can be predicted to be responsive with a high degree of confidence. However, sensitivity was low (50%); about half of the responders had alpha below the control median, and were therefore not predicted to be responders. It is not known how many responders may have been placebo responders, shown spontaneous remission, or otherwise not been true drug responders. Further studies should explore other alpha thresholds, as well as combining alpha with other electrophysiologic (32, 54) or neurocognitive (55) measures to improve prediction of treatment response. Also, despite evidence that EEG alpha has high reliability and heritability (21–24), few
