These findings replicate, extend and formalize the previous finding (21) that depressed patients with prominent (large amplitude) EEG alpha benefit from treatment with an SRI. Patients who fail to respond to these antidepressants had markedly less alpha than responders and healthy controls. The present study was based on independent and considerably larger samples of depressed patients and healthy adults. Additionally, the EEG was recorded at a higher spatial resolution, and further enhanced by CSD measures, yielding reference-independent topographies that clearly implicate posterior anatomical regions in the generation of these condition-dependent alpha effects. A simple classification scheme, based on median alpha for healthy controls, yielded predictions of treatment outcome with a surprisingly high positive predictive value and specificity. There was no evidence to support a differential value for predicting response to SSRI monotherapy as opposed to dual therapy targeting both serotonergic and nonserotonergic neurotransmitters. These results are consistent with the view of alpha as a marker for SRI responsivity. In contrast to our previous findings (21), treatment response was not related to hemispheric asymmetry of posterior alpha. Although the reason for
