Using imipramine, Knott et al. (31) reported a trend for greater alpha, but significantly less theta, in treatment responders. For fluoxetine, Cook et al. (56) reported differences in theta band “cordance,” a measure related to the local Laplacian, but derived from a complex combination of relative and absolute power. Additional qEEG studies of treatment response have focused on midline frontal theta as identified by LORETA. Greater theta current density, localized by LORETA to the anterior cingulate cortex, has been reported for patients who respond to treatment with nortriptyline (33), citalopram or reboxetine (32). Korb et al. (34) also reported greater theta current density for responders than noresponders treated with fluoxetine or venlafaxine, but not between placebo responders and nonresponders. Given the secondary midline topography of our low-alpha/theta factor, midline findings might be anticipated,5 but differences between responders and nonresponders were not supported in analyses (Section S3 in the Supplement). Moreover, both low-alpha/theta and high-alpha were required to reliably differentiate between responders and nonresponders. Conventional EEG analysis did show a reduction in anterior-to-posterior gradient of condition-dependent theta power in nonresponders (Section
