Neurophysiologic predictors of treatment response to fluoxetine in major depression

Treatment with antidepressants is marked by heterogeneity of response; pred icting individual response to any given agent remains problematic. Neuroima ging studies suggest that response is accompanied by physiologic changes in cerebral energy utilization, but have not provided useful markers at pretr eatment baseline. Using quantitative EEG (QEEG) techniques, we investigated pretreatment neurophysiologic features to identify responders and non-resp onders to fluoxetine. In a double-masked study, 24 adult subjects with curr ent major depression of the unipolar type were studied over 8 weeks while r eceiving fluoxetine (20 mg QD) or placebo. Neurophysiology was assessed wit h QEEG cordance, a measure reflecting cerebral energy utilization. Response was determined with rating scales and clinical interview. Subjects were di vided into discordant and concordant groups based upon the number of electr odes exhibiting discordance. The concordant group had a more robust respons e than the discordant group, judged by lower final Hamilton Depression (HAM -D) mean score (8.0 +/- 7.5 vs. 19.6 +/- 4.7, P = 0.01) and final Beck Depr ession Inventory (BDI) mean score (14.0 +/- 9.4 vs. 27.8 +/- 3.7, P = 0.015 ), and by faster reduction in symptoms (HAM-D: 14.0 +/- 5.0 vs. 23.8 +/- 4. 1, P = 0.004 at 1 week). Groups did not differ on pretreatment clinical or historical features. Response to placebo was not predicted by this physiolo gic measure. We conclude that cordance distinguishes depressed adults who w ill respond to treatment with fluoxetine from those who will not. This meas ure detects a propensity to respond to fluoxetine and may indicate a more g eneral responsiveness to antidepressants. (C) 1999 Elsevier Science Ireland Ltd. All rights reserved.