Previous studies of patients with unipolar depression have shown that early decreases of prefrontal quantitative EEG (QEEG) cordance in theta band can predict clinical response to various antidepressants. We now examined whether reduction of prefrontal cordance value after 1 week of venlafaxine treatment predicts clinical response to venlafaxine in non-responders to previous antidepressant treatments.

We analyzed 25 inpatients, who finished 4-week treatment with venlafaxine. EEG data were monitored at baseline and after 1 week of treatment. QEEG cordance was computed at 3 frontal electrodes in theta frequency band. Depressive symptoms were assessed using Montgomery-Åsberg Depression Rating Scale (MADRS).

Eleven of 12 responders (reduction of MADRS ≥50%) and only 5 of 13 non-responders decreased prefrontal QEEG cordance value after the first week of treatment. The decrease of prefrontal cordance after week 1 in responders was significant (p=0.03) and there was no change in nonresponders. Positive and negative predictive value of cordance reduction for response was 0.7 and 0.9, respectively.

The reduction of prefrontal theta QEEG cordance value after first week of treatment is a useful tool in the response prediction to venlafaxine.

This study was supported by a grant from Internal Grant Agency of Ministry of Health of Czech Republic No. NR/9330-3 and a grant of Ministry of Education of Czech Republic MSMT 1M0517.