10. 10. 2010
A considerable body of research supports the assertion that antidepressant medication effects are physiologically detectable in the EEG. QEEG cordance is a new quantitative EEG measure that combines complementary information from absolute and relative power of EEG spectra. Previous studies of patients with unipolar depression have shown that decreases in prefrontal theta band (4-8 Hz) cordance 1 week after start of antidepressant medication have predicted clinical response with overall accuracy ranging from 72% to 88%. The aim of this study was to evaluate the efficacy of QEEG cordance in the prediction of response to various antidepressants in patients with resistant depression.
A total of 81 inpatients (52 females) with depressive disorder (Montgomery-Åsberg Depression Rating Scale; MADRS≥20) who previously did not respond to at least one antidepressant treatment were treated with various antidepressants for 4 weeks. EEG data were monitored at baseline and after one week. QEEG cordance was computed at 3 frontal electrodes (Fp1, Fp2, Fz) in theta frequency band (4-8 Hz). Depressive symptoms were assessed using MADRS and response to treatment was defined as a ≥50% reduction of MADRS score.
There were no baseline differences in demographic and clinical parameters between responders and nonresponders. 29 from 33 responders and 14 from 48 non-responders decreased prefrontal QEEG cordance value after the first week of treatment (Χ2, p=0.0001). There was a difference between responders and nonresponders in the change of cordance value after 1 week of treatment (p=0.002). Positive and negative predictive value of cordance reduction for response to treatment was 0.67 (95% CI, 0.58-0.73) and 0.90 (95%CI, 0.79-0.96), respectively. The overall accuracy of the test was 0.78 (95% CI, 0.68-0.83) and the effect size estimated from this sample (w = 0.59) was in large range.
Early change in prefrontal theta band cordance probably reflects a common underlying mechanism of antidepressant effect, regardless of the type of treatment. Prefrontal cordance may provide a useful biomarker for the early detection of response to antidepressant therapy.
This study was supported by projects of The Ministry of Education, Youth and Sports of the Czech Republic No.1M0517 and MSM0021620816.