Cortical mechanisms of the symptomatology in major depressive disorder: a resting EEG study.
BACKGROUND
Diagnosis and treatment rely on symptom criteria in modern psychiatry. However, the cortical mechanisms of symptomatology in major depressive disorder (MDD) are still not clear. This study examined neural correlates of symptom clusters of MDD by electroencephalography (EEG).


METHODS
Resting state eye-closed EEG signals were recorded in 196 depressive patients. Quantitative EEG (qEEG) of regional power, coherence and power series correlation across delta, theta, alpha and beta frequencies were used to correlate with overall depression severity evaluated by the Hamilton Depression Rating Scale (HDRS). Further, statistical comparisons between patients with high vs. low qEEG indices (median-split) were undertaken regarding symptom severity of core depression, sleep, activity, psychic anxiety, somatic anxiety, and delusion.


RESULTS
None of the qEEG indices significantly correlated with overall depression severity or differentiated symptom severity of core depression, sleep, activity and psychic anxiety. A higher symptom severity of somatic anxiety was associated with higher regional power over widespread cortical regions and lower strengths at bi-temporal, temporo-parietal and fronto-parietal connections. A higher symptom severity of delusion was associated with higher regional power in the frontal and temporal regions, and lower strengths at inter-hemispheric (frontal, temporal and parietal) and fronto-temporo-parietal connections.


CONCLUSIONS
Our EEG recording with sampling rate of 128Hz and 20 electrodes may provide restricted spatial and temporal precision.


CONCLUSIONS
Our results suggest that cortical mechanisms play important roles in the symptom manifestation of cognitive distortion (sub-score of delusion) and somatic anxiety in MDD. Our findings further imply that psychic anxiety and somatic anxiety are distinct entities.
Department of Psychiatry, Chang Gung Memorial Hospital, Taoyuan County, Taiwan.
Tien-Wen
TW
Lee
Younger W-Y
YW
Yu
Ming-Chao
MC
Chen
Tai-Jui
TJ
Chen
D000328:Adult; D000513:Alpha Rhythm / Q000502:physiology; D001611:Beta Rhythm / Q000502:physiology; D002540:Cerebral Cortex / Q000503:physiopathology*; D003700:Delta Rhythm / Q000502:physiology; D003865:Major Depressive Disorder / Q000503:physiopathology*; D004569:Electroencephalography; D005260:Female; D006801:Humans; D008297:Male; D011569:Psychiatric Status Rating Scales; D012720:Severity of Illness Index; D013826:Theta Rhythm / Q000502:physiology