The impact of melancholia versus non-melancholia on resting-state, EEG alpha asymmetry: electrophysiological evidence for depression heterogeneity.
While depression has been associated with relatively greater right than left frontal cortical activity - a neurophysiological marker reflecting greater activation of the withdrawal system - contradictory findings have been reported. It was hypothesised that melancholia would be associated with relative right frontal activation, in comparison to non-melancholia and controls. We collected 2-min of resting-state, eyes closed, electroencephalographic activity from a total of 237 participants including 117 patients with major depressive disorder (57 with melancholia, 60 with non-melancholia) and 120 healthy controls. In contrast to hypotheses, patients with non-melancholia displayed relative left frontal activation in comparison to controls and those with melancholia. These findings were associated with a small to moderate effect size (Cohen's d=0.30-0.34). Critically, patients with melancholic subtype did not differ from controls despite increased severity - relative to those with non-melancholia - on clinical measures. These results may reflect an increase in approach tendencies in patients with non-melancholia including reassurance seeking, anger or irritable aggression. Findings highlight the need for further research on the heterogeneity MDD.
Discipline of Psychiatry, Sydney Medical School, University of Sydney, Australia.
Candice R
CR
Quinn
School of Physics, University of Sydney, Sydney, New South Wales, Australia; Brain Dynamics Centre, University of Sydney, Westmead Hospital, Australia.
Chris J
CJ
Rennie
Discipline of Psychiatry, Sydney Medical School, University of Sydney, Australia; Brain Dynamics Centre, University of Sydney, Westmead Hospital, Australia.
Anthony W F
AW
Harris
Discipline of Psychiatry, Sydney Medical School, University of Sydney, Australia; University of Sydney Cognitive and Affective Neuroscience (SCAN) Research and Teaching Unit, School of Psychology, University of Sydney, Australia; University Hospital and Faculty of Medicine, University of São Paulo, São Paulo, Brazil. Electronic address: andrew.kemp@sydney.edu.au.
Andrew H
AH
Kemp
D000328:Adult; D002540:Cerebral Cortex / Q000503:physiopathology*; D003863:Depression / Q000175:diagnosis* / Q000503:physiopathology; D003866:Depressive Disorder / Q000175:diagnosis* / Q000503:physiopathology; D004569:Electroencephalography; D005260:Female; D005625:Frontal Lobe / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged
Alpha asymmetry; Depression; EEG; Electroencephalography; Melancholia; Non-melancholia