Amygdala excitability to subliminally presented emotional faces distinguishes unipolar and bipolar depression: An fMRI and pattern classification study

• Published in: Human brain mapping Vol. 35; no. 7; pp. 2995 - 3007
• Main Authors: Grotegerd, Dominik, Stuhrmann, Anja, Kugel, Harald, Schmidt, Simone, Redlich, Ronny, Zwanzger, Peter, Rauch, Astrid Veronika, Heindel, Walter, Zwitserlood, Pienie, Arolt, Volker, Suslow, Thomas, Dannlowski, Udo
• Format: Journal Article
• Language: English
• Published: New York, NY Blackwell Publishing Ltd 01.07.2014; Wiley-Liss; John Wiley & Sons, Inc; John Wiley and Sons Inc
• Subjects: Adult; amygdala; Amygdala - blood supply; Amygdala - drug effects; Amygdala - physiopathology; Antidepressive Agents - therapeutic use; Biological and medical sciences; bipolar disorder; Bipolar Disorder - classification; Bipolar Disorder - diagnosis; Bipolar Disorder - drug therapy; Brain Mapping; depression; Depressive Disorder, Major - classification; Depressive Disorder, Major - diagnosis; Depressive Disorder, Major - drug therapy; Emotions - drug effects; Emotions - physiology; Face; Facial Expression; Female; fMRI; Fundamental and applied biological sciences. Psychology; Human; Humans; Image Processing, Computer-Assisted; Investigative techniques, diagnostic techniques (general aspects); Learning. Memory; Magnetic Resonance Imaging; Male; Medical sciences; Memory; Middle Aged; Nervous system; Oxygen - blood; pattern classification; Pattern Recognition, Visual - drug effects; Pattern Recognition, Visual - physiology; Photic Stimulation; Psychology. Psychoanalysis. Psychiatry; Psychology. Psychophysiology; Radiodiagnosis. Nmr imagery. Nmr spectrometry; Reaction Time - drug effects; Signal Detection, Psychological; subliminal emotion processing; Mood disorder; pattern classification; Nervous system diseases; Amygdala; Radiodiagnosis; subliminal emotion processing; Excitability; Bipolar disorder; Nuclear magnetic resonance imaging; fMRI; Unipolar; Classification; depression; Face; amygdala; bipolar disorder
• ISSN: 1065-9471; 1097-0193; 1097-0193
• DOI: 10.1002/hbm.22380

Background Bipolar disorder and Major depressive disorder are difficult to differentiate during depressive episodes, motivating research for differentiating neurobiological markers. Dysfunctional amygdala responsiveness during emotion processing has been implicated in both disorders, but the important rapid and automatic stages of emotion processing in the amygdala have so far never been investigated in bipolar patients. Methods fMRI data of 22 bipolar depressed patients (BD), 22 matched unipolar depressed patients (MDD), and 22 healthy controls (HC) were obtained during processing of subliminal sad, happy and neutral faces. Amygdala responsiveness was investigated using standard univariate analyses as well as pattern‐recognition techniques to differentiate the two clinical groups. Furthermore, medication effects on amygdala responsiveness were explored. Results All subjects were unaware of the emotional faces. Univariate analysis revealed a significant group × emotion interaction within the left amygdala. Amygdala responsiveness to sad>neutral faces was increased in MDD relative to BD. In contrast, responsiveness to happy>neutral faces showed the opposite pattern, with higher amygdala activity in BD than in MDD. Most of the activation patterns in both clinical groups differed significantly from activation patterns of HC—and therefore represent abnormalities. Furthermore, pattern classification on amygdala activation to sad>happy faces yielded almost 80% accuracy differentiating MDD and BD patients. Medication had no significant effect on these findings. Conclusions Distinct amygdala excitability during automatic stages of the processing of emotional faces may reflect differential pathophysiological processes in BD versus MDD depression, potentially representing diagnosis‐specific neural markers mostly unaffected by current psychotropic medication. Hum Brain Mapp 35:2995–3007, 2014. © 2013 Wiley Periodicals, Inc.