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| Bill Yates Brain Posts |
Clinicians and individuals with depression understand the tendency for depression to be associated with over-interpretation of negative cues in the environment. Depression seems to heighten perception of negative environmental cues including interpersonal (or social) cues. The cognitive behavioral model of depression emphasizes the cognitive triad—a negative bias (view) of the self, the environment and the future.Functional magnetic resonance imaging is providing a model to study emotional processing and better understand how this processing may be disturbed in depression. When shown brief images of emotion-laden faces, subjects suffering from depression show exaggerated responses. Depressed or angry faces produce heighted amygdala responses in those with depression. Happy faces produce a blunted amygdala response.
Teresa Victor and colleagues recently published a study in the American Journal of Psychiatry providing additional information about this emotional processing bias. (Disclosure:Dr. Victor is now a neuroscientist with the Laureate Brain Institute-my employer). She summarized her findings in a recent journal club.Here are the key findings from her recent research:
- The amygdala response to facial images occurs even with brief subliminal (unconscious) presentations
- Sad facial images activate the amygdala in depressed subjects (compared to controls) in both those with active and remitted depression
- Happy facial images activate the amygdala in controls more than depressed subjects
- Eight weeks of selective serotonin reuptake inhibitor therapy (sertraline) reverse(normalize) the amygdala response to facial emotion cues
The authors summarize their findings “These data demonstrate that negative emotional-processing biases occur automatically, below the level of conscious awareness, in unmedicated, currently depressed people…”. “This nonconscious processing of emotional stimuli is consistent with evidence that the amygdala contains cells that are tuned selectively to specific stimulus characteristics, facilitating early detection of biologically salient information”.
The findings from this research suggest exaggerated amygdala responses to sad faces may be a trait marker and not just due to the presence of active depression. This might allow this trait to be studied as an endophenotype (or potential genetic marker for depression). Normalization of this exaggerated response with selective serotoning reuptake inhibitors may provide an additional paradigm for studying the effect of new novel antidepressants.
From the clinical standpoint, this study suggests that negative emotional cues may occur below the level of consciousness in the daily lives of those with depression. It supports clinical experience that some dysphoria may occur in response to environmental cues patients do not remember (or recognize at the time of the cue). Further study of emotional processing is likely to advance both the research and clinical understanding of depression and other mood disorders.
Photo of sea gull over beach at Jupiter Island, Florida courtesy of Yates Photography.
Victor TA, Furey ML, Fromm SJ, Ohman A, & Drevets WC (2010). Relationship between amygdala responses to masked faces and mood state and treatment in major depressive disorder. Archives of general psychiatry, 67 (11), 1128-38 PMID: 21041614.
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