Revised: February 25, 2013
Accepted: March 15, 2013
Published online: June 22, 2013
Processing time: 286 Days and 4.4 Hours
AIM: To investigate neural and behavioral correlates of emotional experiences as potential vulnerability markers in remitted depression.
METHODS: Fourteen remitted participants with a history of major depression and fourteen closely matched healthy control participants took part in the study. We used two psychiatric interviews (Hamilton Depression Rating Scale, Montgomery-Asberg Depression Rating Scale) and one self-report scale (Beck Depression Inventory) to assess remission. Healthy control participants were interviewed by an experienced psychiatrist to exclude those who showed any current or lifetime psychiatric or neurological disorders. To explore psychosocial and cognitive-interpersonal underpinnings of potential vulnerability markers of depression, early life stress, coping styles and alexithymia were also assessed. We induced pleasant and unpleasant emotional states using congruent combinations of music and human emotional faces to investigate neural and behavioral correlates of emotional experiences; neutral stimuli were used as a control condition. Brain responses were recorded using functional magnetic resonance imaging. Behavioral responses of pleasantness, arousal, joy and fear were measured via button-press inside the resonance imaging scanner.
RESULTS: The mean age of the sample was 54.9 (± 11.3) years. There were no differences between remitted depressed (RD) (n = 14; 9 females and 5 males) and healthy participants (n = 14; 8 females and 6 males) regarding age, current degree of depression, early life stress, coping styles and alexithymia. On a neural level, RD participants showed reduced activations in the pregenual anterior cingulate cortex (pgACC) in response to pleasant [parameter estimates: -0.78 vs 0.32; t(26) = -3.41, P < 0.05] and unpleasant [parameter estimates: -0.88 vs 0.56; t(26)= -4.02, P < 0.05] emotional stimuli. Linear regression analysis revealed that pgACC activity was modulated by early life stress [β = -0.48; R2 = 0.23, F(1,27) = 7.83, P < 0.01] and task-oriented coping style [β = 0.63; R2 = 0.37, F(1,27) = 16.91, P < 0.001]. Trait anxiety modulated hippocampal responses to unpleasant stimuli [β = 0.62; R2 = 0.38, F(1,27) = 15.95, P < 0.001]. Interestingly, in their reported experiences of pleasantness, arousal, happiness and fear in response to pleasant, unpleasant and neutral stimuli, RD participants did not differ significantly from healthy control participants. Adding trait anxiety or alexithymia as a covariate did not change the results.
CONCLUSION: The present study indicates that, in euthymic individuals, depression history alters neural correlates, but not the subjective dimension of pleasant and unpleasant emotional experiences.
Core tip: A profound disturbance of emotional experiences is one of the key symptoms of major depressive disorder. Therefore, we investigated alterations in neural correlates of emotional experiences in individuals at risk for major depression to identify potential vulnerability markers for depression. Pleasant and unpleasant emotional states were induced via music and emotional faces while recording brain responses via functional magnetic resonance imaging. Our study shows that pregenual anterior cingulate cortex reactivity in response to emotional stimuli can serve as a “neural marker” for depression vulnerability - a finding that, if replicated, could be important for innovations in early diagnosis or therapy.