Background
Attentional biases, particularly difficulty inhibiting attention to negative stimuli, are implicated in risk for major depressive disorder (MDD). The current study examined a neural measure of attentional bias using a continuous index of visuocortical engagement (steady-state visual evoked potentials [SSVEPs]) before and after a negative mood induction in a population at high-risk for MDD recurrence due to a recently remitted MDD (rMDD) episode. Additionally, we examined working memory (WM) capacity as a potential moderator of the link between rMDD and visuocortical responses.
Methods
Our sample consisted of 27 women with rMDD and 28 never-depressed women. To assess attentional inhibition to emotional stimuli, we measured frequency-tagged SSVEPs evoked from spatially superimposed task-relevant stimuli and emotional distractors (facial displays of emotion) oscillating at distinct frequencies. WM capacity was assessed during a visuospatial memory task.
Results
Women with rMDD, relative to never-depressed women, displayed difficulty inhibiting attention to all emotional distractors before a negative mood induction, with the strongest effect for negative distractors (sad faces). Following the mood induction, rMDD women’s attention to emotional distractors remained largely unchanged. Among women with rMDD, lower WM capacity predicted greater difficulty inhibiting attention to negative and neutral distractors.
Conclusions
By exploiting the phenomenon of oscillatory resonance in the visual cortex, we tracked competition in neural responses for spatially superimposed stimuli differing in valence. Results demonstrated that women with rMDD display impaired attentional inhibition of emotional distractors independent of state mood and that this bias is strongest among those with lower WM capacity.
