Deficient interference inhibition for negative stimuli in depression: an event-related potential study.

OBJECTIVE: Depression is a commonly occurring mental disorder, and investigations have been carried out into attentional bias in this condition. The aim of the present study was to investigate the interference inhibition for emotional words in depressed individuals in the emotional Stroop task.
METHODS: Control participants, who had never suffered depression (NC), depressed patients, who were currently in remission (RMD) and participants diagnosed with a current major depressive disorder (MDD) were recruited using the Beck Depression Inventory (BDI), Beck Anxiety Inventory (BAI), Hamilton Rating Scale for Depression (HRSD) and Diagnostic and Statistical Manual for Mental Disorders (DSM)-IV as tools. Seventeen participants in each group completed an emotional Stroop task, and the event-related potential (ERP) was recorded during this cognitive task.
RESULTS: With regard to the behavioural data, MDD participants had higher interference effects for negative words compared with the other two groups and those of positive stimuli. With regard to the ERP data, the MDD participants showed a smaller N1 amplitude for negative words and a smaller P1 amplitude for positive words in bilateral hemispheres compared with the other groups. Both the MDD and RMD participants showed enhanced negativity (N450) over the parietal regions of the brain for negative words compared with NC groups.
CONCLUSIONS: MDD participants pay less attention to positive stimuli; they are characterised by deficient behavioural and neurophysiological indices of attentional inhibition for negative material. RMD participants are characterised by attentional inhibitory dysfunction of negative material only in terms of neurophysiological responses, a finding not entirely consistent with our previous study. SIGNIFICANCE: This is probably the first study to explore the cerebral mechanism of current and remitted depression using the emotional Stroop task. RMD participants were also examined to explore whether attentional bias of emotional stimuli was a stable cognitive vulnerability factor that might be associated with the recurrence of depression. This study and would shed light on the cognitive bias of depression for emotional stimuli.