ERP investigation of attentional disengagement from suicide-relevant information in patients with major depressive disorder

Background
Previous studies suggest the presence of attentional bias towards suicide-relevant information in suicidal individuals. However, the findings are limited by their reliance on behavioral measures. This study investigates the role of difficulty in disengaging attention from suicide-relevant stimuli using the P300 component of event-related potentials (ERPs).
Methods
Forty-four adults with Major Depressive Disorder (MDD) were administered the spatial cueing task using suicide-relevant and negatively-valenced words as cue stimuli. Disengagement difficulty was measured using reaction time and P300 during invalid trials.
Results
P300 amplitudes at Pz were higher in suicide-relevant compared to negatively-valenced word condition on invalid trials for participants with low rates of suicidal behavior. However, no such difference was found among participants with high rates of suicidal behavior. P300 amplitudes for suicide-relevant word condition were negatively correlated with “lifetime suicide ideation and attempt” at Pz. No significant results were found for the reaction time data, indicating that the ERP may be more sensitive in capturing the attentional disengagement effect.
Limitations
The groups were divided according to Suicidal Behaviors Questionnaire-Revised (SBQ-R) total score. Neutral stimulus was not included as cue stimuli. Most participants were under medication during the experiment.
Conclusions
Our results indicate that patients with MDD and low rates of suicidal behavior show difficulty in disengaging attention from suicide-relevant stimuli. We suggest that suicide-specific disengagement difficulties may be related to recentness of suicide attempt and that acquired capability for suicide may contribute to reduced disengagement difficulties.