The Association Between Suicidal Behavior, Attentional Control, and Frontal Asymmetry

Abstract

It can be difficult to identify those at risk of suicide because suicidal thoughts are often internalized and not shared with others. Yet to prevent suicide attempts it is crucial to identify suicidal thoughts and actions at an early stage. Past studies have suggested that deficits in attentional control are associated with suicide, with the argument that individuals are unable to inhibit negative thoughts and direct resources away from negative information. The current study aimed to investigate the association of suicidal behavior with neurological and behavioral markers, measuring attentional bias and inhibition in two Stroop tasks. Fifty-four participants responded to the color of color words in a standard Stroop task and the color of positive, negative, and neutral words in an emotional Stroop task. Electroencephalographic (EEG) activity was recorded from frontal areas during each task and at resting. Participants were separated into a low-risk and high-risk group according to their self-reported suicidal behavior. Participants in the high-risk group showed slower response times in the color Stroop and reduced accuracy to incongruent trials, but faster response times in the emotional Stroop task. Response times to the word "suicide" were significantly slower for the high-risk group. This indicates an attentional bias toward specific negative stimuli and difficulties inhibiting information for those with high levels of suicidal behavior. In the emotional Stroop task the high-risk group showed reduced activity in leftward frontal areas, suggesting limitations in the ability to regulate emotional processing via the left frontal regions. The findings support the argument that deficits in attentional control are related to suicidal behavior. The research also suggests that under certain conditions frontal asymmetry may be associated with suicidal behavior.

Keywords: attentional control; capability model; emotional Stroop; frontal asymmetry; inhibition; suicide.

Figure 1

Accuracy (total correct) and RT (ms) in the color Stroop task. Error bars represent standard error of the mean. (A) The interaction between suicidal behavior and congruency for accuracy. Reduced accuracy to incongruent trials compared with congruent trials was more apparent for the high-risk group. (B) Participants with a high risk of suicide were slower to identify the color of the words (regardless of congruency) than the low-risk group. Response times were also slower to incongruent trials compared with congruent.

Figure 2

Accuracy (total correct) and response times (ms) in the emotional Stroop task. Error bars represent standard error of the mean. There was a speed-accuracy trade-off in this task whereby the high-risk group responded faster (B) but were less accurate (A).

Figure 3

Measures of frontal alpha asymmetry (uV²) in the emotional Stroop task showing a more positive index for the low-risk group (a positive alpha asymmetry index reflects lower right frontal cortical activity and a negative asymmetry index reflects lower left frontal cortical activity). The asymmetry index was also higher for emotional trials compared with neutral. Error bars represent standard error of the mean.