The cognitive and neural basis of suicide : investigating factors that help to identify individuals at risk

Suicide is a public health problem and there is serious concern regarding the increase of suicidal acts. The main objective of this thesis was to investigate the relationship between different factors associated with suicide, specifically executive functioning, coping, and emotion regulation. These variables were investigated in accordance with suicide models that explain how different coping and emotion regulation strategies impact suicide, in particular, how cognitive reappraisal may act as a protective mechanism against suicidal behaviour. As the work was conducted in Hong Kong an initial study explored cross-cultural differences in suicidal behaviour and the links between self-reported executive function, coping, and suicide. It was found that greater use of avoidance coping and reduced use of reappraisal was associated with suicidality. The findings also showed that working memory, inhibition, and emotional control were important predictors for suicidality and this was explored further in an EEG study that measured frontal asymmetry in a series of cognitive tasks. It was postulated that lateralized brain activity may account for the executive function impairments in suicidal individuals as frontal asymmetry has been shown to relate to differential executive functioning. No differences in cognitive performance or asymmetry were found on the basis of reported suicide behaviour, however the sample generally reported low levels of suicide behaviour making any comparisons between high and low risk individuals difficult. A final experiment was completed to measure frontal asymmetry between individuals reporting low and more extreme levels of suicide behavior. Those reporting high levels of suicide behavior performed worse in a Stroop task revealing difficulties with inhibition, and they showed a specific attentional bias towards suicide-related stimuli in an emotional Stroop task. They also exhibited relatively less leftward frontal asymmetrical activity during the emotional Stroop task revealing difficulties in recruiting the left frontal region to deal with emotional interference. The findings suggest that an attentional bias towards suicide-related information may be an indicator of individuals with suicide risk. The current work also provides empirical evidence for suicidal models that predict that reappraisal helps protect against suicide whilst avoidance and information processing biases increase suicidality