Stress and Aggression – The influence of stress on processing of provoking stimuli during a retaliation paradigm- an ERP study

Many studies suggest a vicious circle between stress and aggression. But its physiological basis is not fully understood. Trait aggression and externalizing behavior are characterized by reduced P3 waves in Event Related Potentials (ERP). Stress affects the processing of aggression related stimuli. Moreover, the stress hormone cortisol enhances the attention to social threat and the propensity for aggression. The aim of the present study was to asses the effect of acute stress and the concomitant cortisol release on the processing of provoking stimuli during an aggressive encounter using the Taylor Aggression Paradigm (TAP). 71 healthy participants (36 men) were subjected to the socially evaluated cold pressor test as an experimental stressor or to a warm pressor test (control condition). Half of each group received high or low levels of provocation in the TAP. Throughout the experiment EEG was recorded, and salivary cortisol was collected. Stressed participants were divided into cortisol-responders and –non responders. Event-related potentials during provoking stimuli revealed that highly provoked participants had a more positive P3 amplitude (fronto-central) compared to hardly provoked participants, replicating previous findings. Increased cortisol combined with provocation led to a reduced P3 amplitude and reduced late positive potentials in cortisol-responders. The results suggest that an interaction between stressor-induced cortisol and provocation affects the processing of conflict signals and contributes to a vicious cycle between stress and aggression.