Cognitive appraisal modulates Theta Burst Stimulation effects on stress-reactive rumination and affect

The DLPFC plays a central role in cognitive appraisal and stress regulation, as this process-particularly secondary appraisal, where individuals assess their ability to cope with a situation-significantly influences stress responses on both psychological and physiological levels. We conducted a study where we applied different types of Theta Burst Stimulation (intermittent (i)TBS vs. continuous (c)TBS vs. sham (s)TBS) to the left DLPFC to increase or decrease the cortical excitability of the prefrontal neural network. We then examined how participants responded psychologically and physiologically to a potent psychosocial stressor, the Trier Social Stress Test (TSST), and aimed to investigate the influence of secondary cognitive appraisal on the effects of TBS on the stress response. Depending on the stimulation, we discovered that the cognitive appraisal significantly influenced rumination, positive and negative affect specifically in stress recovery. More precisely, as expected, individuals who perceived greater control experienced a faster recovery of stress-reactive ruminative thinking following sTBS and lower rumination following the stressor. We found lower increases and faster recovery of negative affect in all stimulation conditions and faster decreases in positive affect after the TSST following cTBS and iTBS, suggesting beneficial effects of both stimulation conditions. Concerning the assessed physiological variables, namely heart rate, heart rate variability, and salivary cortisol, we did not observe any impact of appraisal. These findings suggest that the effect of secondary appraisal on psychological variables depends on the type of stimulation, and while it may be linked to increased DLPFC activity, further research is needed to clarify the neurostimulation mechanisms involved.