Effects of intermittent theta burst stimulation applied to the left dorsolateral prefrontal cortex on empathy and impulsivity in healthy adult males

Impulsivity and empathy are clinically relevant multi-dimensional concepts. Existing evidence suggests the left dorsolateral prefrontal cortex (LDLPFC) plays a crucial role in impulsivity and empathy. However, the neuromodulation effect of excitatory repetitive transcranial magnetic stimulation at the LDLPFC is insufficiently explored in the current literature. To address this important gap in the literature, we aimed to examine the effects of intermittent theta burst stimulation (iTBS) at the LDLPFC on impulsivity and empathy. A single-blind sham-controlled randomised crossover trial involving twenty-three healthy male adults was conducted. The iTBS protocol delivered 1800 pulses to the LDLPFC at 80% of the motor threshold in each condition. Trait impulsivity and empathy were measured at baseline using the Barrett Impulsiveness Scale and UPPS-P Impulsiveness Scale. The Reading the Mind in the Eyes Test, Information Sampling Task, and Adjusting Amount Task serving as behavioural measures of empathy, cognitive and temporal impulsivity respectively were administered before and after iTBS sessions. No significant changes were found on any of the measures after iTBS at the LDLPFC compared to the sham stimulation. Neuromodulation at the LDLPFC using iTBS may not alter cognitive empathy and temporal and cognitive impulsivity. Further research is required using amended protocols in a large-scaled sample.