Heart rate variability could be related to cognitive but not motor inhibition in patients with temporomandibular disorders: an experimental study

Temporomandibular disorders (TMDs) are the most common cause of non-dental pain in the orofacial region; this condition involves changes in neural networks underpinning both pain processing and cognition that could impair executive functioning. Research shows scarce and controversial results in cognitive and motor inhibition abilities, a key component in pain management related to TMDs. Furthermore, heart rate variability (HRV) – an index of autonomic activity – appears to be impaired in several clinical conditions where cognition and self-regulation abilities are challenged, including TMDs. For this reason, this study aimed to investigate a potential relationship between alterations in HRV and performance on motor and cognitive inhibition tasks (respectively, Go-NoGo and Stroop tasks) in a sample of 14 patients with TMD and 15 healthy controls. In line with our hypothesis and previous literature, the group with TMD showed lower resting HRV, but no differences were found between groups in inhibition. Results showed significant positive correlations between HRV and Stroop Effect (on Reaction Times) in both groups, but only controls showed a positive correlation between resting vagal activity and both motor inhibition and congruent trials of the Stroop Task. Our results suggest that, despite a similar behavioral outcome, patients with TMD could have different activation patterns in neural areas responsible for movement planning and motor inhibition; in contrast, the ability to suppress dominant responses could rely on prefrontal activity strongly related to vagal influences on HRV. Further research focusing on TMDs is needed to improve knowledge about changes in neural functioning in this population.