Conscientiousness and temporal dynamics of blood pressure responses to repeated thermal pain stimuli: An exploratory mixed-effects analysis.

Autonomic pain responses show substantial inter-individual variability, yet the role of personality in their temporal dynamics remains poorly understood. This study examined, in an exploratory analysis, whether Big Five personality traits - and conscientiousness in particular - are associated with the trajectory of blood-pressure responses to repeated noxious thermal stimulation. Sixty-two healthy adults (33 men, 29 women; mean age 28.1 years, SD 6.7, range 19-40) underwent repeated thermal pain across four stimulation segments and three pain-related phases. Epoch-level mean blood pressure (MBP), derived from continuous non-invasive blood-pressure recording, was used as the physiological outcome, and ΔMBP was computed relative to the non-noxious Low phase. Linear mixed-effects models screened all five personality domains for an interaction with stimulus repetition (Segment), including stimulation phase and adjusting for age, sex, and subjective pain (ΔCoVAS); estimated marginal means were evaluated at representative conscientiousness levels (±1 SD). Of the five domains, only conscientiousness showed a nominally significant Segment × trait interaction (standardized β = 0.39 per SD; raw-score β = 0.018, p = .024). The segment trajectory was non-monotonic, and the conscientiousness-related difference was concentrated at one transition (S2→S3), where a steep decline at lower conscientiousness was markedly attenuated at higher conscientiousness. The linear interaction was attenuated when a by-subject random Segment slope was added, whereas the categorical interaction remained significant, indicating a non-linear, segment-specific pattern rather than robust linear moderation. Conscientiousness did not predict subjective pain (ΔCoVAS). Age was negatively associated with ΔMBP (p = .044) and, in sensitivity analyses, also moderated the segment trajectory. In this exploratory study, conscientiousness was associated with the temporal dynamics of pain-evoked blood-pressure responses - specifically a non-linear, segment-specific feature of the trajectory that was not paralleled by subjective pain. The findings highlight a potential role for personality in the temporal regulation of pain-related autonomic responses and require replication.