Associations between intraindividual reaction time variability, baseline respiratory sinus arrhythmia, and trait impulsivity in males with substance use disorders.

Trait impulsivity, characterized by the tendency to act without adequate consideration of potential consequences in pursuit of immediate rewards, is a recognized vulnerability marker for substance use disorders (SUDs). Cognitive control deficits are implicated in the manifestation of high trait impulsivity, and intraindividual reaction time variability (IIRTV), an indicator of cognitive control, may influence trait impulsivity. Baseline respiratory sinus arrhythmia (RSA) reflects vagal tone, serves as an index of physiological self-regulation, which has been demonstrated to be related to trait impulsivity. However, it is unclear whether IIRTV is associated with trait impulsivity and whether it interacts with baseline RSA to influence trait impulsivity. A total of 113 males with SUDs participated (Mage = 46.04 years, SD = 11.53) in this study. Trait impulsivity was assessed using a self-report questionnaire, IIRTV was measured through a two-choice oddball task, and baseline RSA was obtained through the collection of electrocardiogram (ECG) data. The results indicated that IIRTV interacted with baseline RSA to influence trait impulsivity. These findings suggested that cognitive control indexed by IIRTV, might represent a central nervous correlate of trait impulsivity, and that it interacted with vagal tone indexed by baseline RSA, to influence trait impulsivity.