Regular Cannabis Use Impairs Autonomic Cardiovascular Control in Humans

Introduction: Regular cannabis use is associated with an increased risk of adverse cardiovascular outcomes such as arrhythmias, myocardial infarction, and stroke. Multiple physiological mechanisms could underlie the elevated cardiac risk in individuals who regularly use cannabis, such as deleterious effects on platelet and endothelial function. However, it is unclear whether regular cannabis use impairs autonomic cardiac control, which is also a risk factor for adverse cardiovascular events. The cardiovagal baroreflex is critical for maintaining arterial pressure homeostasis and is an index of vagal modulation of the heart. Therefore, we hypothesized that regular cannabis users would have attenuated baroreflex sensitivity and heart rate variability (HRV) at rest compared to individuals who do not use cannabis. Methods: 24 individuals who regularly use cannabis (Cannabis; 12 female, 27±4 years old, Cannabis Use Disorder Identification Test score 16±7 (CUDIT-R; scores ≥8 indicate hazardous cannabis use) and BMI 24±5 kg·m -2 ) and 13 individuals with no cannabis use (Control; 7 female, age 26±4 years, and BMI 23±3 kg·m -2 ).Cannabis use was permitted ad libitum at home leading up to the laboratory visit and measures were assessed in the evening ~4 hours before habitual sleep time. Participants were supine and paced their breathing to a metronome set to 0.25 Hz for 10 minutes. We recorded the ECG, and beat-to-beat arterial pressure (finger plethysmography). Cardiovagal baroreflex sensitivity (cvBRS) was determined by sequences of three or more concurrent beat-to-beat changes in the R-R interval (RRI) and systolic pressure (SAP) using both cvBRS-up (SAP increase & RRI lengthen; vagal activation) and cvBRS-down (SAP decrease & RRI shorten; vagal inhibition) sequences. Only sequences with linear r-values >0.7 were accepted. HRV was assessed in time and frequency domains. The 10 minutes of paced breathing were averaged and compared between groups using a Welch’s t-test. Data are expressed as means±SD. P-values < 0.05 are indicated by an asterisk (*). Results: Individuals who regularly use cannabis had a higher heart rate (HR; 70±9 Cannabis vs. 62±8* beats/min Control) and lower HRV measured via standard deviation of normal intervals (SDNN; 66±28 Cannabis vs. 86±24* ms Control). Additionally, individuals who regularly use cannabis exhibited reduced baroreflex sensitivity for both cvBRS-up and cvBRS-down metrics. (cvBRS-up; 15±8 Cannabis vs. 24±10* ms/mmHg Control) (cvBRS-down; 14±6 Cannabis vs. 20±7* ms/mmHg Control). We did not detect significant differences in resting blood pressure or in frequency domain metrics of HRV. Conclusion: At rest, individuals who regularly use cannabis exhibit blunted baroreflex sensitivity and reduced heart rate variability compared to individuals who do not use cannabis. Persistent inhibition of the baroreflex and vagal tone could allow sympathoexcitation to occur without vagal restraint, increasing cardiovascular vulnerability. Thus, impaired vagal modulation of the heart and baroreflex gain may contribute to the increased risk in adverse cardiovascular events associated with regular cannabis use. This abstract was presented at the American Physiology Summit 2026 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.