This pre-print (2023) utilizes a novel Bayesian framework to assess autonomic markers, particularly heart rate dynamics, in tracking the effects of psychedelics, including LSD, DMT, psilocybin, and ketamine. The study, encompassing datasets from these drugs, reveals consistent increases in mean heart rate, high-frequency heart rate variability, and heart rate entropy during psychedelic experiences, with these effects demonstrating predictive power over various dimensions of the psychedelic experience. The findings suggest that cost-efficient autonomic measures, particularly heart rate entropy, can provide valuable insights into subjective and brain states during psychedelic experiences, opening new avenues for research in both basic and clinical neuroscience.
Abstract of The entropic heart
“A growing body of work shows that autonomic signals provide a privileged evidence stream to capture various aspects of subjective and neural states. This work investigates the potential for autonomic markers to track the effects of psychedelics – potent psychoactive drugs with important scientific and clinical value. For this purpose, we introduce a novel Bayesian framework to estimate the entropy of heart rate dynamics under psychedelics. We also calculate Bayesian estimates of mean heart rate and heart rate variability, and investigate how these measures relate to subjective reports and neural effects. Results on datasets covering four drugs – lysergic acid diethylamide (LSD), dimethyltryptamine (DMT), psilocybin, and sub-anaesthetic doses of the dissociative agent ketamine – show consistent increases in mean heart rate, high-frequency heart rate variability, and heart rate entropy during the psychedelic experience. Moreover, these effects have predictive power over various dimensions of the psychedelic experience. Changes in heart rate entropy were found to be correlated with increases in brain entropy, while other autonomic markers were not. Overall, our results show that a cost-efficient autonomic measure has the potential to reveal surprising detail about subjective and brain states, opening up a range of new research avenues to explore in both basic and clinical neuroscience.“
Authors: Fernando E. Rosas, Pedro A. M. Mediano, Christopher Timmermann, Andrea I. Luppi, Diego Candia-Rivera, Reza Abbasi-Asl, Adam Gazzaley, Morten L. Kringelbach, Suresh D. Muthukumaraswamy, Daniel Bor, Sarah Garfinkel & Robin L. Carhart-Harris
Summary of The entropic heart: Tracking the psychedelic state via heart rate dynamics
The autonomic nervous system is involved in many bodily processes, including conscious experience and the sense of self. Measurements of heart activity can provide valuable insights into the physiological substrates that support human cognition.
Psychedelic substances are potent psychoactive drugs capable of inducing profound changes in perception, cognition, and conscious experience. The autonomic nervous system offers an essential and complementary evidence stream to enrich our understanding of how psychedelics act to produce their therapeutic and consciousness-altering effects.
This work takes inspiration from empirical findings related to psychedelic brain dynamics and general investigations on heart rate variability (HRV), which both reliably disrupt important markers of spontaneous brain function at wakeful rest and induce a mode of brain function characterised by an enhanced brain entropy. Consistently, work has established a link between the temporal variability of heart beats and health, and metrics of dynamical complexity have been found to extract valuable information from the non-linear aspects of heart rate fluctuations.
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Rosas, F. E., Mediano, P. A., Timmermann, C., Luppi, A. I., Candia-Rivera, D., Abbasi-Asl, R., ... & Carhart-Harris, R. (2023). The entropic heart: Tracking the psychedelic state via heart rate dynamics. bioRxiv, 2023-11.