2026 ECNP Congress

PS01-1150

Breathwork-induced changes in cerebral blood flow, functional connectivity and altered states of consciousness: similarities and differences with psychedelic research

Hana Adolphi — M. Bernardic, A.D. Vlădoiu, D. Carmara, L. Kärtner, G. Oberthür, G. Gründer, C. Schmitz · Central Institute of Mental Health, Department of Molecular Neuroimaging, Mannheim, Germany

2026 ECNP Congress

Background

The phenomenological overlap between high ventilation breathwork (HVB)-induced states and those induced by classical psychedelics, such as non-ordinary states of consciousness (NOSC) [1], raises the question of whether comparable modulations in brain function and physiology exist. Given that acute subjective experiences in psychedelic research are linked to therapeutic outcomes [2], this study is among the first to examine (i) changes in brain function pre-, during-, and post- in-scanner breathwork session, and (ii) the role of acute NOSC.

Methods

Thirty healthy, experienced breathwork practitioners performed self-guided in-scanner HVB (3T Siemens MRI), instructed to breathe abdominally, minimizing chest expansion and head movement. pcASL sequences were acquired immediately before (pre), during (acute), and after (post) the HVB session, while BOLD-fMRI data were acquired immediately following the pre- and post-pcASL sequences. NOSC intensity was assessed after each 12-minute pcASL run using acute subjective intensity (ASI) ratings (Likert scale: 0 = absent to 4 = strong), relative to each participant’s prior maximal HVB-induced experience, and via the 5D-ASC within one hour after the HVB session. Simple t-tests assessed the differences in pre-to-post functional connectivity (FC) or pre-to-acute cerebral blood flow (CBF, pcASL run corresponding to the first maximum ASI rating).

Results

HVB induced alterations in both acute ASI ratings of NOSC (M=3.47 ± 0.63; median = 4; n = 30) and mean 5D-ASC (29.04 ± 14.83 (range = 2.67–55.9)), with most 5D-ASC subscales being positively correlated with the ASI ratings. Results indicate significant reductions in acute global grey matter cerebral blood flow (CBF; 9.81 ± 7.58 vs. 16.24 ± 4.35 ml/100g/min; t(29) = −10.69, p < .001), accompanied by expected increases in heart rate and respiration rate. No significant pre-to-post differences were determined for FC regions corresponding to the default mode network (DMN) derived from the Schaefer (2018) 100 parcel atlas and DMN-FC difference scores showed no significant association with acute CBF changes. However, regression analyses showed that greater decreases in DMN-FC (pre-to-post) were predictive of higher 5D-ASC ratings (β = −4.88, t(27) = −2.07, pre-to-post p = .04) if global signal regression was applied. Spearman correlation revealed no significant relationship between acute reductions in CBF and NOSC as determined by both 5D-ASC and ASI ratings.

Discussion

This study demonstrates that HVB reliably induces NOSC in experienced practitioners and marked reductions in global CBF likely driven by hypocapnia-induced cerebral vasoconstriction. Despite differing mechanistically from serotonin 2A receptor-mediated psychedelic action, the observed effects have parallels with psychedelic research [3]. Yet, the absence of a CBF-NOSC relationship suggests vasoconstriction alone does not drive NOSC, with relevant perfusion changes potentially being regionally specific rather than global [4]. Pre-to-post DMN-FC remained stable, though post-session scanning proximity may have limited detection of lasting network changes. Notably, greater post-HVB reductions in DMN-FC were associated with more intense NOSC. This finding, while tentative given its GSR-dependence, is directionally consistent with psychedelic research linking acute DMN disruption to experiential depth [5]. The results have implications for understanding the neurobiology of non-pharmacological NOSC and for the potential development of breathwork-based therapeutic interventions.

References

  1. Havenith, Martha N et al. “Decreased CO2 saturation during circular breathwork supports emergence of altered states of consciousness.” Communications psychology vol. 3,1 59. 13 Apr. 2025, doi:10.1038/s44271-025-00247-0
  2. Mertens, Lea J et al. “Efficacy and Safety of Psilocybin in Treatment-Resistant Major Depression: The EPISODE Randomized Clinical Trial.” JAMA psychiatry, e260132. 18 Mar. 2026, doi:10.1001/jamapsychiatry.2026.0132
  3. Carhart-Harris, Robin L et al. “Neural correlates of the psychedelic state as determined by fMRI studies with psilocybin.” Proceedings of the National Academy of Sciences of the United States of America vol. 109,6 (2012): 2138-43. doi:10.1073/pnas.1119598109
  4. Kartar, Amy A et al. “Neurobiological substrates of altered states of consciousness induced by high ventilation breathwork accompanied by music.” PloS one vol. 20,8 e0329411. 27 Aug. 2025, doi:10.1371/journal.pone.0329411
  5. Madsen, Martin K et al. “Psilocybin-induced changes in brain network integrity and segregation correlate with plasma psilocin level and psychedelic experience.” European neuropsychopharmacology : the journal of the European College of Neuropsychopharmacology vol. 50 (2021): 121-132. doi:10.1016/j.euroneuro.2021.06.001