Cerebral haemodynamic correlates of altered consciousness states induced by High-ventilation breathwork

‘Breathwork’ is pursued by a rapidly growing set of adherents, anecdotally because it evokes psychedelic experiences that positively effect mood. We measured regional cerebral blood flow (rCBF) during high-ventilation breathwork (HVB) in healthy participants. Furthermore, we assessed the relationship between rCBF changes and subjective experience, focusing on altered state of consciousness. HVB was associated with substantial global reduction in CBF. Moreover, reduction in rCBF in anterior cingulate and insular cortices scaled with intensity of subjective experiences. These brain regions are implicated in supporting interoceptive control underlying affective regulation. Understanding the neural effects of HVB can inform new clinical applications.