Mindfulness meditation and hypnosis both reduce default mode network activity and strengthen connections between the central executive and salience networks in the brain, as shown by MRI studies of stress, anxiety, and depression. A systematic review of 97 studies (84 on mindfulness, 13 on hypnosis) from 2010 to 2022 found that only mindfulness practice and predisposition increase connectivity between the default mode and salience networks, a change not seen in hypnosis. The findings clarify shared and distinct neural mechanisms, but the authors call for more rigorous research.
A single one-hour session of a 50:50 nitrous oxide/oxygen mixture (EMONO) rapidly alters functional connectivity in the default mode network and increases brain tissue pulsations in depressed women who respond to the treatment. Among 20 women with treatment-resistant depression, 45% showed at least a 50% reduction in depression scores one week after exposure. Responders exhibited decreased connectivity between the subgenual anterior cingulate cortex and the precuneus, and a larger early increase in brain tissue pulsations, which may enhance drug delivery. Non-responders and healthy controls showed different connectivity changes. The findings suggest potential cerebral mechanisms and markers for antidepressant response to nitrous oxide.