Slow breathing / device-guided breathing (DGB)

Introduced with the Weng et al. (2021) ingest, and notable for being the wiki’s first body-directed intervention that does not go through awareness at all.

Every other intervention in the applications and methods folders — mindfulness-meditation, interoceptive-exposure, mabt, somatic-experiencing — changes how a person attends to, appraises or tolerates bodily sensation. bioelectronic-medicine bypasses the person entirely by putting current into a nerve. Slow breathing sits in between and is the awkward case: the person performs it voluntarily, but the mechanism as stated is pure reflex physiology, and nothing in it requires them to notice a single sensation.

The mechanism as given

Rate down (~5 breaths/min) → tidal volume up → cardiopulmonary stretch receptors activated → reflex reduction in sympathetic nervous system activation → blood pressure down. Slow breathing additionally improves arterial baroreflex control of SNS activity.

The clinical rationale is sympathetic overactivity, which characterizes chronic kidney disease and PTSD, both of which carry elevated cardiovascular risk, and for which the drug options are poorly tolerated.

The evidence, as reviewed

• DGB acutely reduced blood pressure and muscle sympathetic nerve activity (MSNA) and improved arterial baroreflex sensitivity in veterans with PTSD (Fonkoue et al. 2018) — a group with documented augmented SNS reactivity to mental stress and impaired baroreflex sensitivity (Park et al. 2017).
• 8 weeks of daily DGB reduced sympathetic reactivity to mental stress in PTSD patients (Fonkoue et al. 2020) — the only durable-exposure result here.
• Slow breathing improves baroreflex sensitivity in chronic heart failure (Bernardi et al. 2002) and essential hypertension (Joseph et al. 2005).
• An RCT of mindfulness-based stretching with deep breathing reduced PTSD symptom severity in women with subclinical PTSD (Kim et al. 2013) — with the review’s own caveat that “the exact interoceptive mechanisms are unclear.”

The comparison that matters

In CKD patients, a single mindfulness session including breathing awareness lowered MSNA and blood pressure versus a health-education control; the meditation also lowered respiratory rate, but slow breathing alone did not produce the same reductions (Park et al. 2014).

This is the wiki’s only direct test separating the respiratory manipulation from the attentional one, and it comes out against the manipulation. One study, single session, small sample — but it is exactly the design the wiki has been asking for elsewhere (see the trans-therapeutic null on mindfulness-interoceptive-training), and it cuts the opposite way. Both results are now recorded side by side.

Is this interoception?

Worth asking plainly, because the review files it under interoceptive interventions and the wiki should not simply inherit that. The case for: it manipulates an interoceptive channel, it works via interoceptive afferents (stretch receptors, baroreceptors), and it changes an interoceptive system’s state. The case against: no interoceptive representation, attention, appraisal or awareness is involved or measured; by the same standard, exercise and antihypertensives are interoceptive interventions.

The wiki records it as a manipulation of an interoceptive pathway rather than of interoception — the same distinction drawn on bioelectronic-medicine, and the reason respiratory-interoception exists as a page.