Changes in cerebral connectivity and brain tissue pulsations with the antidepressant response to an equimolar mixture of oxygen and nitrous oxide: an MRI and ultrasound study

Desmidt, Thomas; Dujardin, Paul-Armand; Andersson, Frédéric; Brizard, Bruno; Réméniéras, Jean-Pierre; Gissot, Valérie; Arlicot, Nicolas; Barantin, Laurent; Espitalier, Fabien; Belzung, Catherine; Tanti, Arnaud; Robert, Gabriel; Bulteau, Samuel; Gallet, Quentin; Kazour, François; Cognet, Sandrine; Camus, Vincent; El-Hage, Wissam; Poupin, Pierre; Karim, Helmet T.

doi:10.1038/s41380-023-02217-6

Cited by 4 publications

References 47 publications

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Elevated brain pulsations in depression: insights from a pooled ultrasound cohort study

Couvreur,

Gallet,

Campion

et al. 2024

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Excessive brain tissue pulsations (BTP), measured by ultrasound, have been associated with depression and are hypothesized to contribute to brain damage in this population at risk for cerebrovascular lesions. However, previous research has been limited by small sample sizes. To address this issue, our study pooled data from three separate investigations, resulting in the largest cohort of depressed participants with BTP measurements to date. We analysed 123 participants (74 individuals with depression and 49 healthy controls) using ultrasound tissue pulsatility imaging (TPI) to assess resting BTP. Results showed that both MeanBTP and MaxBTP were significantly associated with depression, as determined by multiple linear regression models that included age, sex and blood pressure as covariates. Additionally, we found that age, sex and diastolic blood pressure were significant predictors of BTP. Specifically, BTP decreased with age, was higher in men, and was more strongly predicted by diastolic blood pressure than by systolic blood pressure. In this large cohort, we replicated the association between depression and increased BTP, supporting the notion that elevated BTP may be a potential mechanism underlying brain damage over time. Our findings suggest that TPI could serve as a valuable surrogate marker for brain health in clinical practice.

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Elevated brain pulsations in depression: insights from a pooled ultrasound cohort study

Couvreur,

Gallet,

Campion

et al. 2024

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A brief history of the development of transcranial tissue Doppler ultrasound

Nicholls,

Lecchini-Visintini,

Ince

et al. 2024

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This article documents the early development of the first transcranial Doppler (TCD)-based ultrasound system for continuous monitoring of brain tissue pulsations (BTPs). Transcranial tissue Doppler (TCTD) uses a lightweight, wearable single-element ultrasound probe to track tissue motion perpendicular to the skin’s surface, providing tissue displacement estimates along a single beam line. Feasibility tests using an adapted TCD system confirmed that brain tissue motion data can be obtained from existing TCD hardware. Brain Tissue Velocimetry (Brain TV), a TCTD data acquisition system, was then developed to provide a lightweight and portable means of continuously recording TCTD data in real-time. Brain TV measurements are synchronized to a 3-lead electrocardiogram and can be recorded alongside other physiological measurements, such as blood pressure, heart rate and end-tidal carbon dioxide. We have shown that Brain TV is able to record BTPs from sample depths ranging from 22 to 80 mm below the probe’s surface and from multiple positions on the head. Studies in healthy volunteers, stroke patients and ultrasound phantom brain models demonstrate how TCTD might provide insights into the relationships between physiological measurements and brain tissue motion and show promise for rapid clinical assessment and continuous monitoring of BTPs.

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Nitrous Oxide Alters Functional Connectivity in Medial Limbic Structures in Treatment-Resistant Major Depression

Conway,

Palanca,

Zeffiro

et al. 2024

Preprint

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While nitrous oxide (N2O) has demonstrated antidepressant properties in treatment-resistant major depression (TRD), little is known about neural mechanisms mediating these effects. Employing serial resting-state functional magnetic resonance imaging (rsfMRI), we compared spatiotemporal effects of inhaled N2O on brain functional connectivity in TRD patients (n=14) and non-depressed healthy controls (n=16, CNTL). Participants received sequential, one-hour inhalations of either 50% N2O/oxygen or air/oxygen (placebo), with sessions separated by at least one month in random cross-over order. BOLD-contrast rsfMRI scans were acquired at three time points: pre-inhalation, 2 hours post-inhalation, and 24 hours post-inhalation. For the rsfMRI functional connectivity analyses, five a priori seeds in medial limbic structures targeted cortical networks implicated in major depression, the salience, anterior and posterior default mode, reward, and cingulo-opercular networks, and a nexus in the dorsal paracingulate region previously identified in MDD (dorsal nexus). Depression, dissociation, and psychosis assessments were made before and after inhalations. In TRD patients, functional connectivity was reduced in all seeded networks and the voxel-wise global analysis after N2O exposure. N2O progressively decreased connectivity in patients with TRD but increased connectivity in healthy controls. In TRD patients, each seeded network demonstrated post-inhalation functional connectivity reductions in the dorsal paracingulate gyrus (dorsal nexus). This study further elucidates neural mechanisms underlying the antidepressant properties of N2O, supporting the notion that N2O specifically alters mood-associated brain regions in the depressed brain state by reducing functional connectivity within these brain networks.

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Changes in cerebral connectivity and brain tissue pulsations with the antidepressant response to an equimolar mixture of oxygen and nitrous oxide: an MRI and ultrasound study

Cited by 4 publications

References 47 publications

Elevated brain pulsations in depression: insights from a pooled ultrasound cohort study

Elevated brain pulsations in depression: insights from a pooled ultrasound cohort study

A brief history of the development of transcranial tissue Doppler ultrasound

Nitrous Oxide Alters Functional Connectivity in Medial Limbic Structures in Treatment-Resistant Major Depression

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