Journal of Magnetic Resonance Imaging
April 17, 2015
Ekaterina Tchistiakova, David Crane, David J. Mikulis et al.
20 citations
White matter hyperintensities (WMH) are common in older adults and linked to cognitive decline, stroke, and dementia. Vascular risk factors (VRFs) such as high blood pressure contribute to WMH, but their effect on gray matter function is unclear. In 29 participants with suspected WMH, those with more VRFs showed lower cerebrovascular reactivity (CVR) in the default-mode network (DMN), measured using a dual-regression analysis of BOLD imaging during hypercapnia. CVR in the DMN also correlated with resting-state coactivation. No differences were found in sensory-motor or medial-visual networks. The findings suggest that multiple VRFs may impair blood flow regulation in key brain networks.
Trials
July 3, 2024
Joshua M. Poulin, Gregory E. Bigford, Krista L. Lanctôt et al.
3 citations
A proposed randomized controlled trial will test whether a single 25 mg dose of psilocybin, compared to a placebo, acutely alters cerebral blood flow and functional brain activity in mood-regulating networks in people with major depressive disorder or persistent depressive disorder. Fifty participants from a mood disorders clinic will be randomly assigned to receive either psilocybin or a placebo, with the placebo group later crossing over to receive psilocybin. The study will use arterial spin labelling and blood oxygenation level-dependent functional MRI to measure brain changes intraday and at three weeks. Clinical outcomes will be tracked with the Montgomery-Åsberg Depression Rating Scale and other scales. The work aims to clarify psilocybin's neuroplastic mechanisms and identify early brain-based predictors of treatment response.
Research Square
December 28, 2023
Joshua M. Poulin, Gregory E. Bigford, Krista L. Lanctôt et al.
1 citation
About one third of people with depression do not fully respond to standard treatments, and psilocybin may offer a rapid-acting alternative. This registered trial will randomize 36 adults with major depressive or persistent depressive disorder to receive either 25 mg psilocybin or an active placebo (100 mg niacin), then cross over three weeks later so that all participants receive psilocybin. Using serial neuroimaging, the study will test whether psilocybin acutely alters cerebral blood flow and functional brain activity in mood-related networks compared to placebo, and whether those changes persist subacutely. Clinical scales and serum biomarkers will also be collected to explore relationships with treatment response.
Bipolar Disorders
May 1, 2023
William S H Kim, Mikaela K Dimick, Danielle Omrin et al.
In a double-blind randomized controlled trial, 25 adults with bipolar I or II disorder and treatment-resistant depression received either nitrous oxide (25% concentration for 20 minutes) plus intravenous saline or medical air plus intravenous midazolam (2 mg total). No significant between-group differences emerged in depression severity change or treatment response 24 hours after treatment. However, the nitrous oxide group showed significantly greater same-day reductions in depression severity. Lower baseline regional cerebral blood flow predicted greater 24-hour improvement with nitrous oxide but not midazolam. Midazolam was associated with regional cerebral blood flow reductions compared to nitrous oxide. These secondary findings suggest differential associations of the two agents with depression severity and brain hemodynamics, warranting larger studies.
Contemporary clinical trials communications
September 1, 2020
Mikaela K Dimick, Danielle Omrin, Bradley J MacIntosh et al.
A randomized, double-blind trial will test whether a single administration of nitrous oxide (N2O) improves mood and increases frontal cerebral blood flow in adults with treatment-resistant bipolar depression. Participants with bipolar I or II disorder currently in a major depressive episode will be assigned to either inhaled N2O plus intravenous saline or inhaled room air plus intravenous midazolam. Mood will be assessed with the Montgomery-Asberg Depression Rating Scale, and cerebral blood flow measured by arterial spin labelling MRI. The authors suggest N2O may act as a cerebral vasodilator to counteract hypoperfusion in depression, and if effective, could become a low-cost, safe, and accessible acute treatment.