Acute effects of subanesthetic ketamine on cerebrovascular hemodynamics in humans: A TD-fNIRS neuroimaging study
Adelaida Castillo, Julien Dubois, Ryan M. Field, Frank Fishburn, Andrew Gundran, Wilson C. Ho, Sami Jawhar, Julian Kates-Harbeck, Zahra M. Aghajan, Naomi Miller, Katherine L. Perdue, Jake Phillips, Wesley C. Ryan, Mahdi Shafiei, Felix Scholkmann, Moriah Taylor
bioRxiv Preprint Server January 6, 2023 preprint DOI: 10.1101/2023.01.06.522912 via bioRxiv
Summary
AI-generated from the abstractKetamine reduced brain-wide low-frequency fluctuations and decreased prefrontal global brain connectivity in healthy adults, while also increasing pulse rate and electrodermal activity. A combination of neural and physiological metrics may predict subjective mystical experiences and reductions in depressive symptoms. The study used time-domain functional near-infrared spectroscopy to measure acute brain dynamics after intramuscular ketamine (0.75 mg/kg) or placebo in 15 participants within a clinical setting, demonstrating the feasibility of this neuroimaging method for larger clinical studies on psychedelics.
Study at a glance
| Characteristics | Single-blind, placebo-controlled study with a non-randomized design |
|---|---|
| Sample size | 15 |
| Population | Healthy participants (8 females, 7 males, age 32.4 ± 7.5 years) |
| Interventions | Ketamine Saline |
| Dose | 0.75 mg/kg |
| Topics | Ketamine |
| Keywords | Psychedelic therapy psychedelics Psychoactive substance Clinical setting Personalized treatments |
| Citations | 3 |
| Key finding | Ketamine caused a brain-wide reduction in the fractional amplitude of low frequency fluctuations and a decrease in global brain connectivity of the prefrontal region, alongside altered consciousness and changes in systemic physiology. |
Abstract
Quantifying neural activity in natural conditions (i.e. conditions comparable to the standard clinical patient experience) during the administration of psychedelics may further our scientific understanding of the effects and mechanisms of action. This data may facilitate the discovery of novel biomarkers enabling more personalized treatments and improved patient outcomes. In this single-blind, placebo-controlled study with a non-randomized design, we use time-domain functional near-infrared spectroscopy (TD-fNIRS) to measure acute brain dynamics after intramuscular subanesthetic ketamine (0.75 mg/kg) and placebo (saline) administration in healthy participants (n = 15, 8 females, 7 males, age 32.4 ± 7.5 years) in a clinical setting. We found that the ketamine administration caused an altered state of consciousness and changes in systemic physiology (e.g. increase in pulse rate and electrodermal activity). Furthermore, ketamine led to a brain-wide reduction in the fractional amplitude of low frequency fluctuations (fALFF), and a decrease in the global brain connectivity of the prefrontal region. Lastly, we provide preliminary evidence that a combination of neural and physiological metrics may serve as predictors of subjective mystical experiences and reductions in depressive symptomatology. Overall, our studies demonstrated the successful application of fNIRS neuroimaging to study the physiological effects of the psychoactive substance ketamine and can be regarded as an important step toward larger scale clinical fNIRS studies that can quantify the impact of psychedelics on the brain in standard clinical settings.