The International Journal of Neuropsychopharmacology
July 9, 2019
Maggie Fedgchin, Madhukar H. Trivedi, Ella Daly et al.
593 citations
In a phase 3 trial of 346 adults with moderate-to-severe treatment-resistant depression, adding esketamine nasal spray (56 or 84 mg twice weekly) to a new oral antidepressant for 4 weeks did not significantly reduce depression scores compared to adding placebo nasal spray. The 84 mg dose failed to separate from placebo on the primary outcome, and the 56 mg dose could not be formally tested due to the statistical hierarchy. However, the magnitude of improvement with both esketamine doses exceeded what is typically considered clinically meaningful for approved antidepressants. Common side effects included nausea, dissociation, dizziness, vertigo, and headache. The authors conclude the results provide supportive evidence for esketamine's safety and efficacy in treatment-resistant depression.
The International Journal of Neuropsychopharmacology
August 26, 2020
Dawn F. Ionescu, Dong-Jing Fu, Xin Qiu et al.
411 citations
In severely depressed adults with active suicidal thoughts and intent, adding esketamine nasal spray to standard care (hospitalization and new antidepressants) produced a greater reduction in depressive symptoms than placebo plus standard care. At 24 hours, depression scores dropped an average of 15.7 points with esketamine versus 12.4 points with placebo. Improvement was also seen at 4 hours. Both groups showed rapid decreases in suicidality severity, but the difference between them was not statistically significant. Common side effects of esketamine included dizziness, dissociation, nausea, and headache.
The International Journal of Neuropsychopharmacology
October 31, 2014
A. E. Lepack, M. Fuchikami, J. M. Dwyer et al.
369 citations
Ketamine's rapid antidepressant effects depend on the release of brain-derived neurotrophic factor (BDNF) in the medial prefrontal cortex (mPFC), which is triggered by activation of L-type voltage-dependent calcium channels (VDCCs). Infusing a neutralizing BDNF antibody into the mPFC blocked ketamine's behavioral effects in the forced swim test. Pretreatment with either nifedipine or verapamil, two different L-type calcium channel antagonists, also blocked these effects. In primary cortical neurons, ketamine stimulated BDNF release, and this release was prevented by inhibiting AMPA receptors or L-type VDCCs. The findings indicate that L-type VDCC activation and BDNF release mediate ketamine's antidepressant actions.
The International Journal of Neuropsychopharmacology
March 17, 2009
Sanjay J. Mathew, James W. Murrough, Marije Aan Het Rot et al.
295 citations
A single intravenous dose of ketamine (0.5 mg/kg) produced rapid antidepressant effects in patients with treatment-resistant major depression, with 65% responding at 24 hours and 54% at 72 hours. Pretreatment with lamotrigine did not reduce ketamine's mild side effects or improve its antidepressant action. In a subsequent randomized trial, riluzole (100-200 mg/day) failed to prevent relapse over 32 days; 80% of riluzole-treated patients relapsed versus 50% on placebo, leading to early termination. Ketamine appears well-tolerated and rapidly effective, but better strategies to sustain its benefits are needed.
The International Journal of Neuropsychopharmacology
March 12, 2020
Erwin Krediet, Tijmen Bostoen, Joost J. Breeksema et al.
262 citations
Posttraumatic stress disorder (PTSD) often remains chronic after psychotherapy, and few effective medications exist. A promising new approach involves psychedelic drugs. This review discusses four compound types: MDMA, ketamine, classical psychedelics (psilocybin, LSD), and cannabinoids. It describes each compound's therapeutic rationale, administration setting, and current evidence for treating PTSD. Each offers unique qualities, from rapidly targeting symptoms to facilitating psychotherapy. The review outlines questions for future research.
The International Journal of Neuropsychopharmacology
June 7, 2012
Wallace C. Duncan, Simone Sarasso, Fabio Ferrarelli et al.
253 citations
A single infusion of the NMDA receptor antagonist ketamine rapidly reduces depressive symptoms in patients with treatment-resistant major depressive disorder. In 30 patients, ketamine increased electroencephalogram slow wave activity during early non-REM sleep and raised plasma levels of brain-derived neurotrophic factor. The occurrence of high amplitude slow waves and their slope also increased, indicating enhanced synaptic strength. Changes in BDNF levels correlated with changes in EEG parameters, but only in patients who responded to ketamine. This suggests that enhanced synaptic plasticity, reflected by increased slow wave activity and BDNF, is part of the mechanism behind ketamine's rapid antidepressant effects.
The International Journal of Neuropsychopharmacology
October 8, 2013
Colin N. Haile, James W. Murrough, Dan V. Iosifescu et al.
251 citations
In patients with treatment-resistant depression, ketamine increased blood levels of brain-derived neurotrophic factor (BDNF) in those who responded to the drug, compared to non-responders, 240 minutes after infusion. Higher BDNF levels were strongly linked to lower depression scores at multiple time points up to 72 hours. No such associations appeared in patients given the anesthetic midazolam. The findings support BDNF as a marker of ketamine's antidepressant effects.
The International Journal of Neuropsychopharmacology
October 21, 2022
James J Gattuso, Daniel Perkins, Simon Ruffell et al.
233 citations
Classical psychedelics like LSD, psilocybin, and ayahuasca consistently disrupt resting-state connectivity within the Default Mode Network (DMN) and increase functional connectivity between canonical resting-state networks. The DMN, a set of brain regions active during self-referencing and mind wandering, is altered in various neuropsychiatric conditions. While DMN modulation is central to some cognitive models of psychedelics, its role in their therapeutic potential remains unclear. This systematic review provides a comprehensive overview to guide future research on the neurocognitive mechanisms of these agents.
The International Journal of Neuropsychopharmacology
May 17, 2017
Frederic Sampedro, Mario de la Fuente Revenga, Marta Valle et al.
205 citations
A single dose of ayahuasca reduced glutamate+glutamine, creatine, and N-acetylaspartate+N-acetylaspartylglutamate in the posterior cingulate cortex of 16 healthy volunteers, measured post-acutely with magnetic resonance spectroscopy. Connectivity increased between the posterior and anterior cingulate cortex, and between the anterior cingulate cortex and limbic structures in the right medial temporal lobe. Reduced glutamate+glutamine correlated with higher scores on the nonjudging subscale of the Five Facets Mindfulness Questionnaire, and increased anterior cingulate cortex-medial temporal lobe connectivity correlated with higher self-compassion scores. Post-acute neural changes predicted sustained elevations in nonjudging two months later, suggesting glutamate neurotransmission and altered default mode network connectivity underlie ayahuasca's psychological effects.
The International Journal of Neuropsychopharmacology
June 14, 2017
Thomas Pokorny, Katrin H. Preller, Michael Kometer et al.
202 citations
A single dose of psilocybin (0.215 mg/kg) increased emotional empathy in healthy adults but did not affect cognitive empathy or moral decision-making. The rise in implicit emotional empathy correlated with psilocybin-induced changes in the meaning of percepts. These results suggest psilocybin selectively enhances emotional empathy, likely through serotonin 2A/1A receptor activation, which may inform treatments for impaired social cognition.
The International Journal of Neuropsychopharmacology
November 24, 2011
Jason M. Dwyer, Ashley E. Lepack, Ronald S. Duman
169 citations
A single dose of LY 341495, an mGluR₂/₃ antagonist, rapidly activates the mTOR pathway and increases synaptic proteins in the prefrontal cortex, similar to the fast-acting antidepressant ketamine. Within one hour, LY 341495 activates mTOR, p70S6K, and 4E-BP1, and 24 hours later elevates levels of PSD-95, GluR1, and Synapsin I. The antidepressant effects of LY 341495 in the rat forced swim test are completely blocked by the mTOR inhibitor rapamycin, indicating that these actions are mediated by mTOR activation. This suggests mGluR₂/₃ antagonists could produce rapid antidepressant effects in depressed patients.
The International Journal of Neuropsychopharmacology
September 24, 2009
Paolo Fusar‐poli, Paul Allen, Sagnik Bhattacharyya et al.
165 citations
Cannabidiol (CBD), but not delta-9-tetrahydrocannabinol (THC), disrupts forward connectivity between the amygdala and the anterior cingulate cortex during the neural response to fearful faces. This disruption may represent a neurophysiological correlate of CBD's anxiolytic properties. The study used dynamic causal modelling and Bayesian model selection to analyze effective connectivity in 15 healthy subjects under a double-blind, randomized, placebo-controlled fMRI paradigm while they viewed faces eliciting different levels of anxiety.
The International Journal of Neuropsychopharmacology
November 14, 2018
Bashkim Kadriu, Laura Musazzi, Ioline D. Henter et al.
164 citations
Dysfunctional glutamatergic neurotransmission may underlie the pathophysiology of both major depressive disorder and bipolar depression. A single intravenous infusion of the glutamatergic modulator ketamine elicits fast-acting, robust, and relatively sustained antidepressant, antisuicidal, and antianhedonic effects in individuals with treatment-resistant depression. Ketamine's targets include noncompetitive N-methyl-D-aspartate receptor inhibition, α-amino-3-hydroxy-5-methyl-4-isoxazole-propionic acid throughput potentiation, and N-methyl-D-aspartate receptor targets on gamma-aminobutyric acid-ergic interneurons. This review describes ketamine and other novel glutamate-based treatments for treatment-resistant depression, including N-methyl-D-aspartate receptor antagonists, glycine binding site ligands, metabotropic glutamate receptor modulators, and other glutamatergic modulators, along with their putative mechanisms and clinically relevant studies.
The International Journal of Neuropsychopharmacology
May 30, 2019
Nadia R. P. W. Hutten, Natasha L. Mason, Patrick C. Dolder et al.
132 citations
A survey of 1,116 people who microdose psychedelics found that performance enhancement was the main motive (37%), with LSD (10 mcg) and psilocybin (0.5 g) used 2-4 times per week. Most users were unaware of their exact dose. Negative effects were mostly psychological and occurred acutely while under the influence, but the primary reason for stopping microdosing was that it was not effective. The authors call for placebo-controlled studies to quantify performance effects and assess longer-term negative effects.
The International Journal of Neuropsychopharmacology
October 8, 2013
Cédric M. Hysek, Linda D. Simmler, Nathalie Schillinger et al.
125 citations
Taking methylphenidate (Ritalin) with MDMA (ecstasy) does not produce stronger psychoactive effects than either drug alone, but it does increase cardiovascular strain and adverse effects. In a double-blind, placebo-controlled crossover trial with healthy subjects, methylphenidate alone produced psychostimulant effects but did not enhance MDMA's mood-elevating effects. MDMA (125 mg) increased positive mood more than methylphenidate (60 mg), while methylphenidate enhanced activity and concentration more than MDMA. The drugs also differently affected emotion recognition: methylphenidate improved recognition of sad and fearful faces, whereas MDMA reduced recognition of negative emotions. Acute tolerance developed to MDMA but not methylphenidate. The drugs did not alter each other's pharmacokinetics.
The International Journal of Neuropsychopharmacology
August 1, 2010
Nicolas Tournier, Lucie Chevillard, Bruno Mégarbane et al.
122 citations
Several drugs used in addiction treatment and substances of abuse inhibit the efflux transporters P-glycoprotein (P-gp) and breast cancer resistance protein (BCRP) in vitro, which could alter their distribution in the body, including across the blood-brain barrier. Norbuprenorphine, buprenorphine, methadone, ibogaine, and THC inhibited P-gp in a concentration-dependent manner, with norbuprenorphine being the strongest. Buprenorphine, norbuprenorphine, ibogaine, and THC inhibited BCRP. Cocaine, amphetamine, nicotine, morphine, and others did not inhibit either transporter. Norbuprenorphine and methadone were transported by P-gp, but no tested compounds were transported by BCRP. The clinical relevance of norbuprenorphine's interaction with P-gp remains unclear.
The International Journal of Neuropsychopharmacology
October 7, 2016
Chao Dong, Ji-Chun Zhang, Wei Yao et al.
116 citations
MGS0039, a metabotropic glutamate 2/3 receptor antagonist, produces rapid and sustained antidepressant effects in mice subjected to social defeat stress, similar to the well-known antidepressant ketamine. A single dose of either drug reversed depression-like behaviors—reducing immobility in tail suspension and forced swimming tests within 1–2 days and restoring sucrose preference over 3–7 days. Both compounds also reversed reductions in brain-derived neurotrophic factor, TrkB signaling, glutamate receptor subunits, and spine density in the prefrontal cortex, dentate gyrus, and CA3 region of the hippocampus, but not in the nucleus accumbens. These findings suggest that MGS0039 may offer a novel antidepressant mechanism through lasting synaptic changes in specific brain regions.
The International Journal of Neuropsychopharmacology
November 14, 2017
Yukihiko Shirayama, Kenji Hashimoto
113 citations
A single dose of (R)-ketamine (20 mg/kg) produced an antidepressant effect in a rat learned helplessness model of depression. In contrast, neither (R)-norketamine (20 mg/kg) nor (2R,6R)-hydroxynorketamine (20 and 40 mg/kg) showed such effects. These results indicate that the metabolism of ketamine to hydroxynorketamine is not essential for its antidepressant actions, contradicting previous claims.
The International Journal of Neuropsychopharmacology
June 24, 2015
Patrick C. Dolder, Yasmin Schmid, Manuel Haschke et al.
110 citations
Oral lysergic acid diethylamide (LSD) shows dose-proportional pharmacokinetics, with peak concentrations reached about 1.5 hours after ingestion and a terminal half-life of approximately 3.6 hours. The drug's effects are closely related to its blood concentration, with subjective effects lasting up to 12 hours. These findings provide a reference for clinical studies and for assessing LSD intoxication.
The International Journal of Neuropsychopharmacology
December 17, 2013
Robin Carhart-Harris, Matthew B. Wall, David Erritzøe et al.
110 citations
MDMA (ecstasy) makes recalling favorite autobiographical memories feel more vivid, emotionally intense, and positive, while making recall of worst memories feel less negative. In a double-blind, placebo-controlled fMRI study with 19 participants who had prior MDMA experience, 100 mg of MDMA altered brain activity during memory recall: it increased activation in the fusiform gyrus and somatosensory cortex for favorite memories and decreased activation in the left anterior temporal cortex for worst memories. These neural changes suggest MDMA creates a positive emotional bias, which may explain why it helps patients revisit traumatic memories during psychotherapy for PTSD.
The International Journal of Neuropsychopharmacology
March 29, 2015
Joan Francesc Alonso, Sergio Romero, Miguel Ángel Mañanas et al.
105 citations
Ayahuasca, a psychedelic containing the serotonergic 5-HT2A agonist N,N-dimethyltryptamine, temporarily disrupts neural hierarchies in the human brain by reducing top-down control and increasing bottom-up information transfer. In ten healthy male volunteers with prior psychedelic experience, transfer entropy analysis of brain oscillations showed that frontal sources decreased their influence over central, parietal, and occipital sites, while posterior sources increased their influence over anterior locations. Decreases in anterior-to-posterior transfer entropy correlated with the intensity of subjective effects, and the imbalance between anterior-to-posterior and posterior-to-anterior transfer entropy correlated with the degree of incapacitation experienced.
The International Journal of Neuropsychopharmacology
November 1, 2011
Giacomo Salvadore, Jan Willem van der Veen, Yan Zhang et al.
105 citations
Pretreatment levels of certain amino-acid neurotransmitters in the prefrontal cortex predict how well patients with major depressive disorder respond to a single intravenous infusion of ketamine. In fourteen drug-free patients, a lower ratio of glutamine to glutamate in the dorsomedial/dorsal anterolateral prefrontal cortex was associated with greater improvement in depressive symptoms 230 minutes after ketamine administration. Higher glutamate levels in the ventromedial prefrontal cortex correlated with greater improvement in anxiety symptoms. The findings suggest that the presence of reduced glial cells, reflected by the lower glutamine-to-glutamate ratio, may indicate which patients are more likely to benefit from ketamine treatment.
The International Journal of Neuropsychopharmacology
November 4, 2022
Aaron Klaiber, Friederike Holze, Ioanna Istampoulouoglou et al.
100 citations
Lysergic acid diethylamide (LSD) produces its acute psychedelic effects by stimulating the serotonin 5-HT2A receptor. In a double-blind, randomized, placebo-controlled, crossover study with 24 healthy participants, the 5-HT2A antagonist ketanserin (40 mg orally) was given one hour after LSD (100 µg orally). Ketanserin reversed the acute response to LSD, reducing the duration of subjective effects from 8.5 hours with placebo to 3.5 hours. It also reversed LSD-induced alterations of mind, including visual and acoustic alterations and ego dissolution, and reduced adverse cardiovascular effects and mydriasis. Ketanserin did not alter LSD's pharmacokinetics or its elevation of brain-derived neurotrophic factor levels. The findings indicate that LSD produces its psychedelic effects only when occupying 5-HT2A receptors, and ketanserin can shorten and attenuate the LSD experience for research and therapy.
The International Journal of Neuropsychopharmacology
November 16, 2020
Bashkim Kadriu, Maximillian Greenwald, Ioline D. Henter et al.
98 citations
Both the anesthetic ketamine and classic serotonergic psychedelics such as psilocybin may produce rapid and sustained antidepressant effects after a transient psychoactive period. Evidence suggests a potentially shared mechanism wherein both types of drugs engender rapid neuroplastic effects in a glutamatergic activity-dependent manner. They appear to produce acute alterations in cortical network activity that may initially cause psychoactive effects and later produce milder, sustained changes in network efficiency associated with therapeutic response. However, the connection between psychoactive impact and antidepressant efficacy remains unclear and requires more rigorous research. Rapid-acting antidepressants currently under investigation may share downstream pharmacological effects, suggesting related mechanisms of action.
The International Journal of Neuropsychopharmacology
July 16, 2019
Yukio Ago, Wataru Tanabe, Momoko Higuchi et al.
91 citations
Ketamine enantiomers and their metabolites differentially affect monoamine neurotransmitter release in the mouse prefrontal cortex. (R)-ketamine more strongly increases serotonin release than (S)-ketamine, while (S)-ketamine produces a larger increase in dopamine release. Both enantiomers increase noradrenaline release to a similar extent. The metabolite (2R,6R)-HNK slightly increases serotonin and noradrenaline but not dopamine release, whereas (S)-NK increases dopamine and noradrenaline but not serotonin. An AMPA receptor antagonist blocks (S)-ketamine-induced serotonin release and dopamine release by both enantiomers, but not (R)-ketamine-induced serotonin release, indicating (R)-ketamine acts through an AMPA receptor-independent mechanism. These findings reveal neurochemical differences underlying the pharmacological profiles of ketamine enantiomers and their metabolites.