NEW DATA ON EXTENDING THE EFFFECTS OF IV KETAMINE: Implications for countering the effects of stigma.
John Krystal of Yale U. in an article in Proceedings of the National Academy of Sci. (2023) gave new information about the anatomical and physiological effects of ketamine and about how to extend its effects. Ketamine in animals acutely (in a matter of hours) increases spines, synapses, and dendrites and physiological connectivity in neurons in the prefrontal cortex. Data now support these findings in humans with depression, but AD effects of ketamine tend to dissipate over a period of 3 to 5 days and require repeated infusions to maintain the improvement. Synaptic density can be measured with SV2A and this can be enhanced with a Navitor Pharmaceuticals drug acting on mTORC1. Surprisingly low doses of rapamycin, an inhibitor of mTOR1, extends the duration of AD effects of ketamine, increasing the response rate at 2 weeks of 13% to 41%. Ketamine restores only the spines that have been reduced in depression and rapamycin is thought to extend the duration of the restored spines. It may do this by increasing the neurotropic effects of microglia. The tripartite synapse of pre and post synaptic neurons and astrocytes, may now be better described as the tetrapartite synapse with the inclusion of microglial.
Adding psychotherapy to the effects of ketamine in PTSD increases and extends efficacy.
AD effects of ketamine can be extended with cognitive behavioral therapy. Thus, ketamine increases synaptic efficacy, synaptic density, glutamate homeostasis, and experience-dependent neuroplasticity. Extending the persistence of these effects by various chemical and psychotherapeutic mechanisms may give new ways of enhancing and prolonging the therapeutic effects of this rapidly acting agent.
Interestingly, Kaye at Yale U. reports that in contrast to transient effects of ketamine, the AD effects of therapy-assisted psilocybin appear to be very long lasting and the associated increases in spines persist for longer than 37 days. Another psychedelic MDMA that is effective in PTSD causes large increases in spines, although they are less persistent and are gone by 34 days.
Editors Note: As we have previously highlighted in the BNN, these data on ketamine and other psychedelics reversing the anatomical and physiological deficits in prefrontal neurons of depressed animals and humans (spines, dendrites, synapses and intercellular communication), give a new view of the real, reliable, and replicable neurological defects accompanying depression. The rapid correction of these neural abnormalities in conjunction with the rapid induction of antidepressant effects are not only paradigm shifting from a treatment perspective, but have major implications for the assertion that there is a neurobiological basis of depression and its treatment.
As such, these data should do much to counter the continuing stigma too often accompanying the term “mental” illness that it is somehow not as real as other medical and neurological conditions, and as it is often asserted that “it is just all in one’s head.” This picks up on the unfortunate associations and definitions of “mental” as imaginary, all in the mind, and evanescent and that mental illness can readily be countered with effort and will power such as “pulling oneself up by the bootstraps,” (the latter of which is in itself a logical impossibility.)A Case Report: Good Effect of Psilocybin Even with No Psychedelic Effects
Highlights from the International Society for Bipolar Disorders Conference Posters and Presentations, Chicago, June 22-25, 2023
Marisa Leon-Carlyle reported on a 43 yr. old man with chronic treatment refractory depression who was given psilocybin 25mg (a 5HT2A agonist) at 8:00 AM after receiving trazodone 200mg HS (which should be enough to block 80% of 5HT2A receptors). He had an excellent antidepressant response, was able to feel emotion and new love for his wife, and finally felt that doing one’s best is good enough. Obviously further systematic study is needed.
High Response Rate to Psilocybin in Bipolar II Depression
Highlights from the International Society for Bipolar Disorders Conference Posters and Presentations, Chicago, June 22-25, 2023
Scott Aaronson gave 15 medication-free BP II patients (off all medications) 25mg of psilocybin with extensive therapeutic support. He saw rapid onset and persistent AD effects, such that at the end of 12 weeks 12 of the 15 patients were still in remission. Quality of life increased and suicidal ideation decreased. He indicated that others found that serum BDNF increased 1000 fold greater than baseline.
Antidepressant Effects of Psilocybin in Unipolar Depression
Highlights from the International Society for Bipolar Disorders Conference Posters and Presentations, Chicago, June 22-25, 2023
Alan Young reported on 233 patients with treatment refractory depression who were given 10mg then 25mg of psilocybin, 1 week apart.
There was intensive therapeutic support before, during, and after the ingestions. Patients experienced it as a waking dream. Response was rapid in onset and 20% response persisted at least through week 12.
“Pharmacotherapy of Bipolar Depression”
Roger McIntyre gave a talk on the “Pharmacotherapy of Bipolar Depression” at the International Society for Bipolar Disorders Conference in Chicago, June 22-25, 2023
He pointed out that, contrary to the many approved agents for mania, there were few FDA-approved drugs for depression in patients with Bipolar Disorders. These approved drugs included: cariprazine (Vraylar); lumateperone (Caplyta); lurasidone (Latuda); quetiapine (Seroquel); and the olanzapine-fluoxetine combination (Symbyax). Other non-approved agents include: lithium, lamotrigine, antidepressants, MAOIs, pramipexole, carbamazepine, ketamine, bupropion+dextromethorphan, amantadine, memantine, and possibly minocycline and celecoxib. Surprisingly, more than 3,000 bipolar depressed patients have been reported to be taking ketamine and that this was not associated with the induction of hypomania or mania.
McIntyre reported on the antidepressant (AD) effects of intra-nasal (i.n.) insulin. The insulin receptor sensitizer metformin had AD effects, but only in those who converted to insulin sensitivity.
McIntyre reported on the mixed effects of the GLP-1 agonists in the prevention of depression (Cooper et al J. Psychiatric Res, 2023). This is of interest in relationship to the bidirectional relationship of diabetes mellitus and depression.
Liraglutide appeared to have an anti-anhedonia effect. Semaglutide had AD and antianxiety effects in animal models of depression.
Recent studies have explored the antidepressant effect of psilocybin. Small studies have indicated that it has rapid onset of AD effects, and, in contrast to ketamine where rapid onset AD and anti-suicidal effects are short lived, the AD effect of psilocybin may be more prolonged.
Ketamine repairs structure and function of prefrontal cortical neurons via glutamate NMDA receptor blocking action, while psilocybin and other psychedelics act via stimulating 5HT2A receptors. One single case study suggested that blocking 5HT2A receptors with trazodone could achieve a rapid onset of AD effects of psilocybin without the psychedelic effects, a very interesting finding that requires replication.
An Open Label Study of Synthetic Psilocybin in Bipolar Type II Depression
Highlights from Posters Presented at the Society of Biological Psychiatry Meeting, April 27-29, 2023 in San Diego
Scott Aaronson reported on patients receiving a single dose of synthetic psilocybin. All subjects had three preparatory sessions prior to dosing and three integration sessions post dosing and were followed for 12 weeks.
“At the three week primary outcome measure, 11 of 14 participants (78.6%) met remission criteria.” They concluded: “Most subjects reported significant improvement in chronic depressive symptoms without hypomania or suicidality and durability lasting for three months follow-up.”
Review Describes Latest Findings on the Mechanisms of Psychedelic Drugs and Their Therapeutic Potential
In a 2021 review article in a special issue of the Journal of Neurochemistry devoted to “Psychedelics and Neurochemistry,” researcher Alaina M. Jaster and colleagues summarized recent findings on psychedelic drugs, including their potential as treatments for psychiatric disorders and the structural changes they produce in the brain. The review article focused on findings in humans and provided background context based on findings in animals, particularly rodents.
In the article, Jaster and colleagues write that psychedelics “have in common a battery of acute (within minutes to hours) effects in humans that include profound changes in processes related to perception, cognition, sensory processing, and mood.” They are not considered to be addictive, and recent research has identified fast-acting and long-lasting therapeutic effects of psychedelics, particularly for the treatment of depression and substance abuse.
While psychedelic drugs interact with the brain in complicated ways, the role of serotonin 5-HT2A receptors seems to be crucial to their effects. Psychedelics have classically been divided into two groups based on their chemical structures: phenethylamines (which include mescaline and its synthetic analog DOI) and tryptamines (which include psilocybin/“magic mushrooms,” DMT/ayahuasca, and ergolines like LSD, which are sometimes separated into a third category). The authors of the review highlight that other substances with different chemical structures that do not fit into this classification can also function as psychedelics. Examples include efavirenz and quipazine, which both activate serotonin 5-HT2A receptors and change rodent behavior in the same way that other psychedelic drugs do. These drugs are providing new directions for research into how psychedelics work at both serotonin 5-HT2A receptors and monoaminergic G protein-coupled receptors (GPCRs).
Rodent studies are often used to investigate how psychedelic drugs work. Rodent behaviors such as ear scratching and head twitching increase when the rodents are given drugs that have psychedelic effects in humans. These behaviors return to normal when rodents are given drugs that function as serotonin 5-HT2A receptor antagonists, preventing the stimulation of these serotonin receptors.
While it has been established that serotonin 5-HT2A receptors play an important role in the hallucinogenic effects of psychedelic drugs, how serotonin receptors are involved in some of the therapeutic effects of psychedelics, such as antidepressant effects and changes to synaptic plasticity, is not yet clear.
According to the review, “A number of studies in animal models as well as postmortem human brain samples from subjects with depression and controls has provided evidence that mood disorders occur in conjunction with a reduction in the density of dendritic spines, particularly in the frontal cortex.” Dendrites are the projections from the cell bodies of neurons upon which nerve endings from the axons of other neurons synapse. The surface of these dendrites is covered in mushroom-shaped spines that help create these synaptic connections. The review describes in vitro and in vivo research on mice that suggests that the psychedelics DOI, DMT, and LSD can remodel dendritic spines.
At a recent scientific meeting, researcher Javier González-Maeso, one of the authors of the review, described findings from a recent study of mice given DOI. The structure of the dendritic spines in the prefrontal cortex changed rapidly in these mice. They had also been conditioned to produce a fear response, and the extinction process to get rid of this learned fear was sped up in the mice given DOI. These effects occurred via the serotonin 5-HT2 receptors. The exposure to the psychedelic also affected the regulation of genes involved in synaptic assembly for days, suggesting that epigenetic-induced changes in synaptic plasticity may underlie some of the long-lasting therapeutic effects of psychedelics.
The review also addressed “microdosing,” the recreational practice of consuming small amounts of psychedelics such as psilocybin or LSD, based on the theory that amounts too small to create a hallucinogenic effect may instead produce therapeutic results. The authors find limited data to support microdosing. Most studies in humans and rodents have found no effect or, in the case of one rat study, a worsening of dendritic spine density following microdosing.
