Single-Dose Psilocybin Treatment for Major Depressive Disorder: A Randomized Clinical Trial.

Importance: Psilocybin shows promise as a treatment for major depressive disorder (MDD). Objective: To evaluate the magnitude, timing, and durability of antidepressant effects and safety of a single dose of psilocybin in patients with MDD. Design, Setting, and Participants: In this phase 2 trial conducted between December 2019 and June 2022 at 11 research sites in the US, participants were randomized in a 1:1 ratio to receive a single dose of psilocybin vs niacin placebo administered with psychological support. Participants were adults aged 21 to 65 years with a Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition diagnosis of MDD of at least 60 days' duration and moderate or greater symptom severity. Exclusion criteria included history of psychosis or mania, active substance use disorder, and active suicidal ideation with intent. Participants taking psychotropic agents who otherwise met inclusion/exclusion criteria were eligible following medication taper. Primary and secondary outcomes and adverse events (AEs) were assessed at baseline (conducted within 7 days before dosing) and at 2, 8, 15, 29, and 43 days after dosing. Interventions: Interventions were a 25-mg dose of synthetic psilocybin or a 100-mg dose of niacin in identical-appearing capsules, each administered with psychological support. Main Outcomes and Measures: The primary outcome was change in central rater-assessed Montgomery-Asberg Depression Rating Scale (MADRS) score (range, 0-60; higher scores indicate more severe depression) from baseline to day 43. The key secondary outcome measure was change in MADRS score from baseline to day 8. Other secondary outcomes were change in Sheehan Disability Scale score from baseline to day 43 and MADRS-defined sustained response and remission. Participants, study site personnel, study sponsor, outcome assessors (raters), and statisticians were blinded to treatment assignment. Results: A total of 104 participants (mean [SD] age, 41.1 [11.3] years; 52 [50%] women) were randomized (51 to the psilocybin group and 53 to the niacin group). Psilocybin treatment was associated with significantly reduced MADRS scores compared with niacin from baseline to day 43 (mean difference,-12.3 [95% CI, -17.5 to -7.2]; P <.001) and from baseline to day 8 (mean difference, -12.0 [95% CI, -16.6 to -7.4]; P < .001). Psilocybin treatment was also associated with significantly reduced Sheehan Disability Scale scores compared with niacin (mean difference, -2.31 [95% CI, 3.50-1.11]; P < .001) from baseline to day 43. More participants receiving psilocybin had sustained response (but not remission) than those receiving niacin. There were no serious treatment-emergent AEs; however, psilocybin treatment was associated with a higher rate of overall AEs and a higher rate of severe AEs. Conclusions and Relevance: Psilocybin treatment was associated with a clinically significant sustained reduction in depressive symptoms and functional disability, without serious adverse events. These findings add to increasing evidence that psilocybin-when administered with psychological support-may hold promise as a novel intervention for MDD. Trial Registration: ClinicalTrials.gov Identifier: NCT03866174.

A Systematic Approach to Standardizing Drinking Outcomes From Timeline Followback Data.

Objective: The timeline followback (TLFB) interview is the gold standard for the quantitative assessment of alcohol use. However, self-reported "drinks" can vary in alcohol content. If this variability is not accounted for, it can compromise the reliability and validity of TLFB data. To improve the precision of the TLFB data, we developed a detailed standard operating procedure (SOP) to calculate standard drinks more accurately from participant reports. Method: For the new SOP, the volume and alcohol content by volume (ABV) of distinct types of alcoholic beverages were determined based on product websites and other reliable sources. Recipes for specific cocktails were constructed based on recipes from bartending education websites. One standard drink was defined as 0.6 oz (14 g) of absolute alcohol. Standard drink totals were contrasted for the new SOP approach and the standard procedure, which generally assumed that one self-reported drink was equivalent to one standard drink. Results: Relative to the standard TLFB procedure, higher numbers of standard drinks were reported after implementing the TLFB SOP. Conclusions: Variability in procedures for conversion of self-reported alcohol consumption to standard drinks can confound the interpretation of TLFB data. The use and reporting of a detailed SOP can significantly reduce the potential for such inconsistencies. Detailed and consistent procedures for calculation of standard drinks can enhance the quality of TLFB drinking data.

Psilocybin for alcohol use disorder: Rationale and design considerations for a randomized controlled trial.

Several lines of evidence suggest that classic psychedelics (5-HT2A receptor agonists or partial agonists) such as psilocybin might facilitate behavior change in individuals with substance use disorders. We conducted a multi-site, double-blind, randomized controlled trial (RCT) to assess the effects of psilocybin-assisted psychotherapy in alcohol-dependent volunteers. In addition to a structured 12-week psychotherapy platform, participants (n = 96) were randomly assigned (1:1) to receive either oral psilocybin or an active placebo (oral diphenhydramine) in each of two dosing sessions (at weeks 4 and 8). Initial doses were 25 mg/70 kg psilocybin or 50 mg diphenhydramine, which could be increased in the second session depending on initial response. The psychotherapy platform combined evidence-based, manualized therapy for alcohol dependence with a supportive context for the dosing sessions. All participants were followed in the RCT through week 36. At the end of the RCT, participants who still met safety criteria were offered an open-label psilocybin session. Data collected at screening, baseline and throughout the study included: demographics, measures of alcohol use, subjective response to psilocybin and diphenhydramine, and safety measures. The primary outcome was the proportion of heavy drinking days during the 32 weeks after the first dosing session (i.e., between week 4 and week 36). Secondary outcomes included safety, additional measures of drinking (e.g., abstinence, drinking days, etc.), craving, self-efficacy, and acute effects. We will also explore moderators and mediators of the primary outcome. The primary outcomes will be published elsewhere. In this paper, we describe the protocol and rationale for our design decisions.

Mapping consent practices for outpatient psychiatric use of ketamine.

BACKGROUND: Given increasing community-based and off-label use of ketamine for psychiatric indications, we examined current informed consent processes from a convenience sample of outpatient ketamine clinics to identify areas of congruence with current evidence and opportunities for growth. METHODS: Using a rubric developed from existing practice guidelines, we conducted an exploratory analysis of informed consent documents (IC-Docs) from 23 American clinics offering ketamine as a psychiatric treatment. Domains assessed included clinical content, procedures, and syntax. RESULTS: Participating clinics (23/288) varied widely in their constitution, training, and services provided. We found that IC-Docs addressed a majority of consent elements, though did so variably on an item-level. Areas for improvement included communication around long-term adverse effects, treatment alternatives, medical/psychiatric evaluation prior to treatment, medical/psychological support during treatment, adjunctive psychological interventions, and subjective/dissociative-type effects. All forms were limited by poor readability. LIMITATIONS: Our study was limited by convenience sampling along with possible underestimation of verbal consent processes. CONCLUSIONS: As ketamine continues to emerge as a psychiatric intervention, both patients and providers will benefit from a deliberate consent process informed by scientific, ethical, and pragmatic factors toward the goal of shared decision-making regarding treatment.

Axon degeneration and PGC-1α-mediated protection in a zebrafish model of α-synuclein toxicity.

α-synuclein (aSyn) expression is implicated in neurodegenerative processes, including Parkinson's disease (PD) and dementia with Lewy bodies (DLB). In animal models of these diseases, axon pathology often precedes cell death, raising the question of whether aSyn has compartment-specific toxic effects that could require early and/or independent therapeutic intervention. The relevance of axonal pathology to degeneration can only be addressed through longitudinal, in vivo monitoring of different neuronal compartments. With current imaging methods, dopaminergic neurons do not readily lend themselves to such a task in any vertebrate system. We therefore expressed human wild-type aSyn in zebrafish peripheral sensory neurons, which project elaborate superficial axons that can be continuously imaged in vivo. Axonal outgrowth was normal in these neurons but, by 2 days post-fertilization (dpf), many aSyn-expressing axons became dystrophic, with focal varicosities or diffuse beading. Approximately 20% of aSyn-expressing cells died by 3 dpf. Time-lapse imaging revealed that focal axonal swelling, but not overt fragmentation, usually preceded cell death. Co-expressing aSyn with a mitochondrial reporter revealed deficits in mitochondrial transport and morphology even when axons appeared overtly normal. The axon-protective protein Wallerian degeneration slow (WldS) delayed axon degeneration but not cell death caused by aSyn. By contrast, the transcriptional coactivator PGC-1α, which has roles in the regulation of mitochondrial biogenesis and reactive-oxygen-species detoxification, abrogated aSyn toxicity in both the axon and the cell body. The rapid onset of axonal pathology in this system, and the relatively moderate degree of cell death, provide a new model for the study of aSyn toxicity and protection. Moreover, the accessibility of peripheral sensory axons will allow effects of aSyn to be studied in different neuronal compartments and might have utility in screening for novel disease-modifying compounds.

WldS and PGC-1α regulate mitochondrial transport and oxidation state after axonal injury.

Mitochondria carry out many of the processes implicated in maintaining axon health or causing axon degeneration, including ATP and reactive oxygen species (ROS) generation, as well as calcium buffering and protease activation. Defects in mitochondrial function and transport are common in axon degeneration, but how changes in specific mitochondrial properties relate to degeneration is not well understood. Using cutaneous sensory neurons of living larval zebrafish as a model, we examined the role of mitochondria in axon degeneration by monitoring mitochondrial morphology, transport, and redox state before and after laser axotomy. Mitochondrial transport terminated locally after injury in wild-type axons, an effect that was moderately attenuated by expressing the axon-protective fusion protein Wallerian degeneration slow (WldS). However, mitochondrial transport arrest eventually occurred in WldS-protected axons, indicating that later in the lag phase, mitochondrial transport is not required for axon protection. By contrast, the redox-sensitive biosensor roGFP2 was rapidly oxidized in the mitochondrial matrix after injury, and WldS expression prevented this effect, suggesting that stabilization of ROS production may mediate axon protection. Overexpression of PGC-1α, a transcriptional coactivator with roles in both mitochondrial biogenesis and ROS detoxification, dramatically increased mitochondrial density, attenuated roGFP2 oxidation, and delayed Wallerian degeneration. Collectively, these results indicate that mitochondrial oxidation state is a more reliable indicator of axon vulnerability to degeneration than mitochondrial motility.

Aldehyde dehydrogenase inhibition as a pathogenic mechanism in Parkinson disease.

Parkinson disease (PD) is a neurodegenerative disorder particularly characterized by the loss of dopaminergic neurons in the substantia nigra. Pesticide exposure has been associated with PD occurrence, and we previously reported that the fungicide benomyl interferes with several cellular processes potentially relevant to PD pathogenesis. Here we propose that benomyl, via its bioactivated thiocarbamate sulfoxide metabolite, inhibits aldehyde dehydrogenase (ALDH), leading to accumulation of the reactive dopamine metabolite 3,4-dihydroxyphenylacetaldehyde (DOPAL), preferential degeneration of dopaminergic neurons, and development of PD. This hypothesis is supported by multiple lines of evidence. (i) We previously showed in mice the metabolism of benomyl to S-methyl N-butylthiocarbamate sulfoxide, which inhibits ALDH at nanomolar levels. We report here that benomyl exposure in primary mesencephalic neurons (ii) inhibits ALDH and (iii) alters dopamine homeostasis. It induces selective dopaminergic neuronal damage (iv) in vitro in primary mesencephalic cultures and (v) in vivo in a zebrafish system. (vi) In vitro cell loss was attenuated by reducing DOPAL formation. (vii) In our epidemiology study, higher exposure to benomyl was associated with increased PD risk. This ALDH model for PD etiology may help explain the selective vulnerability of dopaminergic neurons in PD and provide a potential mechanism through which environmental toxicants contribute to PD pathogenesis.

Dynamics of degeneration and regeneration in developing zebrafish peripheral axons reveals a requirement for extrinsic cell types.

BACKGROUND: Understanding the cellular mechanisms regulating axon degeneration and regeneration is crucial for developing treatments for nerve injury and neurodegenerative disease. In neurons, axon degeneration is distinct from cell body death and often precedes or is associated with the onset of disease symptoms. In the peripheral nervous system of both vertebrates and invertebrates, after degeneration of detached fragments, axons can often regenerate to restore function. Many studies of axonal degeneration and regeneration have used in vitro approaches, but the influence of extrinsic cell types on these processes can only be fully addressed in live animals. Because of its simplicity and superficial location, the larval zebrafish posterior lateral line (pLL) nerve is an ideal model system for live studies of axon degeneration and regeneration. RESULTS: We used laser axotomy and time-lapse imaging of pLL axons to characterize the roles of leukocytes, Schwann cells and target sensory hair cells in axon degeneration and regeneration in vivo. Immune cells were essential for efficient removal of axonal debris after axotomy. Schwann cells were required for proper fasciculation and pathfinding of regenerating axons to their target cells. Intact target hair cells were not themselves required for regeneration, but chemical ablation of neuromasts caused axons to transiently deviate from their normal paths. CONCLUSIONS: Macrophages, Schwann cells, and target sensory organs are required for distinct aspects of pLL axon degeneration or regeneration in the zebrafish larva. Our work introduces a powerful vertebrate model for analyzing axonal degeneration and regeneration in the living animal and elucidating the role of extrinsic cell types in these processes.

Generation and behavioral characterization of beta-catenin forebrain-specific conditional knock-out mice.

The canonical Wnt pathway and beta-catenin have been implicated in the pathophysiology of mood disorders. We generated forebrain-specific CRE-mediated conditional beta-catenin knock-out mice to begin exploring the behavioral implications of decreased Wnt pathway signaling in the central nervous system. In situ hybridization revealed a progressive knock-out of beta-catenin that began between 2 and 4 weeks of age, and by 12 weeks resulted in considerably decreased beta-catenin expression in regions of the forebrain, including the frontal cortex, hippocampus, and striatum. A significant decrease in protein levels of beta-catenin in these brain regions was observed by Western blot. Behavioral characterization of these mice in several tests (including the forced swim test, tail suspension test (TST), learned helplessness, response and sensitization to stimulants, and light/dark box among other tests) revealed relatively circumscribed alterations. In the TST, knock-out mice spent significantly less time struggling (a depression-like phenotype). However, knock-out mice did not differ from their wild-type littermates in the other behavioral tests of mood-related or anxiety-related behaviors. These results suggest that a 60-70% beta-catenin reduction in circumscribed brain regions is only capable of inducing subtle behavioral changes. Alternatively, regulating beta-catenin may modulate drug effects rather than being a model of mood disorder pathophysiology per se.

Involvement of AMPA receptors in the antidepressant-like effects of lithium in the mouse tail suspension test and forced swim test.

In addition to its clinical antimanic effects, lithium also has efficacy in the treatment of depression. However, the mechanism by which lithium exerts its antidepressant effects is unclear. Our objective was to further characterize the effects of peripheral and central administration of lithium in mouse models of antidepressant efficacy as well as to investigate the role of alpha-amino-3-hydroxy-5-methyl-4-isoxazole-propionic acid (AMPA) receptors in these behaviors. We utilized the mouse forced swim test (FST) and tail suspension test (TST), intracerebroventricular (ICV) lithium administration, AMPA receptor inhibitors, and BS3 crosslinking followed by Western blot. Both short- and long-term administration of lithium resulted in robust antidepressant-like effects in the mouse FST and TST. Using ICV administration of lithium, we show that these effects are due to actions of lithium on the brain, rather than to peripheral effects of the drug. Both ICV and rodent chow (0.4% LiCl) administration paradigms resulted in brain lithium concentrations within the human therapeutic range. The antidepressant-like effects of lithium in the FST and TST were blocked by administration of AMPA receptor inhibitors. Additionally, administration of lithium increased the cell surface expression of GluR1 and GluR2 in the mouse hippocampus. Collectively, these data show that lithium exerts centrally mediated antidepressant-like effects in the mouse FST and TST that require AMPA receptor activation. Lithium may exert its antidepressant effects in humans through AMPA receptors, thus further supporting a role of targeting AMPA receptors as a therapeutic approach for the treatment of depression.

Targeting signal transduction pathways in the treatment of mood disorders: recent insights into the relevance of the Wnt pathway.

Regulation of complex signaling pathways plays a critical role in higher-order brain functions including the regulation of mood, cognition, appetite, sexual arousal, sleep patterns, and weight, all of which are altered in mood disorders, suggesting the involvement of signaling pathways in mood disorder pathogenesis and pathophysiology. Most existing medications used to treat mood disorders take many weeks to exert their full clinical effects, a fact which implicates changes in gene and protein expression, as well as neuroplasticity, in their mechanism of action. Modulation of signaling pathways has many downstream effects on gene expression and protein function, causing changes in synaptic function, plasticity, and response to various inputs such as neurohormones. The Wnt signaling pathway has recently been linked to the therapeutically relevant actions of available treatments of mood disorders. We provide a brief introduction to signaling cascades and their potential roles in mood disorder pathophysiology and treatment. Subsequently, we describe the Wnt signaling pathway, and glycogen synthase kinase-3 (GSK-3) and beta-catenin specifically, discussing studies that have implicated these proteins as relevant to the pathophysiology and treatment of mood disorders. Future directions, aimed at understanding mood disorders and developing more efficacious treatments, are also discussed.

The behavioral actions of lithium in rodent models: leads to develop novel therapeutics.

For nearly as long as lithium has been in clinical use for the treatment of bipolar disorder, depression, and other conditions, investigators have attempted to characterize its effects on behaviors in rodents. Lithium consistently decreases exploratory activity, rearing, aggression, and amphetamine-induced hyperlocomotion; and it increases the sensitivity to pilocarpine-induced seizures, decreases immobility time in the forced swim test, and attenuates reserpine-induced hypolocomotion. Lithium also predictably induces conditioned taste aversion and alterations in circadian rhythms. The modulation of stereotypy, sensitization, and reward behavior are less consistent actions of the drug. These behavioral models may be relevant to human symptoms and to clinical endophenotypes. It is likely that the actions of lithium in a subset of these animal models are related to the therapeutic efficacy, as well the side effects, of the drug. We conclude with a brief discussion of various molecular mechanisms by which these lithium-sensitive behaviors may be mediated, and comment on the ways in which rat and mouse models can be used more effectively in the future to address persistent questions about the therapeutically relevant molecular actions of lithium.

Beta-catenin overexpression in the mouse brain phenocopies lithium-sensitive behaviors.

Lithium inhibits glycogen synthase kinase-3 (GSK-3) at therapeutic concentrations; however, it is unclear if this inhibition and its downstream effects on specific signaling pathways are relevant to the treatment of bipolar disorder and depression. One of the targets of GSK-3 is the transcription factor beta-catenin. Normally active GSK-3 phosphorylates beta-catenin, leading to its degradation. Inhibition of GSK-3 therefore increases beta-catenin. We have utilized transgenic mice to investigate the behavioral consequences of CNS beta-catenin overexpression. Transgenic mice overexpressing beta-catenin demonstrated behavioral changes similar to those observed following the administration of lithium, including decreased immobility time in the forced swim test (FST). Further, we show that although acute administration of lithium and overexpression of the beta-catenin transgene inhibits d-amphetamine-induced hyperlocomotion, neither lithium nor the beta-catenin transgene prevents d-amphetamine-induced sensitization, as measured by locomotor activity. Both lithium-treated and beta-catenin mice had an elevated response to d-amphetamine following multiple administrations of the stimulant, though the difference in absolute locomotion was maintained throughout the sensitization time-course. Neither acute lithium nor beta-catenin overexpression had an effect on d-amphetamine-induced stereotyped behavior. The results of this study, in which beta-catenin transgenic mice exhibited behaviors identical to those observed in lithium-treated mice, are consistent with the hypothesis that the behavioral effects of lithium in these models are mediated through its direct inhibition of GSK-3 and the consequent increase in beta-catenin. By associating the behavioral effects of lithium with beta-catenin levels, these data suggest that increasing beta-catenin might be a novel therapeutic strategy for mood disorders.

Strain differences in lithium attenuation of d-amphetamine-induced hyperlocomotion: a mouse model for the genetics of clinical response to lithium.

Lithium attenuation of stimulant-induced hyperlocomotion is a rodent model that may be useful both to understand the mechanism of the therapeutic action of lithium and to develop novel lithium-mimetic compounds. To lay the foundation for future investigations into the neurobiology and genetics of lithium as a therapeutic agent, we studied the effect of lithium on d-amphetamine-induced hyperlocomotion in 12 (3 outbred) mouse strains. In our initial screening, mice received either (1) no drugs, (2) LiCl only, (3) d-amphetamine only, or (4) d-amphetamine and LiCl. Whereas there was no significant effect of LiCl alone on locomotion in any strain, there was a large degree of strain variation in the effects of LiCl combined with d-amphetamine. LiCl attenuated d-amphetamine-induced hyperlocomotion in C57BL/6J, C57BL/6Tac, Black Swiss, and CBA/J mice, whereas CD-1, FVB/NJ, SWR/J, and NIH Swiss mice, which were responsive to d-amphetamine, showed no significant effect of LiCl. d-Amphetamine-induced hyperlocomotion in the C3H/HeJ strain was increased by pretreatment with lithium. A subset of strains were treated for 4 weeks with lithium carbonate before the d-amphetamine challenge, and in each of these strains, lithium produced effects identical to those seen following acute administration. Strain responsiveness to lithium was not dependent upon the dose of either d-amphetamine or LiCl. Further, the results are not explained by brain lithium levels, which suggests that these behavioral responses to lithium are under the control of inherent genetic or other biological mechanisms specific to the effects of lithium on brain function.