Neuroplasticity, the brain's capacity to reorganise its structure and function, is a transdiagnostic feature across psychiatric and neurodegenerative diseases and a putative mechanism of action for pharmacological interventions. [11C]-UCBJ positron emission tomography (PET), which quantifies synaptic vesicle glycoprotein 2A (SV2A) density, offers the most direct in vivo measure of human...
Abstract Background Clinical studies have shown that ketamine and classic psychedelics can produce robust and rapid antidepressant effects after a single or a few administrations. However, the neurobiological mechanisms driving these long-lasting changes remain unclear. A leading framework proposes that both drug classes induce sustained increases in neuroplasticity, potentially reshaping...
We investigated ketamine's neuroplastic effects in healthy human subjects using integrated Positron Emission Tomography (PET)/Magnetic Resonance Imaging (MRI) measures before and 1-8 days after a single psychedelic dose of ketamine (1 mg/kg, intravenous). Eleven male participants underwent two PET/MRI scans with [11C]-UCBJ (synaptic density/plasticity), 1H-MRS (glutamate and GABA) and...
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Obsessive-compulsive disorder (OCD) is a common and disabling condition. A large proportion of patients fail to respond to first-line treatment with serotonin reuptake inhibitors either selective serotonin reuptake inhibitors (SSRIs) or clomipramine. Preliminary evidence suggests psilocybin, a serotonin receptor agonist, might be efficacious. We conducted a pharmacological challenge study to...
Introduction Psychedelics, such as psilocybin, are increasingly recognized for their propensity to elicit powerful subjective experiences that carry personal meaning. While research has demonstrated the capacity for these compounds to promote psychological wellbeing, it has yet to be shown to what extent they modulate "meaning in life", a specific contributor to mental and physical health....
This study's results are expected to offer critical insights into the neural mechanisms underlying the effects of psilocybin-assisted therapy in treating OCD, and whether these correlate with changes in the cognitive features of the condition. As a secondary aim, it will ascertain whether a low, tolerable dose is a feasible and efficacious clinical treatment, and will provide crucial data to...
Depressive disorders continue to pose a major clinical challenge worldwide, particularly given the high prevalence and increasing number of treatment-resistant cases. Over the past decade, advances in research have elucidated the antidepressant potential of psilocybin and other 5-HT₂A receptor agonists in patients with major depressive disorder (MDD) and treatment-resistant depression (TRD)....
Background: Obsessive-compulsive disorder (OCD) is a complex condition marked by persistent distressing thoughts and repetitive behaviours. Despite its prevalence, the mechanisms behind OCD remain elusive, and current treatments are limited. This protocol outlines an investigative study for individuals with OCD, exploring the potential of psilocybin to improve key components of cognition...
This study investigated the effects of a single high-dose of psilocybin on personality traits in psychedelic-naïve healthy volunteers. These data originate from a larger within-subjects fixed-order design trial, where a single high dose of psilocybin (25 mg) was administered in a psychologically supportive setting and was compared against a (one-month) prior, 1 mg 'placebo' dose. Personality...
Abstract Background Access to psychedelic drugs is liberalizing, yet responses are highly unpredictable. It is therefore imperative that we improve our ability to predict the nature of the acute psychedelic experience to improve safety and optimize potential therapeutic outcomes. This study sought to validate the ‘Imperial Psychedelic Predictor Scale’ (IPPS), a short, widely applicable,...
Background: Reference to an intrinsic healing mechanism or an ‘inner healer’ is commonplace amongst psychedelic drug-using cultures. The ‘inner healer’ refers to the belief that psychedelic compounds, plants or concoctions have an intrinsically regenerative action on the mind and brain, analogous to intrinsic healing mechanisms within the physical body, for example, after sickness or injury....
Abstract Do psychedelics affect sexual functioning postacutely? Anecdotal and qualitative evidence suggests they do, but this has never been formally tested. While sexual functioning and satisfaction are generally regarded as an important aspect of human wellbeing, sexual dysfunction is a common symptom of mental health disorders. It is also a common side effect of selective serotonin reuptake...
Psychedelic drugs such as psilocybin and ketamine are returning to clinical research and intervention across several disorders including the treatment of depression. This chapter focusses on psychedelics that specifically target the 5-HT2A receptor such as psilocybin and DMT. These produce plasma-concentration related psychological effects such as hallucinations and out of body experiences,...
Background: A trial of psilocybin (COMP360) versus escitalopram for major depressive disorder (MDD) was reported as negative, as there was no significant difference in the primary outcome, mean change in the 16-item Quick Inventory of Depressive Symptomatology–Self-Report (QIDS SR-16). However, analyses using three other depression scales (17-item Hamilton Depression Rating Scale [HAMD-17],...
Introduction: As their name suggests, 'psychedelic' (mind-revealing) compounds are thought to catalyse processes of psychological insight; however, few satisfactory scales exist to sample this. This study sought to develop a new scale to measure psychological insight after a psychedelic experience: the Psychological Insight Scale (PIS). Methods: The PIS is a six- to seven-item questionnaire...