Phase 1, placebo-controlled, single ascending dose trial to evaluate the safety, pharmacokinetics and effect on altered states of consciousness of intranasal BPL-003 (5-methoxy-N,N-dimethyltryptamine benzoate) in healthy participants

AIMS

To investigate the safety, tolerability, pharmacokinetics (PK) and pharmacodynamics (PD) of BPL-003, a novel intranasal benzoate salt formulation of 5-methoxy-N,N-dimethyltryptamine (5-MeO-DMT), in healthy participants.

METHODS

In all, 44 psychedelic-naïve participants enrolled in the double-blind, placebo-controlled single ascending dose study (1-12 mg BPL-003). Concentrations of 5-MeO-DMT and its pharmacologically active metabolite, bufotenine, were determined in plasma and urine. PD endpoints included subjective drug intensity (SDI) rating, the Mystical Experience Questionnaire (MEQ-30) and the Ego Dissolution Inventory (EDI).

RESULTS

BPL-003 was well tolerated at doses up to 12 mg. There were no serious adverse events (AEs), and most AEs were mild; the most common being nasal discomfort, nausea, headache and vomiting. 5-MeO-DMT was rapidly absorbed and eliminated; the median time to peak plasma concentration was approximately 8-10 min and the mean terminal elimination half-life was <27 min. 5-MeO-DMT systemic exposure increased approximately dose-proportionally, while plasma bufotenine concentrations and urinary excretion of 5-MeO-DMT and bufotenine were negligible. The intensity of the SDI ratings was associated with plasma 5-MeO-DMT concentrations. MEQ-30 and EDI scores generally increased with the BPL-003 dose; 60% of participants had a 'complete mystical experience' at 10 and 12 mg doses. Profound and highly emotional consciousness-altering effects were observed with BPL-003, with a rapid onset and short-lasting duration.

CONCLUSION

The novel intranasal formulation of BPL-003 was well tolerated with dose-proportional increases in PK and PD effects. The short duration of action and induction of mystical experiences suggest clinical potential, warranting further trials.

CLINICAL TRIAL REGISTRATION

NCT05347849.

A narrative synthesis of research with 5-MeO-DMT

BACKGROUND

5-Methoxy-N,N-dimethyltryptamine (5-MeO-DMT) is a naturally occurring, short-acting psychedelic tryptamine, produced by a variety of plant and animal species. Plants containing 5-MeO-DMT have been used throughout history for ritual and spiritual purposes. The aim of this article is to review the available literature about 5-MeO-DMT and inform subsequent clinical development.

METHODS

We searched PubMed database for articles about 5-MeO-DMT. Search results were cross-checked against earlier reviews and reference lists were hand searched. Findings were synthesised using a narrative synthesis approach. This review covers the pharmacology, chemistry and metabolism of 5-MeO-DMT, as well epidemiological studies, and reported adverse and beneficial effects.

RESULTS

5-MeO-DMT is serotonergic agonist, with highest affinity for 5-HT_1A receptors. It was studied in a variety of animal models, but clinical studies with humans are lacking. Epidemiological studies indicate that, like other psychedelics, 5-MeO-DMT induces profound alterations in consciousness (including mystical experiences), with potential beneficial long-term effects on mental health and well-being.

CONCLUSION

5-MeO-DMT is a potentially useful addition to the psychedelic pharmacopoeia because of its short duration of action, relative lack of visual effects and putatively higher rates of ego-dissolution and mystical experiences. We conclude that further clinical exploration is warranted, using similar precautions as with other classic psychedelics.

Neighbourhood characteristics and social isolation of people with psychosis: a multi-site cross-sectional study

PURPOSE

People with psychosis are vulnerable to social isolation, which is associated with worse clinical outcomes. In general populations, people living in areas with higher population density have more social contacts, while those living in more socially deprived and fragmented areas are less satisfied with their relationships. We assessed whether and how neighbourhood factors are associated with social contacts and satisfaction with friendships for people with psychosis.

METHODS

We carried out a cross-sectional study including people with psychosis aged 18-65 years in urban and rural sites in England. Population density and social deprivation and fragmentation indexes were described within Lower Level Super Output Areas (LSOA). Their associations with participants' social contacts and satisfaction with friendships were tested with negative binomial and ordinal regression models, respectively.

RESULTS

We surveyed 511 participants with psychotic disorders. They had a median of two social contacts in the previous week (interquartile range [IQR] = 1-4), and rated satisfaction with friendships as 5 out of 7 (Manchester Short Assessment of Quality of Life; IQR = 4-6). Higher population density was associated with fewer social contacts (Z-standardised relative risk [RR] = 0.88; 95% CI = 0.79-0.99, p = 0.03), but not with satisfaction with friendships (RR = 1.08; 95% CI = 0.93-1.26, p = 0.31). No associations were found for social contacts or satisfaction with friendships with social deprivation or fragmentation indexes.

CONCLUSIONS

Clinicians in urban areas should be aware that their patients with psychosis are more socially isolated when more people live around them, and this could impact their clinical outcomes. These findings may inform housing programmes.

Altered subcortical emotional salience processing differentiates Parkinson's patients with and without psychotic symptoms

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Emotional salience processing differentiates PD patients with and without psychosis.

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Enhanced striatal, hippocampal and midbrain responses in PD patients with psychosis.

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Indication for ‘jumping to conclusions’ bias in the same PD patients with psychosis.

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Aberrant top-down and salience processing associated with PD psychosis.

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Similar deficits as proposed in ‘aberrant salience hypothesis’ of schizophrenia.

Objective

Current research does not provide a clear explanation for why some patients with Parkinson’s Disease (PD) develop psychotic symptoms. The ‘aberrant salience hypothesis’ of psychosis has been influential and proposes that dopaminergic dysregulation leads to inappropriate attribution of salience to irrelevant/non-informative stimuli, facilitating the formation of hallucinations and delusions. The aim of this study is to investigate whether non-motivational salience is altered in PD patients and possibly linked to the development of psychotic symptoms.

Methods

We investigated salience processing in 14 PD patients with psychotic symptoms, 23 PD patients without psychotic symptoms and 19 healthy controls. All patients were on dopaminergic medication for their PD. We examined emotional salience using a visual oddball fMRI paradigm that has been used to investigate early stages of schizophrenia spectrum psychosis, controlling for resting cerebral blood flow as assessed with arterial spin labelling fMRI.

Results

We found significant differences between patient groups in brain responses to emotional salience. PD patients with psychotic symptoms had enhanced brain responses in the striatum, dopaminergic midbrain, hippocampus and amygdala compared to patients without psychotic symptoms. PD patients with psychotic symptoms showed significant correlations between the levels of dopaminergic drugs they were taking and BOLD signalling, as well as psychotic symptom scores.

Conclusion

Our study suggests that enhanced signalling in the striatum, dopaminergic midbrain, the hippocampus and amygdala is associated with the development of psychotic symptoms in PD, in line with that proposed in the ‘aberrant salience hypothesis’ of psychosis in schizophrenia.

Cost Evaluation During Decision-Making in Patients at Early Stages of Psychosis

Jumping to conclusions during probabilistic reasoning is a cognitive bias reliably observed in psychosis and linked to delusion formation. Although the reasons for this cognitive bias are unknown, one suggestion is that psychosis patients may view sampling information as more costly. However, previous computational modeling has provided evidence that patients with chronic schizophrenia jump to conclusions because of noisy decision-making. We developed a novel version of the classical beads task, systematically manipulating the cost of information gathering in four blocks. For 31 individuals with early symptoms of psychosis and 31 healthy volunteers, we examined the numbers of "draws to decision" when information sampling had no, a fixed, or an escalating cost. Computational modeling involved estimating a cost of information sampling parameter and a cognitive noise parameter. Overall, patients sampled less information than controls. However, group differences in numbers of draws became less prominent at higher cost trials, where less information was sampled. The attenuation of group difference was not due to floor effects, as in the most costly block, participants sampled more information than an ideal Bayesian agent. Computational modeling showed that, in the condition with no objective cost to information sampling, patients attributed higher costs to information sampling than controls did, Mann-Whitney U = 289, p = 0.007, with marginal evidence of differences in noise parameter estimates, t(60) = 1.86, p = 0.07. In patients, individual differences in severity of psychotic symptoms were statistically significantly associated with higher cost of information sampling, ρ = 0.6, p = 0.001, but not with more cognitive noise, ρ = 0.27, p = 0.14; in controls, cognitive noise predicted aspects of schizotypy (preoccupation and distress associated with delusion-like ideation on the Peters Delusion Inventory). Using a psychological manipulation and computational modeling, we provide evidence that early-psychosis patients jump to conclusions because of attributing higher costs to sampling information, not because of being primarily noisy decision makers.

Brain responses to different types of salience in antipsychotic naïve first episode psychosis: An fMRI study

Abnormal salience processing has been suggested to contribute to the formation of positive psychotic symptoms in schizophrenia and related conditions. Previous research utilising reward learning or anticipation paradigms has demonstrated cortical and subcortical abnormalities in people with psychosis, specifically in the prefrontal cortex, the dopaminergic midbrain and the striatum. In these paradigms, reward prediction errors attribute motivational salience to stimuli. However, little is known about possible abnormalities across different forms of salience processing in psychosis patients, and whether any such abnormalities involve the dopaminergic midbrain. The aim of our study was, therefore, to investigate possible alterations in psychosis in neural activity in response to various forms of salience: novelty, negative emotion, targetness (task-driven salience) and rareness/deviance. We studied 14 antipsychotic naïve participants with first episode psychosis, and 37 healthy volunteers. During fMRI scanning, participants performed a visual oddball task containing these four forms of salience. Psychosis patients showed abnormally reduced signalling in the substantia nigra/ventral tegmental area (SN/VTA) for novelty, negative emotional salience and targetness; reduced striatal and occipital (lingual gyrus) signalling to novelty and negative emotional salience, reduced signalling in the amygdala, anterior cingulate cortex and parahippocamal gyrus to negative emotional salience, and reduced cerebellar signalling to novelty and negative emotional salience. Our results indicate alterations of several forms of salience processing in patients with psychosis in the midbrain SN/VTA, with additional subcortical and cortical regions also showing alterations in salience signalling, the exact pattern of alterations depending on the form of salience in question.

Cortical and Striatal Reward Processing in Parkinson's Disease Psychosis

Psychotic symptoms frequently occur in Parkinson’s disease (PD), but their pathophysiology is poorly understood. According to the National Institute of Health RDoc programme, the pathophysiological basis of neuropsychiatric symptoms may be better understood in terms of dysfunction of underlying domains of neurocognition in a trans-diagnostic fashion. Abnormal cortico-striatal reward processing has been proposed as a key domain contributing to the pathogenesis of psychotic symptoms in schizophrenia. This theory has received empirical support in the study of schizophrenia spectrum disorders and preclinical models of psychosis, but has not been tested in the psychosis associated with PD. We, therefore, investigated brain responses associated with reward expectation and prediction error signaling during reinforcement learning in PD-associated psychosis. An instrumental learning task with monetary gains and losses was conducted during an fMRI study in PD patients with (n = 12), or without (n = 17), a history of psychotic symptoms, along with a sample of healthy controls (n = 24). We conducted region of interest analyses in the ventral striatum (VS), ventromedial prefrontal and posterior cingulate cortices, and whole-brain analyses. There was reduced activation in PD patients with a history of psychosis, compared to those without, in the posterior cingulate cortex and the VS during reward anticipation (p < 0.05 small volume corrected). The results suggest that cortical and striatal abnormalities in reward processing, a putative pathophysiological mechanism of psychosis in schizophrenia, may also contribute to the pathogenesis of psychotic symptoms in PD. The finding of posterior cingulate dysfunction is in keeping with prior results highlighting cortical dysfunction in the pathogenesis of PD psychosis.

Effects of methamphetamine administration on information gathering during probabilistic reasoning in healthy humans

Jumping to conclusions (JTC) during probabilistic reasoning is a cognitive bias repeatedly demonstrated in people with schizophrenia and shown to be associated with delusions. Little is known about the neurochemical basis of probabilistic reasoning. We tested the hypothesis that catecholamines influence data gathering and probabilistic reasoning by administering intravenous methamphetamine, which is known to cause synaptic release of the catecholamines noradrenaline and dopamine, to healthy humans whilst they undertook a probabilistic inference task. Our study used a randomised, double-blind, cross-over design. Seventeen healthy volunteers on three visits were administered either placebo or methamphetamine or methamphetamine preceded by amisulpride. In all three conditions participants performed the "beads" task in which participants decide how much information to gather before making a probabilistic inference, and which measures the cognitive bias towards jumping to conclusions. Psychotic symptoms triggered by methamphetamine were assessed using Comprehensive Assessment of At-Risk Mental States (CAARMS). Methamphetamine induced mild psychotic symptoms, but there was no effect of drug administration on the number of draws to decision (DTD) on the beads task. DTD was a stable trait that was highly correlated within subjects across visits (intra-class correlation coefficients of 0.86 and 0.91 on two versions of the task). The less information was sampled in the placebo condition, the more psychotic-like symptoms the person had after the methamphetamine plus amisulpride condition (p = 0.028). Our results suggest that information gathering during probabilistic reasoning is a stable trait, not easily modified by dopaminergic or noradrenergic modulation.