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Rationale: Methamphetamine addiction is a persistent and intractable pathological learning and memory, whereas no approved therapeutics is available. However, few attentions have been paid to how associative learning participates in the formation of intractable memory related to drug addiction OBJECTIVES AND METHODS: To investigate the role of associative learning in methamphetamine addiction and the underlying neurobiological mechanism, methamphetamine self-administration, oral sucrose self-administration, chemogenetic neuromanipulation, and fiber photometry in mice were performed in this study., Results: We reported that associative learning increased methamphetamine-induced self-administration, but not oral sucrose self-administration. In addition, the enhancement of methamphetamine-induced self-administration was independent of more methamphetamine consumption, and remained with higher drug-taking and motivation in the absence of visual cues, suggesting the direct effects of the associative learning that enhanced methamphetamine-induced self-administration. Moreover, chemogenetic inactivation of the secondary visual cortex (V2) reduced the enhancement of the drug-taking induced by associative learning but did not alter sucrose-taking. Further fiber photometry of V2 neurons demonstrated that methamphetamine-associative learning elicits V2 neuron excitation, and sucrose-associative learning elicits V2 neuron inhibition., Conclusions: Therefore, this study reveals the neurobiological mechanism of V2 excitability underlying how associative learning participates in the formation of intractable memory related to drug addiction, and gives evidence to support V2 as a promising target for stimulation therapy for methamphetamine addiction., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Rationale: Theories of addiction guide scientific progress, funding priorities, and policy development and ultimately shape how people experiencing or recovering from addiction are perceived and treated. Choice theories of addiction are heterogenous, and different models have divergent implications. This breeds confusion among laypeople, scientists, practitioners, and policymakers and reduces the utility of robust findings that have the potential to reduce the global burden of addiction-associated harms., Objective: Here we differentiate classes of choice models and articulate a novel framing for a class of addiction models, called contextual models, which share as a first principle the influence of the environment and other contextual factors on behavior within discrete choice contexts., Results: These models do not assume that all choice behaviors are voluntary, but instead that both proximal and distal characteristics of the choice environment-and particularly the benefits and costs of both drug use and non-drug alternatives-can influence behavior in ways that are outside of the awareness of the individual. From this perspective, addiction is neither the individual's moral failing nor an internal uncontrollable urge but rather is the result of environmental contingencies that reinforce the behavior., Conclusions: Contextual models have implications for guiding research, practice, and policy, including identification of novel target mechanisms while also improving existing interventions., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Synthetic cannabinoid receptor agonists (SCRAs) may be used as an alternative to natural cannabis; however, they may carry a greater risk of problematic use and withdrawal. This study aimed to characterise the withdrawal symptom profile of SCRAs and compare their profile of effect with high-potency herbal cannabis. Global Drug Survey data (2015 and 2016) were used to access a clinically relevant sample of people reporting use of SCRAs >10 times in the past 12-months, a previous SCRA quit attempt, and lifetime use of high-potency herbal cannabis. Participants completed an 11-item SCRA withdrawal symptom checklist and compared SCRAs and high-potency herbal cannabis on their onset and duration of effects, speed of the development of tolerance, severity of withdrawal, and difficulty with dose titration. Participants (n = 284) reported experiencing a mean of 4.4 (95% CI: 4.1, 4.8) withdrawal symptoms after not using SCRAs for >1 day; most frequently reported were sleep issues (59.2%), irritability (55.6%), and low mood (54.2%). Withdrawal symptoms were significantly associated with frequency (>51 vs. 11-50 times per year: IRR = 1.43, 95% CI: 1.16, 1.77, p = 0.005) and quantity (grams per session: IRR = 1.13, 95% CI: 1.05, 1.22, p = 0.001) of SCRA use. Compared to high-potency herbal cannabis, SCRAs were rated as having a faster onset and shorter duration of effects, faster development of tolerance, and more severe withdrawal (p's < 0.001). In conclusion, SCRA withdrawal symptoms are more likely to occur after greater SCRA exposure. The effects of SCRA indicate a more severe withdrawal syndrome and a greater risk of problematic use than natural cannabis., (© 2021. The Author(s).)

Rationale: There has been increasing attention on cannabis use for medical purposes, but there is currently a lack of data on its epidemiology., Objectives: To examine the epidemiology of self-reported cannabis use for medical purposes by (1) estimating its prevalence, (2) comparing gender and age differences, and (3) investigating what reasons they were used to manage., Methods: Participants included 27,169 respondents (aged 16-65) who completed Wave 1 of The International Cannabis Policy Study (ICPS) conducted across Canada and the USA in 2018 via online surveys. Cannabis policy conditions were "US legal-recreational" (legal for both recreational and medical uses), "US legal-medical only", "US illegal", and "Canada-medical only"., Results: The overall prevalence of self-reported ever cannabis use for medical purposes was 27%, with similar rates by sex and the highest prevalence in young adults. Prevalence was higher in US legal-recreational states (34%) than US illegal states (23%), US legal-medical only states (25%), and Canada (25%). The most common physical health reasons include use to manage pain (53%), sleep (46%), headaches/migraines (35%), appetite (22%), and nausea/vomiting (21%). For mental health reasons, the most common were for anxiety (52%), depression (40%), and PTSD/trauma (17%). There were 11% who reported using cannabis for managing other drug or alcohol use and 4% for psychosis., Conclusions: A substantial proportion of the North American population self-reported cannabis use for medical purposes for a variety of medical reasons, including those living in jurisdictions without legal markets. Further research is needed to understand the safety and efficacy of these forms of medical cannabis use., (© 2022. The Author(s).)

Rationale: Methylphenidate (MPH) and mixed D,L-amphetamine salts (MASs; Adderall) were previously found to have unreliable effects on judgment and decision processes., Objective: We predicted that MPH and MASs have a specific effect of reducing heuristic responses, which should lead to increased performance on the cognitive reflection test (CRT). The CRT is considered to be a testbed for heuristic versus deliberative response modes., Methods: We recruited a sample of 15,361 individuals using the Prolific Academic crowdsourcing platform. From this initial pool, our final sample consisted of 294 participants (125 MPH users and 169 MASs users) who conformed to the study criteria and completed the experimental tasks. Tasks were performed on days where participants were either medicated or not, allowing to assess the effect of medication status., Results: There was a strong positive effect of taking MPH on CRT scores (Cohen's d = 0.40) which was not qualified by frequency of MPH usage, ADHD symptoms, and demographic factors. There was also a somewhat weaker effect for MASs (Cohen's d = 0.07). No effects of MPH and MASs were recorded for risk-taking and numeracy., Conclusions: The results indicate that MPH enhances decision-making in tasks where heuristic responses typically bias it., (© 2021. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Rationale: Isobutyryl-carfentanyl is the most recently discovered fentanyl analogue with a chemical structure that is similar to that of carfentanyl. Its analogue, carfentanyl, is regarded as one of the most lethal drugs in the world, with a potency of 10,000 times that of morphine. Therefore, isobutyryl-carfentanyl may possess a comparably high potency and its harmful effects cannot be ignored., Objectives: This study was designed to assess the analgesic effect of isobutyryl-carfentanyl and the potential risks associated with its misuse., Methods: In this study, we assessed the acute toxicity of isobutyryl-carfentanyl by up-and-down-procedure, the analgesic efficacy by hot-plate test, the abuse potential by conditioned place preference (CPP), drug self-administration, and drug discrimination tests, and compared it with fentanyl and carfentanyl., Results: The estimated median lethal dose (LD 50 ) of isobutyryl-carfentanyl administered were 175 mg/kg (intragastric administration, IG), 15.84 mg/kg (intraperitoneal injection, IP), 15.84 mg/kg (subcutaneous injection, SC), and 1.6 mg/kg (intravenous injection, IV), respectively. The 50% maximal analgesic effect (ED 50 ) of isobutyryl-carfentanyl was determined to be 0.00319 mg/kg, with an analgesic potency 14 times that of fentanyl and 0.82 times that of carfentanyl. Isobutyryl-carfentanyl exhibited a significant positional preference at a minimum dose of 0.1 mg/kg, while fentanyl exhibited a significant positional preference at a minimum dose of 0.3 mg/kg. In the heroin (0.05 mg/kg/infusion) self-administration substitution experiment, isobutyryl-carfentanyl showed significant self-administration behaviour at doses of 0.0005-0.001 mg/kg/infusion, with the maximum number of infusions observed at a dose of 0.001 mg/kg. In the heroin (1 mg/kg) drug discrimination experiment, fentanyl (0.005-0.02 mg/kg), carfentanyl (0.0005-0.002 mg/kg), and isobutyryl-carfentanyl (0.001-0.005 mg/kg) were tested in the dose-effect curves. The results showed that all three drugs exhibit dose-dependent increase in the number of drug-associated nose pokes responses and reduction in the rate of nose pokes. The subjective effect potency of isobutyryl-carfentanyl was found to be 4.4 times that of fentanyl and 0.5 times that of carfentanyl., Conclusions: In summary, isobutyryl-carfentanyl has high acute toxicity and analgesic effect, with strong psychological dependence approximately 5 times that of fentanyl and 0.5 times that of carfentanyl, and has extremely high abuse potency., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Background: Rapid-eye movement (REM) sleep deprivation (SD) can induce manic-like behaviors in rodents. On the other hand, lithium, as one of the oldest drugs used in neuropsychiatric disorders, is still one of the best drugs for the treatment and control of bipolar disorder. In this study, we aimed to investigate the role of chronic short-term REM SD in the induction of manic-like behaviors in female rats., Methods: The rats were exposed to REM SD for 14 days (6 hours/day). Lithium was intraperitoneally injected at the doses of 10, 50, and 100 mg/kg., Results: REM SD induced hyperactivity and OCD-like behavior, and decreased anxiety, depressive-like behavior, and pain subthreshold. REM SD also impaired passive avoidance memory and decreased hippocampal brain-derived neurotrophic factor (BDNF) expression level. Lithium at the doses of 50 and 100 mg/kg partly and completely abolished these effects, respectively. However, lithium (100 mg/kg) increased BDNF expression level in control and sham REM SD rats with no significant changes in behavior., Conclusions: Chronic short-term REM SD may induce a mania-like model and lead to OCD-like behavior and irritability. In the present study, we demonstrated a putative rodent model of mania induced by chronic REM SD in female rats. We suggest that future studies should examine behavioral and mood changes following chronic REM SD in both sexes. Furthermore, the relationship between manic-like behaviors and chronic REM SD should be investigated., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Rationale: Depressed individuals demonstrate debilitating symptoms, including depressed mood, anhedonia, and effort-related deficits. Effort-related decision-making can be measured through providing subjects with a choice between high effort/reward and low effort/reward options, which is a dopamine (DA)-dependent behavior. While previous research has shown sex differences in depression rates, this has not been examined within operant-based effort-related decision-making tasks nor has DA been shown to underlie this behavior in female rats., Objectives: The current study investigated sex differences in an effort-related decision-making task prior to and following administration of the DA D2 receptor antagonist haloperidol (HAL)., Methods: Adult rats were food restricted or fed freely and trained in an effort-related progressive ratio choice task. After stable responding, HAL was administered acutely (0.05-0.2 mg/kg) prior to testing., Results: Results indicate a significant effect of sex on training variables, with males having a greater number of lever presses, higher ratios, and longer active lever times. Pretreatment with HAL significantly reduced the same measures in both sexes for the high-valued reward, while increasing chow consumption in the food restricted males. Food restricted rats showed a greater number of total lever presses and achieved higher ratios; however, the effect in male food restricted rats was greatest., Conclusions: These data suggest that, although there are sex differences in training, HAL decreases behavior across sexes, demonstrating that the D2 mechanism is similar in both sexes. These findings provide a better understanding of motivational dysfunction in both sexes and potential treatment targets for depression.

Nowadays, high morbidity and mortality of cardiovascular diseases (CVDs) and high comorbidity rate of neuropsychiatric disorders contribute to global burden of health and economics. Consequently, a discipline concerning abnormal connections between the brain and the heart and the resulting disease states, known as psychocardiology, has garnered interest among researchers. However, identifying a common pathway that physicians can modulate remains a challenge. Gut microbiota, a constituent part of the human intestinal ecosystem, is likely involved in mutual mechanism CVDs and neuropsychiatric disorder share, which could be a potential target of interventions in psychocardiology. This review aimed to discuss complex interactions from the perspectives of microbial and intestinal dysfunction, behavioral factors, and pathophysiological changes and to present possible approaches to regulating gut microbiota, both of which are future directions in psychocardiology., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Schizophrenia and autism spectrum disorder have long been associated with elevated levels of various small phenolic molecules (SPMs). In turn, the gut microbiota (GMB) has been implicated in the kinetics of many of these analytes. Unfortunately, research into the possible relevance of GMB-mediated SPMs to neuropsychiatry continues to be limited by heterogeneous study design, numerous sources of variance and technical challenges. Some SPMs have multiple structural isomers and most have conjugates. Without specialized approaches, SPMs can be incorrectly assigned or inaccurately quantified. In addition, SPM levels can be affected by dietary polyphenol or protein consumption and by various medications and diseases. Nonetheless, heterotypical excretion of various SPMs in association with schizophrenia or autism continues to be reported in independent samples. Recent studies in human cerebrospinal fluid demonstrate the presence of many SPMs A large number of these are bioactive in experimental models. Whether such mechanisms are relevant to the human brain in health or disease is not known. Systematic metabolomic and microbiome studies of well-characterized populations, an appreciation of multiple confounds, and implementation of standardized approaches across platforms and sites are needed to delineate the potential utility of the phenolic interactome in neuropsychiatry.

5-MeO-DMT is a tryptamine being developed as a potential antidepressant that may display a distinct therapeutic mechanism due to its unique pharmacology and subjective effects compared to typical psychedelics. In this article, we parallel the relatively distinct phenomenology and behavioral effects of the acute and post-acute effects of 5-MeO-DMT to those induced by epileptiform activity, particularly in instances within epileptogenic zones of the temporal lobes. This is done by reviewing aberrant 5-HT 1A receptor functioning in epilepsy, noting that 5-MeO-DMT has notable 5-HT 1A receptor agonist properties-and then comparing the acute behavioral and subjective effects induced by 5-MeO-DMT to those that occur in seizures. It might be that 5-MeO-DMT's therapeutic mechanism is partly mediated by evoking temporary epileptiform activity, suggesting a similarity to electroconvulsive therapy. It is also noted that "reactivations," the sudden re-experiencing of drug effects common after 5-MeO-DMT but not after typical psychedelics, may suggest that 5-MeO-DMT produces recurrent epileptiform activity. Overall, this review indicates that further evaluation of 5-MeO-DMT's unique mechanisms in research settings and among naturalistic users are warranted., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Rationale: Therapeutic administration of psychedelics has shown significant potential in historical accounts and recent clinical trials in the treatment of depression and other mood disorders. A recent randomized double-blind phase-IIb study demonstrated the safety and efficacy of COMP360, COMPASS Pathways' proprietary synthetic formulation of psilocybin, in participants with treatment-resistant depression., Objective: While the phase-IIb results are promising, the treatment works for a portion of the population and early prediction of outcome is a key objective as it would allow early identification of those likely to require alternative treatment., Methods: Transcripts were made from audio recordings of the psychological support session between participant and therapist 1 day post COMP360 administration. A zero-shot machine learning classifier based on the BART large language model was used to compute two-dimensional sentiment (valence and arousal) for the participant and therapist from the transcript. These scores, combined with the Emotional Breakthrough Index (EBI) and treatment arm were used to predict treatment outcome as measured by MADRS scores. (Code and data are available at https://github.com/compasspathways/Sentiment2D .) RESULTS: Two multinomial logistic regression models were fit to predict responder status at week 3 and through week 12. Cross-validation of these models resulted in 85% and 88% accuracy and AUC values of 88% and 85%., Conclusions: A machine learning algorithm using NLP and EBI accurately predicts long-term patient response, allowing rapid prognostication of personalized response to psilocybin treatment and insight into therapeutic model optimization. Further research is required to understand if language data from earlier stages in the therapeutic process hold similar predictive power., (© 2023. The Author(s).)

Rationale: In recent years, psychedelic substances with serotonergic mechanisms have accumulated substantial evidence that they may provide therapeutic benefits for people suffering with psychiatric symptoms. Psychiatric disorders targeted by these psychedelic-assisted therapies are managed with serotonergic drugs like selective serotonin reuptake inhibitors (SSRIs) as the current standard of care, so it is important to evaluate the potential risks of drug-drug interactions and serotonin toxicity (ST) between these agents., Objectives: A critical evaluation of the scientific literature is necessary to delineate the risks of ST when combining psychedelics with available serotonergic pharmacotherapy options. This review article describes signs and symptoms of ST, characterizes mechanisms of ST risk, summarizes what is known about serotonergic psychedelic drug interactions, and outlines potential management strategies., Results: True ST typically occurs with a serotonergic drug overdose or in combinations in which a drug that can increase intrasynaptic serotonin is combined with a monoamine oxidase inhibitor (MAOI). Serotonergic psychotropics that do not contain MAOIs are low risk in combination with psychedelics that also do not contain MAOIs. Signs and symptoms warranting immediate medical attention include myoclonus, extreme and fluctuating vital signs, agitation or comatose mental state, muscle rigidity, pronounced hyperthermia (fever), and/or seizure activity., Conclusions: Serotonin-related adverse reactions exist along a spectrum with serotonin syndrome being the most severe manifestations of ST. Due to varying serotonergic mechanisms of psychedelics and psychotropics, with varying propensities to increase intrasynaptic serotonin, some combinations may present a significant risk for serotonin toxicity (ST) while others are likely benign., (© 2021. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Rationale: The effects of hypnotics on automobile driving have been attracting increasing attention. However, few driving simulators (DSs) have been confirmed to have acceptable reliability and validity for assessing the next-day residual effects of zopiclone as a positive control on driving performance., Objective: To investigate whether a new DS could permit detection of the next-day residual effects of zopiclone on driving performance., Methods: In this double-blind, randomized, placebo-controlled crossover trial, 28 healthy males received zopiclone 7.5 mg at bedtime on days 1 and 8 and placebo on the other days over a period of 16 days. The participants took part in three driving tasks-road-tracking, car-following, and harsh-braking-using a DS on days 2 and 9 at 9-h post-dosing. Scores on the Karolinska Sleepiness Scale and Profile of Mood States-Second Edition were then assessed, as was the serum concentration of zopiclone., Results: The estimated differences in the standard deviation of lateral position (cm) in the road-tracking task between the zopiclone and placebo groups on days 2 and 9 were 3.75 cm (90% confidence interval (CI): 1.71-5.79) and 4.07 cm (90% CI: 2.02-6.11), respectively. The estimated differences in the distance coefficient of variation in the car-following task and in the brake reaction time in the harsh-braking task between the zopiclone and placebo groups on day 2 were 4.31 (90% CI: 1.94-6.69) and 24.6 ms (90% CI: 12.7-36.4), respectively., Conclusions: The DS used in this study has sufficient sensitivity to detect the next-day residual effects of zopiclone on driving performance., (© 2022. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Prospective memory (PM) impairment in recreational drug users has been documented in recent years. However, most studies on the effects of drugs on PM contain several methodological challenges, such as small sample size (< 100 participants), unrepresentative sample type (e.g., student or patient), short abstinence period (< 7 days), and lack of control of potential confounds (e.g., sleep and IQ). The present study investigated the possible consequences of recreational drug use on prospective memory, using self-report and lab-based prospective memory measures while overcoming the methodological challenges. The sample was composed of 47 non-users (27 females, age range from 18 to 50 +) and 53 drug users (21 females, age range from 18 to 50 +). Recreational drug users reported significantly more deficits in the long-term episodic, short-term habitual, and internally cued PM failures subscales of the Prospective Memory Questionnaire. However, these deficits were eliminated after controlling for covariates (e.g., age, sleep quality, general health, alcohol usage). Recreational drug users also performed worse than non-users in the short-term, long-term, event-based, and time-based PM subscales of the Royal Prince Alfred Prospective Memory Test. These results remained significant after controlling for the covariates. Drug users demonstrated greater impairments on time-based and long-term PM tasks thought to be linked with executive functioning. Taken together, the present study provides further support for recreational drug-related deficits in PM and highlights a dissociation between self-report and lab-based PM measures., (© 2022. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Rationale: Investigation of associated risk factors of valproic acid (VPA)-induced tremor helped in increasing tolerance and optimizing treatment scheme individually., Objectives: To determine the risk factors of VPA-induced tremor, with particular attention on identifying tremor-susceptible gene mutations., Methods: Epileptic patients taking VPA were divided into a tremor and a non-tremor groups. A mutation of rs9652490 in the leucine-rich repeat and immunoglobulin domain-containing Nogo-receptor-interacting protein 1 (LINGO-1) gene was determined by Sanger sequencing. Cerebellar atrophy was assessed, and various cerebellar dimensions were measured on magnetic resonance imaging (MRI) scans., Results: One hundred and eighty-one of 200 subjects were included. Multivariate regression analysis indicated several VPA-induced tremor-related factors: females (OR = 2.718, p = 0.014), family history of tremor (OR = 7.595, p = 0.003), treatment duration (> 24 months; OR = 3.294, p = 0.002), and daily dosage (> 1,000 mg/d; OR = 19.801, p = 0.008) of VPA. Chi-square tests revealed that treatment with VPA magnesium-ER (p = 0.030) and carbamazepine combination (p = 0.040) reduced the incidence of tremor. One hundred and seventy-six gene sequencing and 86 MRI results excluded any significant difference between the two groups in the mutation of rs9652490 within LINGO-1, the ratio of cerebellar atrophy or the cerebellar-dimension values (p > 0.05). However, mutation of rs9652490 within LINGO-1 was correlated with increased cerebellar atrophy (p = 0.001), reduced cerebellar hemisphere thickness (p = 0.025), and right cerebellar hemisphere longitudinal diameter (p = 0.047)., Conclusions: Our cohort indicated risk (female, positive family history of tremor, daily dosage > 1000 mg and treatment duration > 24 months of VPA) and protective factors (VPA magnesium-ER and combination with CBZ) of VPA-induced tremor. Mutation of rs9652490 within LINGO-1 correlated with cerebellar atrophy, neither was correlated with VPA-induced tremor., (© 2021. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

The importance of integrative biobehavioral responses to complex challenges cannot be overlooked. In this study, the synergetic effects of icariin (a flavonoid present in the plant Epimedium brevicornum), natural enrichment (NaEn), and play behavior were investigated. Rats (n = 60) were assigned to standard housing or NaEn; these two groups were subsequently divided into controls, rats receiving icariin treatments, and rats receiving icariin and allowed to play with an individual from another cage. All rats were exposed to unpredictable mild stressors for 4 weeks. At the end of the treatment, a Forced Swim Task (FST) was conducted to assess emotional regulation during an inescapable acute challenge. Biological samples were collected weekly and before and after the FST to monitor endocrine changes. Corticosterone (CORT), dehydroepiandrosterone (DHEA), and testosterone (T) were assayed. We found that icariin had a significant effect on DHEA/CORT ratios and T levels. NaEn also had a significant effect on both CORT and DHEA, but not on T levels. Play did not appear to be significantly related to the endocrine changes. The strongest positive effects on emotional resilience were observed in NaEn rats that also received icariin. Our results confirmed that using multiple channels to stimulate adaptive responses can be effective in increasing the ability of an organism to face uncertainty. Considering how quickly our life can change due to unpredictable events, our data is instrumental to a better comprehension of the many aspects of integrative biobehavioral responses., (© 2021. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Background: The use of sedatives or hypnotics and the recurrence of depression have not been adequately explored. This study investigated the roles of sedative-hypnotics in patients with major depressive disorder (MDD). Various characteristics of sedative-hypnotic use were tested as risk factors for recurrence., Methods: Clinical records of 15,510 patients with major depressive disorder who prescribed selective serotonin reuptake inhibitors (SSR) during 1997-2009 were collected from the National Health Insurance Research Database (NHIRD). Cox proportional hazard regression models were used to analyze factors related to depression recurrence., Results: The risk of MDD recurrence was lower for patients using SED/HYP with an indication of both anxiolytics and hypnotics (AHR = 0.66; 95% CI = 0.59-0.72) than for those using SED/HYP with an indication of anxiolytics only. AHR was slightly greater in current users than in recent users (AHR = 0.77; 95% CI = 0.72-0.83) and past users (AHR = 0.70; 95% CI = 0.67-0.74). There was a higher AHR of MDD recurrence in patients who used SED/HYP over 1 DDD in 1 month than those who used SED/HYP less than 1 DDD in 1 month, with the highest-dose users having the highest risk of MDD recurrence (AHR = 7.91; 95% CI = 6.86-9.11)., Conclusions: Patterns and characteristics of sedative-hypnotic use may affect depression recurrence. These findings should be considered by clinicians when combining sedative-hypnotics with antidepressant treatment.

Rationale: Memory plays a central role in the psychedelic experience. The spontaneous recall and immersive reliving of autobiographical memories has frequently been noted by researchers and clinicians as a salient phenomenon in the profile of subjective effects of classic psychedelic drugs such as psilocybin, LSD, and ayahuasca. The ability for psychedelics to provoke vivid memories has been considered important to their clinical efficacy., Objective: This review aims to examine and aggregate the findings from experimental, observational, and qualitative studies on the acute modulation of memory by classic psychedelics in humans., Method: A literature search was conducted using PubMed and PsycInfo as well as manual review of references from eligible studies. Publications reporting quantitative and/or qualitative findings were included; animal studies and case reports were excluded., Results: Classic psychedelics produce dose-dependently increasing impairments in memory task performance, such that low doses produce no impairment and higher doses produce increasing levels of impairment. This pattern has been observed in tasks assessing spatial and verbal working memory, semantic memory, and non-autobiographical episodic memory. Such impairments may be less pronounced among experienced psychedelic users. Classic psychedelics also increase the vividness of autobiographical memories and frequently stimulate the recall and/or re-experiencing of autobiographical memories, often memories that are affectively intense (positively or negatively valenced) and that had been avoided and/or forgotten prior to the experience., Conclusions: Classic psychedelics dose-dependently impair memory task performance but may enhance autobiographical memory. These findings are relevant to the understanding of psychological mechanisms of action of psychedelic-assisted psychotherapy.

Rationale: Risky choice can be measured using the risky decision task (RDT). In the RDT, animals choose between a large, risky option that is paired with probabilistic foot shock and a small, safe option that is never paired with shock. To date, studies examining the neurochemical basis of decision-making in the RDT have focused primarily on the dopaminergic system but have not focused on the glutamatergic system, which has been implicated in risky decision-making., Objectives: Because glutamate is known to play a critical role in decision-making, we wanted to determine the contribution of the glutamatergic system to performance in the RDT., Methods: In the experiment, 32 rats (16 male; 16 female) were tested in the RDT. The probability of receiving a foot shock increased across the session (ascending schedule) for half of the rats but decreased across the session (descending schedule) for half of the rats. Following training, rats received injections of the N-methyl-D-aspartate (NMDA) receptor competitive antagonist CGS 19755 (0, 1.0, 2.5, 5.0 mg/kg; s.c.) and the GluN2B-selective antagonist Ro 63-1908 (0, 0.1, 0.3, 1.0 mg/kg; s.c.)., Results: CGS 19755 (2.5 and 5.0 mg/kg) increased risky choice in males and females trained on the ascending schedule. Ro 63-1908 (1.0 mg/kg) decreased risky choice, but only in male rats trained on the ascending schedule., Conclusions: Although NMDA receptor antagonists differentially alter risky choice in the RDT, the current results show that NMDA receptors are an important mediator of decision-making involving probabilistic delivery of positive punishment.

Trust is central to bonding and cooperation. In many social interactions, individuals need to trust another person exclusively on the basis of their subjective impressions of the other's trustworthiness. Such impressions can be formed from social information from faces (e.g., facial trustworthiness and attractiveness) and guide trusting behaviors via activations of dopaminergic brain regions. However, the specific dopaminergic effects on impression-based trust are to date elusive. Here, in a double-blind, placebo-controlled, within-subject design, we administrated a D2/D3 dopamine agonist (pramipexole) to 28 healthy females who subsequently played a one-shot trust game with partners of varying facial trustworthiness. Our results show that by minimizing facial attractiveness information, we could isolate the specific effects of facial trustworthiness on trust in unknown partners. Despite no modulation of trustworthiness impressions, pramipexole intake significantly impacted trusting behaviors. Notably, these effects of pramipexole on trusting behaviors interacted with participants' hormonal contraceptive use. In particular, after pramipexole intake, trust significantly decreased in hormonal contraceptive non-users. This study fills an important gap in the experimental literature on trust and its neural dynamics, unearthing the cognitive and neural modulations of trusting behaviors based on trustworthiness impressions of others.

Rationale: Multiple drugs are known to induce metabolic malfunctions, among them second-generation antipsychotics (SGAs). The pathogenesis of such adverse effects is of multifactorial origin., Objectives: We investigated whether SGAs drive dysbiosis, assessed whether gut microbiota alterations affect body weight and metabolic outcomes, and looked for the possible mechanism of metabolic disturbances secondary to SGA treatment in animal and human studies., Methods: A systematic literature search (PubMed/Medline/Embase/ClinicalTrials.gov/PsychInfo) was conducted from database inception until 03 July 2018 for studies that reported the microbiome and weight alterations in SGA-treated subjects., Results: Seven articles reporting studies in mice (experiments = 8) and rats (experiments = 3) were included. Olanzapine was used in five and risperidone in six experiments. Only three articles (experiments = 4) in humans fit our criteria of using risperidone and mixed SGAs. The results confirmed microbiome alterations directly (rodent experiments = 5, human experiments = 4) or indirectly (rodent experiments = 4) with predominantly increased Firmicutes abundance relative to Bacteroidetes, as well as weight gain in rodents (experiments = 8) and humans (experiments = 4). Additionally, olanzapine administration was found to induce both metabolic alterations (adiposity, lipogenesis, plasma free fatty acid, and acetate levels increase) (experiments = 3) and inflammation (experiments = 2) in rodents, whereas risperidone suppressed the resting metabolic rate in rodents (experiments = 5) and elevated fasting blood glucose, triglycerides, LDL, hs-CRP, antioxidant superoxide dismutase, and HOMA-IR in humans (experiment = 1). One rodent study suggested a gender-dependent effect of dysbiosis on body weight., Conclusions: Antipsychotic treatment-related microbiome alterations potentially result in body weight gain and metabolic disturbances. Inflammation and resting metabolic rate suppression seem to play crucial roles in the development of metabolic disorders.

Rationale: The endocannabinoid system (ECS) belongs to the G protein-coupled receptor family of cell membranes and is associated with neuropsychiatric conditions, and neurodegenerative diseases. Cannabinoid 2 receptors (CB2) are expressed in the central nervous system (CNS) on microglia and subgroups of neurons and are involved in various behavioural processes via immunological and neural regulation., Objective: The objective of this paper is to summarize and explore the impact of CB2 receptors on neuronal modulation, their involvement in various neurological disorders, and their influence on mood, behavior, and cognitive function., Results: The activation of CB2 appears to protect the brain and its functions from damage under neuroinflammatory actions, making it an attractive target in a variety of neurological conditions such as Parkinson's disease (PD), multiple sclerosis (MS), Alzheimer's disease (AD), and Huntington's disease (HD). During inflammation, there is an overexpression of CB2 receptors, and CB2 agonists show a strong anti-inflammatory effect. These results have sparked interest in the CB2 receptors as a potential target for neurodegenerative and neuroinflammatory disease treatment., Conclusion: In conclusion, CB2 receptors signalling shows promise for developing targeted interventions that could positively affect both immune and neuronal functions, ultimately influencing behavioral outcomes in both health and disease., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Cannabis and its major constituents, Δ 9 -tetrahydrocannabinol (THC) and cannabidiol (CBD), are being widely used to treat sleep disturbances. However, THC can cause acute cognitive and psychomotor impairment and there are concerns that driving and workplace safety might be compromised the day after evening use. Here, we examined possible 'next day' impairment following evening administration of a typical medicinal cannabis oil in adults with insomnia disorder, compared to matched placebo. This paper describes the secondary outcomes of a larger study investigating the effects of THC/CBD on insomnia disorder. Twenty adults [16 female; mean (SD) age, 46.1 (8.6) y] with physician-diagnosed insomnia who infrequently use cannabis completed two 24 h in-laboratory visits involving acute oral administration of combined 10 mg THC and 200 mg CBD ('THC/CBD') or placebo in a randomised, double-blind, crossover trial design. Outcome measures included 'next day' (≥9 h post-treatment) performance on cognitive and psychomotor function tasks, simulated driving performance, subjective drug effects, and mood. We found no differences in 'next day' performance on 27 out of 28 tests of cognitive and psychomotor function and simulated driving performance relative to placebo. THC/CBD produced a small decrease (-1.4%, p=.016, d=-0.6) in accuracy on the Stroop-Colour Task (easy/congruent) but not the Stroop-Word Task (hard/incongruent). THC/CBD also produced a small increase (+8.6, p=.042, d=0.3) in self-ratings of Sedated at 10 h post-treatment, but with no accompanying changes in subjective ratings of Alert or Sleepy (p's>0.05). In conclusion, we found a lack of notable 'next day' impairment to cognitive and psychomotor function and simulated driving performance following evening use of 10 mg oral THC, in combination with 200 mg CBD, in an insomnia population who infrequently use cannabis., (© 2024. The Author(s).)

Rationale: Psychedelic-assisted psychotherapy (PAP) has emerged as a potential treatment for a variety of mental health conditions, including substance use disorders and depression. Current models of PAP emphasize the importance of psychotherapeutic support before, during, and after ingestion of a psychedelic to maximize safety and clinical benefit. Despite this ubiquitous assumption, there has been surprisingly little empirical investigation of the "psychotherapy" in PAP, leaving critical questions about the necessary and sufficient components of PAP unanswered., Objectives: As clinical trials for psychedelic compounds continue the transition from safety- and feasibility-testing to evaluating efficacy, the role of the accompanying psychotherapy must be better understood to enhance scientific understanding of the mechanisms underlying therapeutic change, optimize clinical outcomes, and inform cost-effectiveness., Results: The present paper first reviews the current status of psychotherapy in the PAP literature, starting with recent debates regarding "psychotherapy" versus "psychological support" and then overviewing published clinical trial psychotherapy models and putative models informed by theory. We then delineate lessons that PAP researchers can leverage from traditional psychotherapy research regarding standardizing treatments (e.g., publish treatment manuals, establish eligibility criteria for providers), identifying mechanisms of change (e.g., measure established mechanisms in psychotherapy), and optimizing clinical trial designs (e.g., consider dismantling studies, comparative efficacy trials, and cross-lagged panel designs). Throughout this review, the need for increased research into the psychotherapeutic components of treatment in PAP is underscored., Conclusions: PAP is a distinct, integrative, and transdisciplinary intervention. Future research designs should consider transdisciplinary research methodologies to identify best practices and inform federal guidelines for PAP administration., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Aim: Much research has been conducted on the acute effects of nicotine on human cognitive performance, demonstrating both enhancing and impairing cognitive effects. With the relatively recent introduction of electronic cigarettes ('e-cigarettes') as a smoking cessation device, little is known about the cognitive effects of e-cigarettes specifically, either as a nicotine replacement device or in the absence of nicotine. The purpose of this review was to present an overview of evidence from empirical studies on the effect of e-cigarettes on cognitive function., Approach: Guided by Preferred Reporting Items for Systematic Reviews and Meta-Analyses for Scoping Reviews guidelines (PRISMA-ScR), SCOPUS, PubMed, and EBSCOhost were searched from 2006, the year e-cigarettes were introduced, to June 2023 for relevant papers, along with reference lists checked for additional papers., Key Findings: Seven experimental and four cross-sectional survey studies were identified and included. The majority of the studies only include regular and current cigarette smokers and primarily assessed the acute cognitive effect of e-cigarettes relative to nicotine. While the findings primarily suggest either no or positive effect of e-cigarettes on cognition in cigarette smokers, associations between e-cigarettes and cognitive impairments in memory, concentration and decision making were reported in both cigarette smokers and never-smokers., Implications and Conclusions: The acute cognitive effect of e-cigarettes on regular cigarette smokers appears minimal. However, long-term cognitive effect and their effects on never-smokers are unclear. Given that the increased numbers of e-cigarette users are non-smokers and/or adolescents, research with those naïve to nicotine and a developmentally vulnerable adolescent population on its long-term effect is needed., (© 2024. The Author(s).)

Opioid use results in thousands of overdose deaths each year. To address this crisis, we need a better understanding of the neurobiological mechanisms that drive opioid abuse. The noninvasive imaging tools positron emission tomography (PET), functional magnetic resonance imaging (fMRI), and manganese-enhanced magnetic resonance imaging (MEMRI) can be used to identify how brain activity responds to acute opioid exposure and adapts to chronic drug treatment. These techniques can be performed in humans and animal models, and brain networks identified in animals closely map to the human brain. Animal models have the advantage of being able to systematically examine the independent effects of opioid exposure in a controlled environment accounting for the complex factors that drive opioid misuse in humans. This review synthesizes literature that utilized noninvasive neuroimaging tools (PET, fMRI, and MEMRI) measuring brain activity correlates in animals to understand the neurobiological consequences of exposure to abused opioids. A PubMed search in September 2023 identified 25 publications. These manuscripts were divided into 4 categories based on the route and duration of drug exposure (acute/chronic, active/passive administration). Within each category, the results were generally consistent across drug and imaging protocols. These papers cover a 20-year range and highlight the advancements in neuroimaging methodology during that time. These advances have enabled researchers to achieve greater resolution of brain regions altered by opioid exposure and to identify patterns of brain activation across regions (i.e., functional connectivity) and within subregions of structures. After describing the existing literature, we suggest areas where additional research is needed., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Since the second half of the twentieth century, many important discoveries in the field of behavioral psychopharmacology have been made using operant conditioning cages. These cages provide objective data collection and have revolutionized behavioral research. Unfortunately, in the rush towards automation, many mistakes may have been made that could have been avoided by observing experimental animals. The study described in this paper is an excellent example of how important additional behavioral observation can be for interpreting instrumental data. In this study, we evaluated the effects of single injections of 3 different doses of agomelatine (5, 10, and 40 mg/kg) on feedback sensitivity in rats. To this end, we tested 40 animals in the instrumental probabilistic reversal learning task in a Latin square design. The highest applied dose of agomelatine, prima facie, reduced the sensitivity of rats to negative feedback - an effect that can be considered antidepressant. However, additional behavioral observation dramatically changed the interpretation of the results and revealed that the perceived effect of agomelatine on sensitivity to negative feedback can actually be attributed to drug-induced drowsiness., (© 2023. The Author(s).)

Rationale: Challenges in drug development for psychiatric disorders have left much room for the introduction of novel treatments with better therapeutic efficacies and indices. As a result, intense research has focused on identifying new targets for developing such pharmacotherapies. One of these targets may be the phosphodiesterase (PDE) class of enzymes, which play important roles in intracellular signaling. Due to their critical roles in cellular pathways, these enzymes affect diverse neurobiological functions from learning and memory formation to neuroinflammation., Objectives: In this paper, we reviewed studies on the use of PDE inhibitors (PDEIs) in preclinical models and clinical trials of psychiatric disorders including depression, anxiety, schizophrenia, post-traumatic stress disorder (PTSD), bipolar disorder (BP), sexual dysfunction, and feeding disorders., Results: PDEIs are able to improve symptoms of psychiatric disorders in preclinical models through activating the cAMP-PKA-CREB and cGMP-PKG pathways, attenuating neuroinflammation and oxidative stress, and stimulating neural plasticity. The most promising therapeutic candidates to emerge from these preclinical studies are PDE2 and PDE4 inhibitors for depression and anxiety and PDE1 and PDE10 inhibitors for schizophrenia. Furthermore, PDE3 and 4 inhibitors have shown promising results in clinical trials in patients with depression and schizophrenia., Conclusions: Larger and better designed clinical studies of PDEIs in schizophrenia, depression, and anxiety are warranted to facilitate their translation into the clinic. Regarding the other conditions discussed in this review (most notably PTSD and BP), better characterization of the effects of PDEIs in preclinical models is required before clinical studies., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Rationale: Drug and natural rewarding stimuli activate the mesolimbic dopaminergic system. Both methamphetamine (Meth) and copulation to satiety importantly increase dopamine (DA) release in the nucleus accumbens (NAc), but with differences in magnitude. This paper analyzes the interaction between Meth administration and the intense sexual activity associated with sexual satiety., Objectives: To evaluate possible changes in Meth-induced behavioral effects and striatal DA-related protein expression due to sexual satiety., Methods: Meth-induced locomotor activity and conditioned place preference (CPP) were tested in sexually experienced male rats that copulated to satiety (S-S) or ejaculated once (1E) the day before or displayed no sexual activity (control group; C). DA receptors and DA transporter expression were determined by western blot in the striatum of animals of all sexual conditions treated with specific Meth doses., Results: Meth's locomotor and rewarding effects were exacerbated in S-S animals, while in 1E rats, only locomotor effects were enhanced. Sexual activity, by itself, modified DA-related protein expression in the NAc core and in the caudate-putamen (CPu), while Meth treatment alone changed their expression only in the NAc shell. Meth-induced changes in the NAc shell turned in the opposite direction when animals had sexual activity, and additional changes appeared in the NAc core and CPu of S-S rats., Conclusion: Sexual satiety sensitizes rats to Meth's behavioral effects and the Meth-induced striatal DA-related protein adaptations are modified by sexual activity, evidencing cross-sensitization between both stimuli., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Rationale: The use of psychedelics for medical and recreational purposes is rising. Contextual factors such as expectancy, intention, and sensory and social environment (set and setting) are widely recognized as moderating the effects of these substances. Nevertheless, clinical trials of microdosing - the ingestion of small, sub-hallucinogenic doses of psychedelics - rarely report their set and setting. This fact suggests that such factors are not considered important in the context of microdosing., Objective: This paper challenges this assumption and makes the case for the crucial relevance of set and setting in microdosing practice. Building on set and setting theory and placebo theory, we explain why set and setting are of crucial importance in the case of microdosing., Results: This reasoning helps elucidate the role of set and setting in determining the outcomes of microdosing and helps explain some of the contradictory results that have emerged in microdosing research in recent years., Conclusion: Set and setting are important constructs to be considered especially in the context of microdosing psychedelics. By reporting set and setting, the results of microdosing research can be made more reliable and consistent., (© 2022. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Rationale: Current pharmacological approaches to treatment of post-traumatic stress disorder (PTSD) lack adequate effectiveness. As a result, identifying new molecular targets for drug development is necessary. Furthermore, fear learning and memory in PTSD can undergo different phases, such as fear acquisition, consolidation, and extinction. Each phase may involve different cellular pathways and brain regions. As a result, effective management of PTSD requires mindfulness of the timing of drug administration. One of the molecular targets currently under intense investigation is the N-methyl-D-aspartate (NMDA)-type glutamate receptor (NMDAR). However, despite the therapeutic efficacy of drugs targeting NMDAR, their translation into clinical use has been challenging due to their various side effects. One possible solution to this problem is to target signaling proteins downstream to NMDAR to improve targeting specificity. One of these proteins is the neuronal nitric oxide synthase (nNOS), which is activated following calcium influx through the NMDAR., Objective: In this paper, we review the literature on the pharmacological modulation of nNOS in animal models of PTSD to evaluate its therapeutic potential. Furthermore, we attempt to decipher the inconsistencies observed between the findings of these studies based on the specific phase of fear learning which they had targeted., Results: Inhibition of nNOS may inhibit fear acquisition and recall, while not having a significant effect on fear consolidation and extinction. However, it may improve extinction consolidation or reconsolidation blockade., Conclusions: Modulation of nNOS has therapeutic potential against PTSD and warrants further development for use in the clinical setting., (© 2022. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Rationale: Ketamine has rapid antidepressant effects that represent a significant advance in treating depression, but its poor safety and tolerability limit its clinical utility. Accreting evidence suggests that serotonergic neurotransmission participates in the rapid antidepressant effects of ketamine and hallucinogens. Thus, understanding how serotonin contributes to these effects may allow identification of novel rapid antidepressant mechanisms with improved tolerability., Objective: The goal of this paper is to understand how serotonergic mechanisms participate in rapid antidepressant mechanisms., Methods: We review the relevance of serotonergic neurotransmission for rapid antidepressant effects and evaluate the role of 5-HT 1A , 5-HT 1B , 5-HT 2A , and 5-HT 4 receptors in synaptic plasticity, BDNF signaling, and GSK-3β activity. Subsequently, we develop hypotheses on the relationship of these receptor systems to rapid antidepressant effects., Results: We found that 5-HT 1A and 5-HT 1B receptors may participate in ketamine's rapid antidepressant mechanisms, while agonists at 5-HT 2A and 5-HT 4 receptors may independently behave as rapid antidepressants. 5-HT 1A , 5-HT 2A , and 5-HT 4 receptors increase synaptic plasticity in the cortex or hippocampus but do not consistently increase BDNF signaling. We found that 5-HT 1A and 5-HT 1B receptors may participate in rapid antidepressant mechanisms as a consequence of increased BDNF signaling, rather than a cause. 5-HT 2A and 5-HT 4 receptor agonists may increase BDNF signaling, but these relationships are tenuous and need more study. Finally, we found that ketamine and several serotonergic receptor systems may mechanistically converge on reduced GSK-3β activity., Conclusions: We find it plausible that serotonergic neurotransmission participates in rapid antidepressant mechanisms by increasing synaptic plasticity, perhaps through GSK-3β inhibition., (© 2022. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

The therapeutic potential of medical cannabis to treat a variety of conditions is becoming increasingly recognised. Globally, a large number of countries have now legalised cannabis for medical uses and a substantial number of patients are able to access their medications. Yet in the UK, where medical cannabis was legalised in November 2018, only a handful of NHS prescriptions have been written, meaning that most patients are unable to access the medicine. Reasons for this are manyfold and include the perceived lack of clinical evidence due to the challenges of studying medical cannabis through randomised controlled trials. In order to develop the current evidence base, the importance of incorporating real-world data (RWD) to assess the effectiveness and efficacy of medical cannabis has gradually become recognised. The current paper provides a detailed outline of Project Twenty21 (T21), the UK's first medical cannabis registry, launched in August 2020. We provide the rationale for T21 and describe the methodology before reporting the characteristics of the 'first patients' enrolled in the registry. We describe the health status of all patients enrolled into the project during its first 7 months of operation and the sociodemographic characteristics and primary presenting conditions for these patients, as well as details of the medical cannabis prescribed to these individuals. By 12th March 2021, 678 people had been enrolled into T21; the majority (64%) were male and their average age was 38.7 years (range = 18-80). The most commonly reported primary conditions were chronic pain (55.6%) and anxiety disorders (32.0%) and they reported high levels of multi-morbidity, including high rates of insomnia and depression. We also present preliminary evidence from 75 patients followed up after 3 months indicating that receipt of legal, prescribed cannabis was associated with a significant increase in self-reported health, assessed using the visual analogue scale of the EQ-5D-5L (Cohen's d = .77, 95% CI = .51-1.03). Our initial findings complement reports from other large-scale databases globally, indicating that the current RWD is building up a pattern of evidence. With many clinicians demanding better and faster evidence to inform their decisions around prescribing medical cannabis, the current and future results of T21 will expand the existing evidence base on the effectiveness of cannabis-based medical products (CBMPs)., (© 2021. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

The potential of mitragynine to produce physiological dependence (withdrawal) was assessed using a rapid assessment procedure with male ICR mice exposed to heroin-admixed food followed by naloxone (subcutaneously, s.c.) precipitation of withdrawal. Initial studies indicated that 3 days of exposure to 3.0 mg/g of heroin-admixed food followed by naloxone (0.6 mg/kg) reliably precipitated withdrawal jumping and weight loss. Lower concentrations of heroin-admixed food and lower doses of naloxone produced fewer withdrawal signs. A longer exposure to heroin-admixed food did not produce significantly greater amounts of jumping or weight loss. Further, these withdrawal signs were dose-dependently reversed by s.c. administration of heroin immediately following naloxone administration. Mitragynine (s.c.) also dose-dependently suppressed naloxone-precipitated withdrawal signs. Additionally, both jumping and weight loss were suppressed over a comparable range of mitragynine doses when administered by gavage with a noticeably, but not significantly, higher potency than with s.c. administration. The ED 50 values for mitragynine for the suppression of withdrawal by any route (354-911 μmol/kg) were greater than the minimally effective dose that decreased locomotor activity (251 μmol/kg) and from 40- to 104-fold greater than those for heroin. The results suggest inherent opioid dependence liability of mitragynine. The in vivo potency relations between mitragynine and heroin are consistent with a conclusion of dependence-producing effects, indicated by the suppression of withdrawal, comparable to standard opioid μ-receptor agonists, differing primarily in terms of potency. The present paper provides a method for the rapid assessment of physiological dependence liability applicable to other kratom plant constituents or any potential opioid dependence-producing agents., (© 2022. This is a U.S. government work and not under copyright protection in the U.S.; foreign copyright protection may apply.)

Rationale: Psychostimulants, including methylphenidate (MPH), are the mainstay of pharmacotherapy for attention-deficit/hyperactivity disorder (ADHD) in adults. Even though MPH is the most commonly used medication for ADHD these days, there are relatively few resources available that provide comprehensive insight into the pharmacological and clinical features of the compound., Objective: The aim of this paper is to provide an up-to-date outline of the pharmacology and clinical utility of MPH for ADHD in adult patients., Methods: While conducting the narrative review, we applied structured search strategies covering the two major online databases (MEDLINE and Cochrane Central Register of Controlled Trials). In addition, we performed handsearching of reference lists of relevant papers., Results: Methylphenidate exhibits multimodal mechanism of action, working primarily as a dopamine and noradrenaline reuptake inhibitor. It also protects the dopaminergic system against the ongoing 'wearing off' (by securing a substantial reserve pool of the neurotransmitter, stored in the presynaptic vesicles). In placebo-controlled trials, MPH was shown to be moderately effective both against the core ADHD symptoms (standardized mean difference [SMD], 0.49; 95% confidence interval [CI], 0.35-0.64), and the accompanying emotion regulation deficits (SMD, 0.34; 95% CI, 0.23-0.45). The most common adverse events related to long-term treatment with MPH are decreased appetite (~ 20%), dry mouth (15%), heart palpitations (13%), gastrointestinal infections (~ 10%), and agitation/feeling restless (~ 10%)., Conclusions: There is substantial body of evidence to suggest that MPH is an effective and safe treatment option for adults with ADHD., (© 2021. The Author(s).)

Depression is a leading cause of disability worldwide and improving its treatment is a core research priority for future programmes. A change in the view of psychological and biological processes, from seeing them as separate to complementing one another, has introduced new perspectives on pathological mechanisms of depression and treatment mode of action. This review presents a theoretical model that incorporated this novel approach, the cognitive neuropsychological hypothesis of antidepressant action. This model proposes that antidepressant treatments decrease the negative bias in the processing of emotionally salient information early in the course of antidepressant treatment, which leads to the clinically significant mood improvement later in treatment. The paper discusses the role of negative affective biases in the development of depression and response to antidepressant treatments. It also discusses whether the model can be applied to other antidepressant interventions and its potential translational value, including treatment choice, prediction of response and drug development.

Rationale: Cannabidiol (CBD) products lacking regulatory approval are being used to self-treat a myriad of conditions and for their unsubstantiated health benefits. The scientific evidence supporting these claims largely arises not from controlled clinical trials, but from the recognition that CBD has numerous biological targets. Yet, CBD is commonly consumed and often in over-the-counter products that are unapproved and of unknown composition. Epidiolex® is the only product that has undergone rigorous pharmacokinetic assessment and testing in clinical trials; it was approved as a non-scheduled drug by the U.S. Food and Drug Administration for the treatment of intractable childhood-onset seizures. However, studies investigating CBD for other medical conditions are limited in number and often lack the scientific rigor, controls, or sample sizes required to draw clinically meaningful conclusions. Although Epidiolex® is safe for human consumption, recent changes in regulation of commercially available CBD products have resulted in limited quality control and products marketed with unknown CBD bioavailability. Even scientifically rigorous studies have used different sources of CBD and different suspension vehicles for administration, making it difficult to compare results among studies and resolve mixed outcomes., Objectives: This paper reviews the molecular targets, pharmacokinetics, and safety and abuse liability of CBD; additionally, the extant evidence on its potential therapeutic effects for neurological disorders, pain, inflammation, conditions related to immune function, psychiatric disorders, and substance use are described.

Ayahuasca is a psychoactive plant brew containing dimethyltryptamine (DMT) and monoamine oxidase inhibitors (MAOIs). It originates from the Amazon basin, where it is used primarily for ceremonial purposes. Ayahuasca tourists are now entering certain communities seeking alternative physical or psychological healing, as well as spiritual growth., Rationale: Recent evidence has shown that the similar acting psychedelic compound, psilocybin, facilitated long-term increases in trait openness following a single administration., Objectives: This paper assesses the impact of ayahuasca on personality in a traditional framework catering for ayahuasca tourists., Method: Within a mixed design, we examined the effect of ayahuasca on participants' personality (measured by the NEO Personality Inventory 3 questionnaire) across time (pre- to post-ayahuasca administration, and 6-month follow-up), relative to a comparison group (who did not ingest ayahuasca)., Results: The results demonstrated significant increases in agreeableness pre- and post-ayahuasca administration and significant reductions in neuroticism in 24 participants, relative to the comparison group. Both of these changes were sustained at 6-month follow-up, and trait level increases were also observed in openness at this stage. Additionally, greater perceived mystical experience (measured using the Mystical Experience Questionnaire 30) was associated with increased reductions in neuroticism., Conclusions: These findings, which indicate a positive mediating effect of ayahuasca on personality, support the growing literature suggesting potential therapeutic avenues for serotonergic psychedelics.

Rationale: Schizophrenia is a mental illness which is characterised by positive and negative symptoms and by cognitive impairments. While the major prevailing hypothesis is that altered dopaminergic and/or glutamatergic transmission contributes to this disease, there is evidence that the noradrenergic system also plays a role in its major symptoms., Objectives: In the present paper, we investigated the pro-cognitive effect of 1-methyl-1,2,3,4-tetrahydroisoquinoline (1MeTIQ) an endogenous neuroprotective compound, on ketamine-modelled schizophrenia in rats., Methods: We used an antagonist of NMDA receptors (ketamine) to model memory deficit symptoms in rats. Using the novel object recognition (NOR) test, we investigated the pro-cognitive effect of 1MeTIQ. Additionally, olanzapine, an atypical antipsychotic drug, was used as a standard to compare the pro-cognitive effects of the substances. In vivo microdialysis studies allowed us to verify the changes in the release of monoamines and their metabolites in the rat striatum., Results: Our study demonstrated that 1MeTIQ, similarly to olanzapine, exhibits a pro-cognitive effect in NOR test and enhances memory disturbed by ketamine treatment. Additionally, in vivo microdialysis studies have shown that ketamine powerfully increased noradrenaline release in the rat striatum, while 1MeTIQ and olanzapine completely antagonised this neurochemical effect., Conclusions: 1MeTIQ, as a possible pro-cognitive drug, in contrast to olanzapine, expresses beneficial neuroprotective activity in the brain, increasing concentration of the extraneuronal dopamine metabolite, 3-methoxytyramine (3-MT), which plays an important physiological role in the brain as an inhibitory regulator of catecholaminergic activity. Moreover, we first demonstrated the essential role of noradrenaline release in memory disturbances observed in the ketamine-model of schizophrenia, and its possible participation in negative symptoms of the schizophrenia.

Rationale: The regular consumption of very small doses of psychedelic drugs (known as microdosing) has been a source of growing media and community attention in recent years. However, there is currently limited clinical and social research evidence on the potential role of microdosing as therapies for mental and substance use disorders., Objectives: This paper examined subjective experiences of microdosing psychedelics to improve mental health or to cease or reduce substance use, and examined sociodemographic and other covariates of perceived improvements in mental health that individuals attributed to microdosing., Methods: An international online survey was conducted in 2018 and examined people's experiences of using psychedelics for self-reported therapeutic or enhancement purposes. This paper focuses on 1102 respondents who reported current or past experience of psychedelic microdosing., Results: Twenty-one percent of respondents reported primarily microdosing as a therapy for depression, 7% for anxiety, 9% for other mental disorders and 2% for substance use cessation or reduction. Forty-four percent of respondents perceived that their mental health was "much better" as a consequence of microdosing. In a multivariate analysis, perceived improvements in mental health from microdosing were associated with a range of variables including gender, education, microdosing duration and motivations, and recent use of larger psychedelic doses., Conclusions: Given the promising findings of clinical trials of standard psychedelic doses as mental health therapies, clinical microdosing research is needed to determine its potential role in psychiatric treatment, and ongoing social research to better understand the use of microdosing as self-managed mental health and substance use therapies.

The incorporation of microeconomics concepts into studies using self-administration procedures has provided critical insights into the factors that influence consumption of a wide range of food and drug reinforcers. In particular, the fitting of demand curves to consumption data provides a powerful analytic tool for computing objective metrics of behavior that can be compared across a wide range of reward types in both human and animal experiments. The results of these analyses depend crucially on the mathematical form used to fit the data. The most common choice is an exponential form proposed by Hursh and Silberberg, which is widely used and has provided fundamental insights into relationships between cost and consumption, but it also has some disadvantages. In this paper, we first briefly review the use of demand curves to quantify the motivating effects of food and drugs, then we describe the current methodology and highlight some potential issues that arise in its application. To address these issues, we propose a new mathematical framework for the analysis of consumption data, including a new functional form for the demand curve. We show that this proposed form gives good fits to data for a range of different reinforcers and experimental protocols, while allowing for straightforward calculation of key metrics of demand, including preferred consumption level, maximum response, price at maximum response, and price elasticity of demand. We provide software implementing our entire analysis pipeline, including data fits, data visualization, and the calculation of demand metrics.

Research has shown that psychedelics, such as lysergic acid diethylamide (LSD), have profound anti-inflammatory properties mediated by 5-HT 2A receptor signaling, supporting their evaluation as a therapeutic for neuroinflammation associated with neurodegenerative disease., Objective: This study evaluated the safety, tolerability, pharmacokinetics, and pharmacodynamics of orally repeated administration of 5 μg, 10 μg, and 20 μg LSD in older healthy individuals. In the current paper, we present safety, tolerability, pharmacokinetics, and pharmacodynamic measures that relate to safety, tolerability, and dose response., Methods: This was a phase 1 double-blind, placebo-controlled, randomized study. Volunteers were randomly assigned to 1 of 4 dose groups (5 μg, 10 μg, 20 μg LSD, and placebo), and received their assigned dose on six occasions (i.e., every 4 days)., Results: Forty-eight older healthy volunteers (mean age = 62.9 years) received placebo (n = 12), 5 μg (n = 12), 10 μg (n = 12), or 20 μg (n = 12) LSD. LSD plasma levels were undetectable for the 5 μg group and peak blood plasma levels for the 10 μg and 20 μg groups occurred at 30 min. LSD was well tolerated, and the frequency of adverse events was no higher than for placebo. Assessments of cognition, balance, and proprioception revealed no impairment., Conclusions: Our results suggest safety and tolerability of orally administered 5 μg, 10 μg, and 20 μg LSD every fourth day over a 21-day period and support further clinical development of LSD for the treatment and prevention of Alzheimer's disease (AD).

Background: People with schizophrenia frequently have cognitive dysfunction, which does not respond to pharmacological interventions. Varenicline has been identified as a potential treatment option for nicotinic receptor dysfunction with a potential to treat cognitive impairment in schizophrenia., Methods: We conducted a systematic review of Pubmed, Embase, Psycinfo, CINAHL and the Cochrane Schizophrenia Trial Registry for randomised controlled trials of varenicline in people with schizophrenia for cognitive dysfunction. We excluded trials among people with dementia. We then undertook a meta-analysis with the primary outcome of difference in change of cognitive measures between varenicline and placebo as well as secondary outcomes of difference in rates of adverse events. We conducted a sensitivity analysis on smoking status and study duration., Results: We included four papers in the meta-analysis (n = 339). Varenicline was not superior to placebo for overall cognition (SMD = -0.022, 95% CI -0.154-0.110; Z = -0.333; p = 0.739), attention (SMD = -0.047, 95% CI -0.199-0.104; Z = -0.613; p = 0.540), executive function (SMD = -0.060, 95% CI -0.469-0.348; Z =- 0.290; p = 0.772) or processing speed (SMD = 0.038, 95% CI -0.232-0.308; Z = 0.279; p = 0.780). There was no difference in psychotic symptoms, but varenicline was associated with higher rates of nausea. Sensitivity analyses for smoking status and study duration did not alter the results., Conclusion: Within the present literature, varenicline does not appear to be a useful target compound for improving cognitive impairment in schizophrenia. Based on these results, a trial would need over 2500 participants to be powered to show statistically significant findings.