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RationaleAnimal studies and anecdotal human reports suggest that cannabinoids have antinociceptive effects. Controlled human studies have produced mixed results.ObjectivesWe sought to reduce existing variability by investigating the effects of intravenous delta-9-tetrahydrocannabinol (THC) in several pain paradigms within the same human subjects, addressing some of the limitations to the published literature.MethodsIn this exploratory randomized, double-blind, placebo-controlled, cross-over study, healthy human subjects received 0.01 mg/kg or 0.03 mg/kg intravenous THC or placebo (ethanol vehicle) infused over 10 min on three test days, each separated by at least 72 h. Capsaicin (250 μg) was injected intradermally to induce chemical pain and hyperalgesia. Four other forms of acute pain were induced: mechanical (von Frey filament), hot and cold (thermode), and electrical (pulse generator). Pain ratings were obtained before drug administration, at peak drug effects, and 2 h after drug administration and included both objective and subjective measures. THC drug effects and vital signs were also collected during experimental sessions. Nonparametric analysis with repeated measures was performed.ResultsTHC induced euphoria, perceptual and cognitive alterations, and tachycardia in a dose-related manner, but failed to have significant effects in experimentally induced acute chemical, mechanical, thermal, or electrical pain and capsaicin-induced hyperalgesia.ConclusionsIn this exploratory controlled study, intravenous THC lacked significant antinociceptive properties in experimental models of acute pain and capsaicin-induced hyperalgesia in healthy human subjects. Continued study of THC and other cannabinoids through high-quality, controlled studies in both healthy volunteers and patients with pain conditions is warranted to inform the growing demand for the clinical application of cannabinoids in pain management.

RationaleOne risk factor for alcohol and substance misuse is hypomanic experiences, or periods of mood elevation. Young people who report hypomanic states are more likely to develop bipolar disorder (BP), and BP and other mood disorders increase the risk of addiction. We recently reported that young adults with a history of mood elevation experience less subjective effects from a low dose of alcohol, which may be predictive of future alcohol use. The finding with alcohol raised the question of whether this dampened response to a drug also applies to other drugs, such as amphetamine.ObjectiveThis study assessed responses of d-amphetamine in healthy young adults with varying experiences of mood elevation, as measured by the Mood Disorders Questionnaire (MDQ).MethodsHealthy 18–19-year-olds (N = 30) with a range of MDQ scores participated in three 4-h laboratory sessions in which they received placebo, 10 mg, or 20 mg d-amphetamine. They completed mood questionnaires and cardiovascular measures.ResultsIndividuals with higher MDQ scores reported less stimulation and euphoria after 10 mg, but not 20 mg, d-amphetamine, than individuals with lower scores. MDQ scores were not related to cardiovascular responses to the drug.ConclusionsA history of mood elevation experiences or hypomania states is related to dampened response to a low dose of a psychostimulant drug, extending previous findings with dampened response to alcohol. This phenotype for mood disorders of dampened responses to drugs may contribute to risk for subsequent drug use or misuse.

Poor inhibitory control and sensitivity to drug reward are two significant risk factors for drug abuse. Although the two have been largely viewed as separate and independent risk factors, there is new evidence to suggest that they may be related at both the behavioral and neural level. This study examined associations between behavioral and neural correlates of inhibitory control and sensitivity to the subjective rewarding effects of amphetamine in humans. Healthy volunteers (n=63) first completed the stop signal task, a behavioral measure of inhibitory control. Then they participated in four sessions in which they received amphetamine (20 mg) and placebo in alternating order, providing self-report measures of euphoria and arousal at regular intervals. Finally, a subset of participants (n=38) underwent an fMRI scan to assess neural correlates of inhibitory control. In the first phase of the study, participants with longer stop signal reaction time (SSRT) reported greater amphetamine-induced euphoria and stimulation than those with shorter SSRT. In the second phase, fMRI of response inhibition showed the expected activation in right prefrontal regions. Further, individuals who exhibited less activation in the right middle frontal gyrus during the inhibition task reported more euphoria during the amphetamine sessions. This study is the first to show associations between poor inhibitory control and amphetamine reward sensitivity at both behavioral and neural levels in humans. These findings extend our understanding of risk for drug abuse in individuals with poor inhibitory control and suggest novel targets for prevention efforts.

Rationale and objective Preference for sweet taste rewards has been linked to the propensity for drug use in both animals and humans. Here, we tested the association between sweet taste liking and sensitivity to amphetamine reward in healthy adults. We hypothesized that sweet likers would report greater euphoria and stimulation following d -amphetamine (20 mg) compared to sweet dislikers. Methods Men ( n  = 36) and women ( n  = 34) completed a sweet taste test in which they rated their liking of various concentrations of sucrose and filtered water (0.05, 0.10, 0.21, 0.42, and 0.83 M). Participants who preferred the highest concentration were classified as “sweet likers.” All others were classified as “sweet dislikers.” They then completed four sessions in which they received d -amphetamine (20 mg) and placebo in alternating order, providing self-report measures of euphoria and stimulation on the Addiction Research Center Inventory (ARCI) at regular intervals. We conducted linear mixed effects models to examine relationships between sweet liking and drug-induced euphoria and stimulation. Results Sweet likers reported significantly greater amphetamine-induced euphoria than did sweet dislikers among women. By contrast, sweet liking was not associated with amphetamine response in men. No associations with stimulation were observed. Conclusion The association between sweet preference and amphetamine response in women is consistent with animal studies linking sweet taste preference and drug reward and also fits with observations that individuals who use drugs show a preference for sweet tastes. Whether the sex difference is related to circulating hormones, or other variables, remains to be determined.

Ayahuasca is a South American psychoactive plant tea which contains the serotonergic psychedelic N,N-dimethyltryptamine (DMT) and monoamine-oxidase inhibitors that render DMT orally active. Previous investigations with ayahuasca have highlighted a psychotropic effect profile characterized by enhanced introspective attention, with individuals reporting altered somatic perceptions and intense emotional modifications, frequently accompanied by visual imagery. Despite recent advances in the study of ayahuasca pharmacology, the neural correlates of acute ayahuasca intoxication remain largely unknown. To investigate the effects of ayahuasca administration on regional cerebral blood flow. Fifteen male volunteers with prior experience in the use of psychedelics received a single oral dose of encapsulated freeze-dried ayahuasca equivalent to 1.0 mg DMT/kg body weight and a placebo in a randomized double-blind clinical trial. Regional cerebral blood flow was measured 100-110 min after drug administration by means of single photon emission tomography (SPECT). Ayahuasca administration led to significant activation of frontal and paralimbic brain regions. Increased blood perfusion was observed bilaterally in the anterior insula, with greater intensity in the right hemisphere, and in the anterior cingulate/frontomedial cortex of the right hemisphere, areas previously implicated in somatic awareness, subjective feeling states, and emotional arousal. Additional increases were observed in the left amygdala/parahippocampal gyrus, a structure also involved in emotional arousal. The present results suggest that ayahuasca interacts with neural systems that are central to interoception and emotional processing and point to a modulatory role of serotonergic neurotransmission in these processes.

Racialized migrant transgender women engaged in sex work represent an understudied population. They face unique challenges resulting from their multiple marginalized identities, such as racialized transmisogyny. Since marginalized communities play a vital role in mitigating systemic stigma, it is essential to expand the literature on the community of this population. The present study used the frameworks of gender minority stress and intersectionality, along with a decolonial and transfeminist approach. Twenty participants aged between 28 and 66 years old ( M  = 43.15; SD  = 10.49) took part in a semi-structured interview. Thematic analysis identified two main areas with ten corresponding themes. “The double bind of community” described the complex dynamics experienced by transgender refugees within their community, including (1) sex work between emancipation and exploitation, (2) non-prescribed treatments for gender affirmation, (3) negative experiences with the community, (4) positive impact of trans organizations, and (5) practical and economic support and exploitation. “The identification with the community” highlighted how participants positively or negatively identified with the community, containing: (6) awareness of one’s privileges and oppressions, (7) internalized cisgenderism and assimilation, (8) gender euphoria; (9) sexual objectification, and (10) trans-generativity. The study evidenced the complex dynamics within marginalized communities. Trauma, stigma, and survival struggles can lead to violence and exploitation within the community. However, the community also has the potential to promote positive feelings and generativity. These findings have practical implications for social workers, healthcare practitioners, and researchers, emphasizing the need for appropriate and culturally competent care, including resources for coping with stress, fostering resilience, and facilitating post-traumatic growth.

Introduction Internationally, research has shown Lesbian, Gay, Bisexual, Transgender/gender diverse, and Queer (LGBTQ+) people experience multifaceted challenges within school contexts. However, there is only a small emergent body of research on how LGBTQ+ community members might also experience positive, joyful, or euphoric experiences in these same spaces. Using euphoria and minority stress models, this article aims to consider whether schools themselves can be supportive and protective environments for LGBTQ+ people, how features of the school environment and school community might enable experiences of LGBTQ+ -related euphoria, and how euphoric experiences may be similar for students, staff and parents, and cisgender and gender diverse (GD) members of the LGBTQ+ community.MethodsThe study employed elements of grounded theory to analyse survey responses of LGBTQ+ students (n = 706), school staff (n = 107), and parents (n = 57). The survey data was collected online from 2021 to 2022 and explored LGBTQ+ community members’ experiences in, and perceptions of, Australian schools.ResultsEuphoria was predominantly related to school social contexts (such as supportive social climates), followed by school practices (such as LGBTQ+ representation), and internal experiences (such as pride). These events were shared by students, staff, and parents similarly. Euphoric events were shared by cisgender and GD participants, although gender-affirming social contexts and school practices were valued particularly by GD students, parents, and staff.ConclusionsSchools can act as supportive contexts for LGBTQ+ students, staff, and parents in terms of social characteristics and school practices using mostly similar methods. Implications for policy development include school-wide interventions that include and reflect all LGBTQ+ people in all education-based roles, via school curricula and activities, public education, and awareness-raising endeavours.Policy ImplicationsImplications for policy development include school-wide interventions that include and reflect all LGBTQ+ people in all education-based roles, via school curricula and activities, public education and awareness-raising endeavours.

Willingness to lay down one’s life for a group of non-kin, well documented historically and ethnographically, represents an evolutionary puzzle. Building on research in social psychology, we develop a mathematical model showing how conditioning cooperation on previous shared experience can allow individually costly pro-group behavior to evolve. The model generates a series of predictions that we then test empirically in a range of special sample populations (including military veterans, college fraternity/sorority members, football fans, martial arts practitioners, and twins). Our empirical results show that sharing painful experiences produces “identity fusion” – a visceral sense of oneness – which in turn can motivate self-sacrifice, including willingness to fight and die for the group. Practically, our account of how shared dysphoric experiences produce identity fusion helps us better understand such pressing social issues as suicide terrorism, holy wars, sectarian violence, gang-related violence, and other forms of intergroup conflict.

Litchi (lychee) and the related fruit longan are grown extensively in China and South-East Asia, as well as in Australia, Florida (USA), Southern Europe and Southern Africa. This book represents the only comprehensive, balanced and internationally focused publication on these fruit. It covers all aspects of production, from taxonomy and breeding, to propagation, flowering and fruit set, to diseases, pests and postharvest storage and processing. It also contains information on photosynthesis, productivity, plant-water relations and nutrition.

Combining positron emission tomography and functional magnetic resonance imaging, the authors investigate the effects of emotionally arousing music on the dopamine system. They find that the anticipation of this abstract reward can result in dopamine release in an anatomical pathway that is distinct from that associated with the peak pleasure itself. Music, an abstract stimulus, can arouse feelings of euphoria and craving, similar to tangible rewards that involve the striatal dopaminergic system. Using the neurochemical specificity of [ 11 C]raclopride positron emission tomography scanning, combined with psychophysiological measures of autonomic nervous system activity, we found endogenous dopamine release in the striatum at peak emotional arousal during music listening. To examine the time course of dopamine release, we used functional magnetic resonance imaging with the same stimuli and listeners, and found a functional dissociation: the caudate was more involved during the anticipation and the nucleus accumbens was more involved during the experience of peak emotional responses to music. These results indicate that intense pleasure in response to music can lead to dopamine release in the striatal system. Notably, the anticipation of an abstract reward can result in dopamine release in an anatomical pathway distinct from that associated with the peak pleasure itself. Our results help to explain why music is of such high value across all human societies.