Emerging effects of temperature on human cognition, affect, and behaviour

Human body core temperature is tightly regulated within approximately 37 °C. Global near surface temperature has increased by over 1.2 °C between 1850 and 2020. In light of the challenge this poses to human thermoregulation, the present perspective article sought to provide an overview on the effects of varying ambient and body temperature on cognitive, affective, and behavioural domains of functioning. To this end, an overview of observational and experimental studies in healthy individuals and individuals with mental disorders was provided. Within body core temperature at approximately 37 °C, relatively lower ambient and skin temperatures appear to evoke a need for social connection, whereas comparably higher temperatures appear to facilitate notions of other as closer and more sociable. Above-average ambient temperatures are associated with increased conflicts as well as incident psychotic and depressive symptoms, mental disorders, and suicide. With mild hypo- and hyperthermia, paradoxical effects are observed: whereas the acute states are generally characterised by impairments in cognitive performance, anxiety, and irritability, individuals with depression experience longer-term symptom improvements with treatments deliberately inducing these states for brief amounts of time. When taken together, it has thus become clear that temperature is inexorably associated with human cognition, affect, and (potentially) behaviour. Given the projected increase in global warming, further research into the affective and behavioural sequelae of heat and the mechanisms translating it into mental health outcomes is urgently warranted.

Mindfulness-induced self-transcendence promotes universal love with consequent effects on opioid misuse

In addition to its health benefits, mindfulness has been theorized in classical contemplative frameworks to elicit self-transcendent experiences as a means of promoting universal love and compassion. Increasing feelings of love may be especially clinically relevant for the treatment of opioid misuse, in that addictive use of opioids dysregulates neurobiological processes implicated in the experience of love. Here we tested these hypotheses in a secondary analysis (n = 187) of data from a randomized clinical trial of Mindfulness-Oriented Recovery Enhancement (MORE) versus supportive psychotherapy for comorbid opioid misuse and chronic pain. At pre- and post-treatment, participants completed a measure of state self-transcendence immediately following a laboratory-based mindfulness task. Through 9-month follow-up, we assessed changes in universal love and opioid misuse. Participants also completed ecological momentary assessments of opioid craving during the 8-week study interventions and for the following month. Compared to supportive psychotherapy, participants in MORE reported significantly greater increases in mindfulness-induced self-transcendence, which mediated the effect of MORE on increased feelings of universal love. In turn, increases in universal love significantly predicted decreased opioid craving and lower odds opioid misuse through 1- and 9-month follow-ups, respectively. Findings suggest mindfulness-induced self-transcendence may promote feelings of universal love, with possible downstream benefits on reducing addictive behavior.

Divergent emotional and autonomic responses to Cyberball in patients with opioid use disorder on opioid agonist treatment

The perception of social exclusion among patients with opioid use disorder (OUD) could be affected by long-term opioid use. This study explores the emotional and cardiac autonomic responses to an experience of ostracism in a sample of participants with OUD on opioid agonist treatment (OAT). Twenty patients with OUD and twenty healthy controls (HC) performed a ball-tossing game (Cyberball) with two conditions: Inclusion and Ostracism. We measured self-reported ratings of perceived threat towards one's fundamental needs and respiratory sinus arrhythmia (RSA) immediately after the game and 10 min after Ostracism (Reflective stage). Following ostracism, participants with OUD self-reported blunted feelings of threat to the fundamental need to belong. RSA levels were significantly suppressed immediately after ostracism and during the Reflective stage in comparison with HC, indicating an autonomic alteration in response to threatening social situations. Finally, only among HC higher perceived threats towards fundamental needs predicted increases in RSA levels, suggesting an adaptive vagal regulation in response to a perceived threat. Conversely, among patients with OUD the subjective response to ostracism was not associated with the autonomic reaction. OAT may have a protective effect against negative feelings of ostracism. However patients with OUD on OAT present poor autonomic regulation in response to social threats, which could reflect their trait hypersensitivity to social rejection.

Male-selective effects of oxytocin agonism on alcohol intake: behavioral assessment in socially housed prairie voles and involvement of RAGE

Targeting the oxytocin (OXT) peptide system has emerged as a promising new approach for the treatment of alcohol use disorder (AUD). However, further advancements in this development depend on properly modeling various complex social aspects of AUD and its treatment. Here we examined behavioral and molecular underpinnings of OXT receptor (OXTR) agonism in prairie voles, a rodent species with demonstrated translational validity for neurobiological mechanisms regulating social affiliations. To further improve translational validity of these studies, we examined effects of intranasal (IN) OXT administration in male and female prairie voles socially housed in the presence of untreated cagemates. IN OXT selectively inhibited alcohol drinking in male, but not female, animals. Further, we confirmed that exogenously administered OXT penetrates the prairie vole brain and showed that Receptor for Advanced Glycation End-products assists this penetration after IN, but not intraperitoneal (IP), OXT administration. Finally, we demonstrated that IP administration of LIT-001, a small-molecule OXTR agonist, inhibits alcohol intake in male, but not female, prairie voles socially housed in the presence of untreated cagemates. Taken together, results of this study support the promise of selectively targeting OXTR for individualized treatment of AUD.

"There's No Sewing Classes, There's No Bedazzling Seminars": The Impact of Masculinity on Social Connectedness and Mental Health for Men Living in Inner-Regional Australia

Regional Australian masculinities are typified by 'traditional' values (e.g., stoicism, self-reliance) known to restrict social connectedness. Thus, these masculinities have been implicated in worsening men's mental health. What remains unclear, however, is how men living in inner-regional communities (i.e., townships on the fringes of major cities) might uniquely experience masculinity, social connectedness, and mental health. We interviewed 29 boys/men and one non-binary participant (M _age = 43.77 years) living in the Macedon Ranges (an inner-regional Australian community). Using reflexive thematic analysis, we generated three themes. Participants described inner-regional masculinities as traditional and rigid, and attributed the Macedon Ranges' comparatively high suicide rate to these masculinities. Conversely, migration from the neighbouring city of Melbourne was implicated in introducing more inclusive masculinities to the area that conflicted with existing masculine norms. Thus, Macedon Ranges men were framed as ultimately lacking a cohesive community identity. Proximity to Melbourne was described as encouraging local men to commute daily for work instead of working locally, thereby further weakening community identity. Overall, these phenomena were implicated in damaging the psychosocial wellbeing of local men via reducing social connectedness. Because men's mental illness is so pervasive within regional Australian communities, these findings have direct implications for policymakers. Namely, policies need to acknowledge that masculinities directly influence mental health and that inner-regional masculinities are impacted by unique place-based considerations distinct from men living in other regional communities.

Effects of the mu-opioid receptor agonist morphine on facial mimicry and emotion recognition

Facial mimicry and emotion recognition are two socio-cognitive abilities involved in adaptive socio-emotional behavior, promoting affiliation and the establishment of social bonds. The mu-opioid receptor (MOR) system plays a key role in affiliation and social bonding. However, it remains unclear whether MORs are involved in the categorization and spontaneous mimicry of emotional facial expressions. Using a randomized, placebo-controlled, double-blind, between-subjects design, we investigated in 82 healthy female volunteers the effects of the specific MOR agonist morphine on the recognition accuracy of emotional faces (happiness, anger, fear), and on their facial mimicry (measured with electromyography). Frequentist statistics did not reveal any significant effects of drug administration on facial mimicry or emotion recognition abilities. However, post hoc Bayesian analyses provided support for an effect of morphine on facial mimicry of fearful facial expressions. Specifically, compared to placebo, morphine reduced mimicry of fear, as shown by lower activity of the frontalis muscle. Bayesian analyses also provided support for the absence of a drug effect on mimicry of happy and angry facial expressions, which were assessed with the zygomaticus major and corrugator supercilii muscles, as well as on emotion recognition accuracy. These findings suggest that MOR activity is involved in automatic facial responses to fearful stimuli, but not in their identification. Overall, the current results, together with the previously reported small effects of opioid compounds, suggest a relatively marginal role of the MOR system in emotion simulation and perception.

Resting (Tonic) Blood Pressure Is Associated With Sensitivity to Imagined and Acute Experiences of Social Pain: Evidence From Three Studies

Social pain is a common experience that has potent implications for health. However, individuals differ in their sensitivity to social pain. Recent evidence suggests that sensitivity to social pain varies according to a biological factor that modulates sensitivity to physical pain: resting (tonic) blood pressure. The current studies extended this evidence by testing whether blood pressure relates to sensitivity to imagined (Study 1: N = 762, 51% female adults) and acute (Study 2, preregistered: N = 204, 57% female adults) experiences of social pain and whether associations extend to general emotional responding (Studies 1-3; Study 3: N = 162, 59% female adults). In line with prior evidence, results showed that higher resting blood pressure was associated with lower sensitivity to social pain. Moreover, associations regarding blood pressure and sensitivity to social pain did not appear to be explained by individual differences in general emotional responding. Findings appear to be compatible with the interpretation that social and physical pain share similar cardiovascular correlates and may be modulated by convergent interoceptive pathways.

Toward a New Science of Psychedelic Social Psychology: The Effects of MDMA (Ecstasy) on Social Connection

Psychedelic science has generated hundreds of compelling published studies yet with relatively little impact on mainstream psychology. I propose that social psychologists have much to gain by incorporating psychoactive substances into their research programs. Here I use (±)-3,4-methylenedioxymethamphetamine (MDMA) as an example because of its documented ability in experiments and clinical trials to promote bonding, love, and warmth. Social connection is a fundamental human need, yet researchers still possess few tools to effectively and durably boost it. MDMA allows investigators to isolate the psychological mechanisms-as well as brain pathways-underlying felt social connection and thus reveal what should be targeted in future (nondrug) studies. Accordingly, I introduce a conceptual model that presents the proximal psychological mechanisms stimulated by MDMA (lowered fear, increased sociability, more chemistry), as well as its potential long-term impacts (improved relationships, reduced loneliness, stronger therapeutic alliances). Finally, I discuss further questions (e.g., whether using MDMA for enhancing connection can backfire) and promising research areas for building a new science of psychedelic social psychology. In sum, psychopharmacological methods can be a useful approach to illuminate commonly studied social-psychological processes, such as connectedness, prejudice, or self, as well as inform interventions to directly improve people's lives.

We're Not That Choosy: Emerging Evidence of a Progression Bias in Romantic Relationships

Dating is widely thought of as a test phase for romantic relationships, during which new romantic partners carefully evaluate each other for long-term fit. However, this cultural narrative assumes that people are well equipped to reject poorly suited partners. In this article, we argue that humans are biased toward pro-relationship decisions-decisions that favor the initiation, advancement, and maintenance of romantic relationships. We first review evidence for a progression bias in the context of relationship initiation, investment, and breakup decisions. We next consider possible theoretical underpinnings-both evolutionary and cultural-that may explain why getting into a relationship is often easier than getting out of one, and why being in a less desirable relationship is often preferred over being in no relationship at all. We discuss potential boundary conditions that the phenomenon may have, as well as its implications for existing theoretical models of mate selection and relationship development.

Associations between parenting representations and behavior among young mothers and mothers with opioid use disorder

Mothers' representations reflect how they experience their child and their relationship, and can guide parenting behavior. While studies of representations typically focus on infancy, this study examines associations between mothers' representations and behavior with their preschoolers using two samples: young mothers (n = 201; 42% African American, 42% Latina, 8% European-American, 8% multi-ethnic; M_age  = 32 months) and mothers in treatment for opioid use disorder (OUD; n = 150; 100% African American; M_age  = 49 months). This study aims to identify the distribution of representations within these populations, differences in parenting between mothers classified with balanced and non-balanced representations, and distinct parenting behaviors associated with distorted and disengaged representations. The Working Model of the Child Interview was conducted to assess representations, and mother-child interactions were video-recorded. The distribution of balanced, distorted, and disengaged representations was 59%, 25%, and 15% among young mothers, and 21%, 39%, and 40% among mothers with OUD. Balanced representations (coherent, rich, engaged, respectful) were associated with positive parenting, including sensitivity, autonomy support, cognitive support and less negative regard among young mothers, and sensitivity and encouragement in the OUD sample. Mothers with disengaged representations (emotionally distant, lacking detail, indifferent) demonstrated less support for learning compared to mothers with distorted representations (involved but inconsistent, negative, or bizarre descriptions of child).

Blocking mu-opioid receptors inhibits social bonding in rituals

Religious rituals are universal human practices that play a seminal role in community bonding. In two experiments, we tested the role of mu-opioids as the active factor fostering social bonding. We used a mu-opioid blocker (naltrexone) in two double-blind studies of rituals from different religious traditions. We found the same effect across both studies, with naltrexone leading to significantly lower social bonding compared with placebo. These studies suggest that mu-opioids play a significant role in experiences of social bonding within ritual contexts.

The neurobiological reward system in Prolonged Grief Disorder (PGD): A systematic review

Prolonged Grief Disorder (PGD) is a debilitating condition affecting between 7% and 10% of bereaved individuals. Past imaging and psychological studies have proposed links between PGD's characteristic symptoms - in particular, profound yearning - and the neural reward system. We conducted a systematic review to investigate this connection. On December 19, 2019, we searched six bibliographic databases for data on the neurobiology of grief and disordered grief. We excluded studies of the hypothalamic-pituitary-adrenal (HPA) axis, animal studies, and reviews. After abstract and full-text screening, twenty-four studies were included in the final review. We found diverse evidence for the activation of several reward-related regions of the brain in PGD. The data reviewed suggest that compared to normative grief, PGD involves a differential pattern of activity in the amygdala and orbitofrontal cortex (OFC); likely differential activity in the posterior cingulate cortex (PCC), rostral or subgenual anterior cingulate cortex (ACC), and basal ganglia overall, including the nucleus accumbens (NAc); and possible differential activity in the insula. It also appears that oxytocin signaling is altered in PGD, though the exact mechanism is unclear. Our findings appear to be consistent with, though not confirmative of, conceptualizing PGD as a disorder of reward, and identify directions for future research.

Music as a coevolved system for social bonding

Why do humans make music? Theories of the evolution of musicality have focused mainly on the value of music for specific adaptive contexts such as mate selection, parental care, coalition signaling, and group cohesion. Synthesizing and extending previous proposals, we argue that social bonding is an overarching function that unifies all of these theories, and that musicality enabled social bonding at larger scales than grooming and other bonding mechanisms available in ancestral primate societies. We combine cross-disciplinary evidence from archaeology, anthropology, biology, musicology, psychology, and neuroscience into a unified framework that accounts for the biological and cultural evolution of music. We argue that the evolution of musicality involves gene-culture coevolution, through which proto-musical behaviors that initially arose and spread as cultural inventions had feedback effects on biological evolution due to their impact on social bonding. We emphasize the deep links between production, perception, prediction, and social reward arising from repetition, synchronization, and harmonization of rhythms and pitches, and summarize empirical evidence for these links at the levels of brain networks, physiological mechanisms, and behaviors across cultures and across species. Finally, we address potential criticisms and make testable predictions for future research, including neurobiological bases of musicality and relationships between human music, language, animal song, and other domains. The music and social bonding (MSB) hypothesis provides the most comprehensive theory to date of the biological and cultural evolution of music.

Endogenous Opioids at the Intersection of Opioid Addiction, Pain, and Depression: The Search for a Precision Medicine Approach

Opioid addiction and overdose are at record levels in the United States. This is driven, in part, by their widespread prescription for the treatment of pain, which also increased opportunity for diversion by sensation-seeking users. Despite considerable research on the neurobiology of addiction, treatment options for opioid abuse remain limited. Mood disorders, particularly depression, are often comorbid with both pain disorders and opioid abuse. The endogenous opioid system, a complex neuromodulatory system, sits at the neurobiological convergence point of these three comorbid disease states. We review evidence for dysregulation of the endogenous opioid system as a mechanism for the development of opioid addiction and/or mood disorder. Specifically, individual differences in opioid system function may underlie differences in vulnerability to opioid addiction and mood disorders. We also review novel research, which promises to provide more detailed understanding of individual differences in endogenous opioid neurobiology and its contribution to opioid addiction susceptibility.

Opioid receptor blockade inhibits self-disclosure during a closeness-building social interaction

Social ties are critical to human health and well-being; thus, it is important to gain a better understanding of the neurobiological mechanisms involved in the development of interpersonal closeness. Prior research indicates that endogenous opioids may play a role in social affiliation by elaborating feelings of social connection and warmth; however, it is not currently known whether opioids mediate affiliative behavior and emerging feelings of closeness in humans at the relationship initiation stage. This randomized, double-blind study examined opioidergic processes in the context of a naturalistic, face-to-face social interaction. Eighty pairs of unacquainted participants (final N = 159 due to removal of one dyad member from analysis) received either 50 mg of the opioid receptor antagonist naltrexone or placebo prior to completing a closeness-building exercise centered on escalating self-disclosure (sharing of personal information about the self). Compared to the placebo group, naltrexone participants held lower social reward expectations prior to the interaction, engaged in less intimacy-fostering behavior (self-disclosure) during the interaction, and reported wanting less closeness with their partner. Feelings of social connection were not significantly lower in the naltrexone group. However, placebo participants experienced improvements in mood after the closeness-building task whereas naltrexone participants did not. These findings suggest that endogenous opioids may contribute to behavioral, affective, and motivational processes related to the development of initial closeness.

A novel theory on the predictive value of variation in the β-endorphin system on the risk and severity of PTSD

Despite growing interest in genetic and psychosocial indicators of heightened susceptibility to posttraumatic stress disorder (PTSD), a predictive model, which explains why some individuals develop PTSD in response to life-threatening traumatic events, while others, when faced with the same or similar experiences, do not, has thus far remained out of reach. In this paper, we review the literature on gene-environment interactions in β-endorphin system functioning with regard to PTSD and suggest that variation, both genetic and with regard to environmental stimuli, in systems which, like the β-endorphin system, distort human perception of life-threatening traumatic experiences may account for some of the variance in resilience to the disorder. Given the role of β-endorphin in both social connections and physical exercise, this becomes especially relevant with regard to military selection, training, and leadership processes.

The Endogenous Opioid System: Role and Dysfunction Caused by Opioid Therapy

The endogenous opioid system is comprised of a wide array of receptors and ligands that are present throughout the central and peripheral nervous system, the gastrointestinal tract, and the immune system. This explains the multitude of physiological functions it is responsible for including analgesia, mood regulation, and modulation of the stress response. It also plays a pivotal role in modulating the brain's reward center with behavioral and social implications on mood disorders and addiction. Exogenous opioid therapy hijacks the endogenous system and alters its functions contributing to an imbalance that is responsible for the pathogenesis of several disease states.

Early Secure Attachment as a Protective Factor Against Later Cognitive Decline and Dementia

The etiology of neurodegenerative disorders such as dementia is complex and incompletely understood. Interest in a developmental perspective to these pathologies is gaining momentum. An early supportive social environment seems to have important implications for social, affective and cognitive abilities across the lifespan. Attachment theory may help to explain the link between these early experiences and later outcomes. This theory considers early interactions between an infant and its caregiver to be crucial to shaping social behavior and emotion regulation strategies throughout adult life. Furthermore, research has demonstrated that such early attachment experiences can, potentially through epigenetic mechanisms, have profound neurobiological and cognitive consequences. Here we discuss how early attachment might influence the development of affective, cognitive, and neurobiological resources that could protect against cognitive decline and dementia. We argue that social relations, both early and late in life, are vital to ensuring cognitive and neurobiological health. The concepts of brain and cognitive reserve are crucial to understanding how environmental factors may impact cognitive decline. We examine the role that attachment might play in fostering brain and cognitive reserve in old age. Finally, we put forward the concept of affective reserve, to more directly frame the socio-affective consequences of early attachment as protectors against cognitive decline. We thereby aim to highlight that, in the study of aging, cognitive decline and dementia, it is crucial to consider the role of affective and social factors such as attachment.

Implications for Reward Processing in Differential Responses to Loss: Impacts on Attachment Hierarchy Reorganization

When an attachment relationship is severed, so is homeostatic maintenance, leading to dysregulation of multiple physiological systems. Expanding upon Sbarra and Hazan's original model, we suggest that the degree to which an individual's physiological systems remain dysregulated depends on the state of one's attachment hierarchy-namely, whether an individual continues to seek a lost partner for support as their primary attachment figure. To recover from the loss of a romantic partner, an individual's attachment hierarchy must be reorganized. Our model proposes that an individual will go through a series of physiological changes before their attachment hierarchy is reorganized, which can either help or hinder their recovery. We consider the role of reward processing, including endogenous opioids, in this recovery process. Along the way, we identify mechanisms for continued dysregulation of biological systems among those who take longer to recover from a loss.

Naltrexone alters responses to social and physical warmth: implications for social bonding

Socially warm experiences, when one feels connected to others, have been linked with physical warmth. Opioids, hypothesized to support social bonding with close others and, separately, physical warmth, may underlie both experiences. In order to test this hypothesis, 80 participants were randomly assigned to the opioid antagonist, naltrexone or placebo before neural and emotional responses to social and physical warmth were collected. Social and physical warmth led to similar increases in ventral striatum (VS) and middle-insula (MI) activity. Further, feelings of social connection were positively related to neural activity to social warmth. However, naltrexone (vs placebo) disrupted these effects by (i) reducing VS and MI activity to social and physical warmth, (ii) erasing the subjective experience-brain association to social warmth and (iii) disrupting the neural overlap between social and physical warmth. Results provide additional support for the theory that social and physical warmth share neurobiological, opioid receptor-dependent mechanisms and suggest multiple routes by which social connections may be maintained.