Oxytocin and the social brain: beware the complexity

Design of a randomized controlled trial examining the efficacy of oxytocin to enhance alcohol behavioral couple therapy

Combining pharmacological interventions with evidence-based behavioral interventions may help optimize treatment outcomes for alcohol use disorder (AUD). While several effective behavioral interventions for AUD have been developed, the vast majority target individual patients, despite evidence that behavioral interventions for couples have the ability to outperform individual treatments for AUD. Alcohol Behavioral Couples Therapy (ABCT) is an evidence-based behavioral intervention for couples that has been shown to significantly reduce AUD severity as well as improve relationship functioning. Accumulating evidence suggests that the neuropeptide oxytocin has the ability to reduce alcohol craving and consumption, symptoms of tolerance and withdrawal, and ameliorate neurobiological deficits associated with AUD. Furthermore, oxytocin has demonstrated the ability to increase prosocial behavior and cognition, and restore sensitivity to natural rewards such as interpersonal relationships. No study to date has examined the ability of oxytocin to enhance ABCT. Thus, the primary objective of this Phase II study is to examine the effects of oxytocin versus placebo in combination with ABCT in reducing AUD severity and improving relationship functioning. We also will utilize neuroimaging techniques before and after treatment to investigate the underlying pathophysiology of AUD among couples and identify prognostic indicators of treatment outcome. The findings from this study might provide critical new information to help inform clinical practice and accelerate research on the pharmacological treatment of AUD.

Effects of Oxytocin on Emotional and Physiological Responses to Conflict in Couples with Substance Misuse

Social stress, especially dyadic conflict among couples, is an important correlate of addiction. Several authors have suggested that the neuropeptide oxytocin (OT) may be useful in the treatment of couples with substance misuse. However, the literature examining OT among couples is scant and has yielded mixed findings. The current study examined the effects of OT versus placebo on emotional (e.g., warmth and anger) and physiological (e.g., skin conductance and heart rate) reactivity to a conflict resolution task in 30 heterosexual couples (N=60) in which one or both members misused substances. Using a randomized, double-blind, placebo-controlled design, both partners within each dyad were randomized to the same treatment condition. Participants completed a standardized conflict resolution task at baseline and 45 minutes following drug self-administration. Physiological measures were examined continuously during the laboratory tasks and emotional reactivity was self-reported at baseline and at 5 time points over the course of 1 hour following the second conflict resolution task. Results of a multi-level growth curve model accounting for baseline scores, gender and drug condition indicate that positive emotional experiences and skin conductance measures increased over the 5 time points. Neither drug condition nor gender was significantly related to outcomes, and no interaction effects were observed. These findings highlight the complexities involved in translational OT research and suggest that the impact of OT on key outcomes requires further exploration in regards to OT's potential therapeutic benefit.

Intimate partner violence moderates the association between oxytocin and reactivity to dyadic conflict among couples

Emerging literature indicates individual and contextual differences impact response to oxytocin (OT). Intimate partner violence (IPV) is one chronic stressor that may moderate OT response. To test the hypothesis that IPV moderates the association between OT and reactivity to a dyadic conflict task, data from a larger randomized controlled study was collected from heterosexual couples (N = 60 individuals; 30 couples) at high risk for IPV due to substance misuse. Partners within each dyad completed a 10-minute dyadic conflict task in the laboratory, and then self-administered a single dose of OT (40 IU) or placebo. Forty-five minutes later, participants completed another 10-minute dyadic conflict task. Stress reactivity was measured before and after the second conflict task using neuroendocrine (i.e., salivary cortisol), physiological (i.e., skin conductance), and subjective responses. Couple conflict behaviors were observed during the conflict tasks and assessed using a validated coding system. Among women, physical IPV modulated skin conductance in those administered OT, and OT interacted with physical and psychological IPV to yield less positive subjective and behavioral responses. No main or moderating effects were found for men. Findings support emerging literature on sex differences in response to OT. Future research is needed to effectively translate OT into therapeutic intervention.

Moral Enhancement as a Collective Action Problem

In light of the magnitude of interpersonal harm and the risk of greater harm in the future, Ingmar Persson and Julian Savulescu have argued for pharmacological enhancement of moral behaviour. I discuss moral bioenhancement as a set of collective action problems. Psychotropic drugs or other forms of neuromodulation designed to enhance moral sensitivity would have to produce the same or similar effects in the brains of a majority of people. Also, a significant number of healthy subjects would have to participate in clinical trials testing the safety and efficacy of these drugs, which may expose them to unreasonable risk. Even if the drugs were safe and effective, a majority of people would have to co-operate in a moral enhancement programme for such a project to succeed. This goal would be thwarted if enough people opted out and decided not to enhance. To avoid this scenario, Persson and Savulescu argue that moral enhancement should be compulsory rather than voluntary. But the collective interest in harm reduction through compulsory enhancement would come at the cost of a loss of individual freedom. In general, there are many theoretical and practical reasons for scepticism about the concept and goal of moral enhancement.

Effects of oxytocin on working memory and executive control system connectivity in posttraumatic stress disorder

Posttraumatic stress disorder (PTSD) is a chronic, debilitating condition for which effective medications are scant and little is known about neural correlates of risk versus resilience. Oxytocin is a hypothalamic neuropeptide that has demonstrated promise in modulating neurobiological and behavioral correlates of PTSD. Cognitive deficits in areas such as working memory and executive control are highly prevalent among individuals with PTSD and oxytocin might modulate these impairments in individuals with PTSD. Using a double-blind, placebo-controlled design, this study employed functional MRI (fMRI) and the n-back working memory task to examine the effects of oxytocin (24 IU) versus placebo on working memory and dorsolateral prefrontal cortex (DLPFC) connectivity among individuals with PTSD (n = 16) as compared with a trauma-exposed control group (n = 18). Results indicate that individuals with PTSD on oxytocin performed better in the 2-back condition of the n-back task compared with individuals with PTSD on placebo. Results also indicate that connectivity between DLPFC and anterior cingulate increased in the 2-back condition among individuals with PTSD on oxytocin as compared with placebo. These findings provide preliminary evidence of an effect of oxytocin on working memory among individuals with PTSD and insights into the neurobiological mechanisms underlying this association. Future studies are necessary to understand the mechanisms responsible for working memory deficits in PTSD and to examine the potential of oxytocin for use as a treatment for PTSD. (PsycINFO Database Record

Oxytocin facilitates adaptive fear and attenuates anxiety responses in animal models and human studies-potential interaction with the corticotropin-releasing factor (CRF) system in the bed nucleus of the stria terminalis (BNST)

Despite its relatively well-understood role as a reproductive and pro-social peptide, oxytocin (OT) tells a more convoluted story in terms of its modulation of fear and anxiety. This nuanced story has been obscured by a great deal of research into the therapeutic applications of exogenous OT, driving more than 400 ongoing clinical trials. Drawing from animal models and human studies, we review the complex evidence concerning OT's role in fear learning and anxiety, clarifying the existing confusion about modulation of fear versus anxiety. We discuss animal models and human studies demonstrating the prevailing role of OT in strengthening fear memory to a discrete signal or cue, which allows accurate and rapid threat detection that facilitates survival. We also review ostensibly contrasting behavioral studies that nonetheless provide compelling evidence of OT attenuating sustained contextual fear and anxiety-like behavior, arguing that these OT effects on the modulation of fear vs. anxiety are not mutually exclusive. To disambiguate how endogenous OT modulates fear and anxiety, an understudied area compared to exogenous OT, we survey behavioral studies utilizing OT receptor (OTR) antagonists. Based on emerging evidence about the role of OTR in rat dorsolateral bed nucleus of stria terminalis (BNST) and elsewhere, we postulate that OT plays a critical role in facilitating accurate discrimination between stimuli representing threat and safety. Supported by human studies, we demonstrate that OT uniquely facilitates adaptive fear but reduces maladaptive anxiety. Last, we explore the limited literature on endogenous OT and its interaction with corticotropin-releasing factor (CRF) with a special emphasis on the dorsolateral BNST, which may hold the key to the neurobiology of phasic fear and sustained anxiety.

Effects of oxytocin on cortisol reactivity and conflict resolution behaviors among couples with substance misuse

Social stress, particularly in the form of dyadic conflict, is a well-established correlate of substance use disorders (SUD). The neuropeptide oxytocin can enhance prosocial behavior and mitigate addictive behaviors. These effects may be, in part, a result of oxytocin's ability to attenuate hypothalamic-pituitary-adrenal (HPA) axis dysregulation. However, only one study to date has examined the effects of oxytocin on neuroendocrine reactivity or conflict resolution behavior among couples. Participants (N = 33 couples or 66 total participants) were heterosexual couples in which one or both partners endorsed substance misuse. Using a double-blind, placebo-controlled, repeated-measures design and an evidence-based behavioral coding system, we compared the impact of oxytocin (40 IU) vs. placebo on cortisol reactivity and conflict resolution behaviors. Among women, oxytocin attenuated cortisol response following the task. Oxytocin was also associated with increased Distress Maintaining Attributions and decreased Relationship Enhancing Attributions. Among men, oxytocin was associated with decreased Distress Maintaining Attributions, and both oxytocin and placebo yielded declines in Relationship Enhancing Attributions. The findings support emerging hypotheses that oxytocin may have differential effects in men and women, and indicate the need for future efforts to translate oxytocin's positive neurobiological effects into therapeutic behavioral changes.

Effects of adverse childhood experiences on the association between intranasal oxytocin and social stress reactivity among individuals with cocaine dependence

BACKGROUND

Drug dependence and adverse childhood experiences (ACE) are commonly reflected by dysregulation of the hypothalamic-pituitary-adrenal axis (HPA). Accumulating research indicates that the neuropeptide oxytocin may regulate HPA function, resulting in reductions in neuroendocrine reactivity to social stress among individuals with drug dependence. However, emerging literature suggests that individual differences may differentially impact intranasal oxytocin's effects on human social behaviors.

METHODS

This study employed a double-blind, placebo-controlled design to examine the extent to which ACE influenced the effects of intranasal oxytocin (40IU) on neuroendocrine reactivity to a laboratory social stress paradigm in a sample of 31 cocaine-dependent individuals.

RESULTS

ACE scores modified the relationship between intranasal oxytocin and cortisol reactivity. While ACE modified the relationship between intranasal oxytocin and DHEA response in a similar direction to what was seen in cortisol, it did not reach statistical significance.

CONCLUSIONS

Findings are congruent with the emerging hypothesis that intranasal oxytocin may differentially attenuate social stress reactivity among individuals with specific vulnerabilities. Future research examining the nuances of intranasal oxytocin's therapeutic potential is necessary.

Intranasal oxytocin administration prior to exposure therapy for arachnophobia impedes treatment response

BACKGROUND

Recent years have seen the emergence of a new paradigm for treatment of anxiety disorders focusing on development of drugs that facilitate psychotherapies via targeted effects on neuroplasticity. One compound that has generated interest in this regard is oxytocin (OT), a mammalian neuropeptide that modulates activity of the neurocircuit mediating fear extinction and memory processes. Recent research in healthy humans has suggested that intranasal OT administered prior to fear extinction training enhances fear extinction performance, supporting its potential to augment exposure-based psychotherapy. Here, we tested the hypothesis that OT treatment would facilitate response to exposure therapy in patients with specific phobia.

METHODS

We conducted a small proof-of-concept trial investigating the effect of pretreatment intranasal OT administration on a brief, single-session exposure treatment for arachnophobia (fear of spiders). The study was randomized, double-blind, and placebo controlled (n = 13 placebo, 11 females; n = 10 OT, 8 females) with 1-week and 1-month follow-up assessments. Dependent measures attended to arachnophobia symptoms (self-report), phobic behavior (behavioral avoidance of spider task), and treatment credibility/therapeutic alliance.

RESULTS

Administration of OT prior to exposure therapy tended to impede treatment response as measured by self-report of symptoms at both follow-up periods. OT treatment did not significantly affect behavioral measures of fear. Immediately after OT administration but before therapy, the OT group trended toward less confidence in the treatment. The OT group also trended toward lower ratings of therapeutic alliance than placebo.

CONCLUSIONS

These results suggest that OT administration effects on extinction may vary depending on conditions and population.

No evidence that MDMA-induced enhancement of emotional empathy is related to peripheral oxytocin levels or 5-HT1a receptor activation

The present study aimed at investigating the effect of MDMA on measures of empathy and social interaction, and the roles of oxytocin and the 5-HT_1A receptor in these effects. The design was placebo-controlled within-subject with 4 treatment conditions: MDMA (75 mg), with or without pindolol (20 mg), oxytocin nasal spray (40 IU+16 IU) or placebo. Participants were 20 healthy poly-drug MDMA users, aged between 18–26 years. Cognitive and emotional empathy were assessed by means of the Reading the Mind in the Eyes Test and the Multifaceted Empathy Test. Social interaction, defined as trust and reciprocity, was assessed by means of a Trust Game and a Social Ball Tossing Game. Results showed that MDMA selectively affected emotional empathy and left cognitive empathy, trust and reciprocity unaffected. When combined with pindolol, these effects remained unchanged. Oxytocin did not affect measures of empathy and social interaction. Changes in emotional empathy were not related to oxytocin plasma levels. It was concluded that MDMA (75 mg) selectively enhances emotional empathy in humans. While the underlying neurobiological mechanism is still unknown, it is suggested that peripheral oxytocin does not seem to be the main actor in this; potential candidates are the serotonin 2A and the vasopressin 1A receptors.

Trial Registration

MDMA & PSB NTR 2636

Oxytocin's role in anxiety: a critical appraisal

A growing literature suggests that the oxytocin (OT) system may play a role in human anxiety states, anxiety-related traits, and moreover, that this system may be a target for the development of novel anxiolytic treatments. However, studies of OT's acute and chronic effects on various aspects of anxiety have produced mixed results. In this forward-looking review, we discuss the myriad phenomena to which the term "anxiety" is applied in the OT literature and the problem this presents developing a coherent picture of OT's role in anxiety. We then survey several different fields of research that support the role of the OT system in human anxiety, including evolutionary perspectives, translational and neuroimaging research, genetic studies, and clinical trials of intranasal OT. As an outgrowth of this data, we propose a "bowtie" model of OT's role at the interface of social attachment and anxiety. We next direct attention to understudied brain regions and neural circuits which may be important to study in OT experiments in humans anxiety disorders. Finally, we conclude by proposing questions and priorities for studying both the clinical potential of OT in anxiety, as well as mechanisms that may underlie this potential. Crucially, these priorities include targeted proof-of-concept clinical trials of IN OT in certain anxiety disorders, including investigations of individual moderators of OT's anxiolytic effects (i.e. sex, genetic factors, and early experience). This article is part of a Special Issue entitled Oxytocin and Social Behav.

Oxytocin and psychotherapy: a pilot study of its physiological, behavioral and subjective effects in males with depression

Individual psychotherapy is an important treatment for a number of psychiatric conditions and involves a unique form of human attachment. This raises the question of whether oxytocin (OT), the paradigmatic "attachment hormone", may have benefits in this context. In this randomized, double-blind, crossover trial, we gave male psychiatric outpatients with major depressive disorder 40 IU intranasal OT or placebo before a videotaped session with a therapist and measured a number of subjective, physiological, and behavioral parameters. We report three main findings. Surprisingly - in contrast to prior reports of OT's anxiolytic properties - we found OT caused an increase in anxiety over the course of the therapy session. Secondly, though it had no main effect on cortisol, eye contact, or overall behavior, we did find that OT caused a decrease in nonverbal behaviors that cut off social contact, after controlling for level of depressive symptoms. Lastly, we replicated prior findings that OT improves social cognition (performance on the reading the mind in the eyes test (RMET)), albeit in a depressed patient group. These results inform future studies of oxytocin and psychotherapy and suggest that in certain clinical populations and contexts, OT has heterogeneous subjective effects which may include acute anxiogenesis. Moreover, the similarity of some of these acute effects to those of single-dose serotonergic antidepressants raises interesting questions about the potential antidepressant benefits of chronic OT administration.

The association between the oxytocin receptor gene (OXTR) and hypnotizability

Hypnosis has puzzled scientists for centuries, and particularly the reason why some people are prone to engaging in suggested experiences discordant with external reality. Absorption in internal experience is one key component of the hypnotic response. The neuropeptide oxytocin has been posited to heighten sensitivity to external cues, and it is possible that individual differences in oxytocin-related capacity to engage in external or internal experiences influences hypnotic response. To test this proposal, 185 Caucasian individuals provided saliva samples for analysis of polymorphisms in the oxytocin receptor gene, COMT, and independently completed standardized measures of hypnotizability and absorption. Participants with the GG genotype at rs53576 were characterized by lower hypnotizability and absorption scores than those with the A allele; there was no association between hyponotizability and COMT. These findings provide initial evidence that the capacity to respond to suggestions for altered internal experience is influenced by the oxytocin receptor gene, and is consistent with evidence that oxytocin plays an important role in modulating the extent to which people engage with external versus internal experiences.

The effect of intranasal oxytocin treatment on conditioned fear extinction and recall in a healthy human sample

RATIONALE

To improve outcomes for patients undergoing extinction-based therapies (e.g., exposure therapy) for anxiety disorders such as post-traumatic stress disorder (PTSD), there has been interest in identifying pharmaceutical compounds that might facilitate fear extinction learning and recall. Oxytocin (OT) is a mammalian neuropeptide that modulates activation of fear extinction-based neural circuits and fear responses. Little is known, however, about the effects of OT treatment on conditioned fear responding and extinction in humans.

OBJECTIVES

The purpose of the present study was to assess the effects of OT in a fear-potentiated startle task of fear conditioning and extinction.

METHODS

A double-blind, placebo-controlled study of 44 healthy human participants was conducted. Participants underwent a conditioned fear acquisition procedure, after which they were randomized to treatment group and delivered OT (24 IU) or placebo via intranasal (IN) spray. Forty-five minutes after treatment, participants underwent extinction training. Twenty-four hours later, subjects were tested for extinction recall.

RESULTS

Relative to placebo, the OT group showed increased fear-potentiated startle responding during the earliest stage of extinction training relative to placebo; however, all treatment groups showed the same level of reduced responding by the end of extinction training. Twenty-four hours later, the OT group showed significantly higher recall of extinction relative to placebo.

CONCLUSIONS

The current study provides preliminary evidence that OT may facilitate fear extinction recall in humans. These results support further study of OT as a potential adjunctive treatment for extinction-based therapies in fear-related disorders.