The 3,4-methylenedioxymethamphetamine enhances early visual processing for salient socio-emotional stimuli.

The 3,4-methylenedioxymethamphetamine (MDMA) has long been used non-medically, and it is currently under investigation for its potential therapeutic benefits. Both uses may be related to its ability to enhance empathy, sociability, emotional processing and its anxiolytic effects. However, the neural mechanisms underlying these effects, and their specificity to MDMA compared to other stimulants, are not yet fully understood. Here, using electroencephalography (EEG), we investigated the effects of MDMA and a prototypic stimulant, methamphetamine (MA), on early visual processing of socio-emotional stimuli in an oddball emotional faces paradigm. Specifically, we examined whether MDMA or MA enhance the processing of facial expressions, compared to placebo, during the early stages of visual perception. MDMA enhanced an event-related component that is sensitive to detecting faces (N170), specifically for happy and angry expressions compared to neutral faces. MA did not affect this measure, and neither drug altered other components of the response to emotional faces. These findings provide novel insights into the neural mechanisms underlying the effects of MDMA on socio-emotional processing and may have implications for the therapeutic use of MDMA in the treatment of social anxiety and other psychiatric disorders.

Effects of Intranasal Oxytocin on Stress-Induced Cigarette Craving in Daily Smokers.

BACKGROUND: Cigarette smoking is a well-known public health concern, and there is an urgent need to develop new treatments to reduce smoking or facilitate abstinence. One factor that is known to contribute to relapse is stress, making the stress response an important target for treatment. The neuropeptide oxytocin (OT) is believed to have stress-reducing effects, and in addition there is evidence that it reduces drug craving. The purpose of the present study was to examine the effects of intranasal OT on stress-induced cigarette craving in regular smokers after 12 h of abstinence. METHOD: Daily smokers (n = 48) completed a stress induction task and a nonstressful control task at two different sessions, receiving intranasal OT (40 IU) or placebo (PBO) before or after the task. Subjects were randomly assigned to one of three groups: Group PP (n = 16) received PBO before and after the stress/control tasks, Group OP (n = 16) received OT before the tasks and PBO after, and Group PO (n = 16) received PBO before the tasks and OT shortly after completing the tasks. Cigarette craving as well as subjective and physiological responses to stress was assessed. RESULTS: OT did not alter responses to stress, whether it was administered before or after the stressful task, on measures of cigarette craving, anxiety, heart rate, blood pressure, and cortisol levels. CONCLUSIONS: The current study findings do not support several previous reports that OT reduced either stress or drug craving. IMPLICATIONS: This study finds a null result of the neuropeptide oxytocin on stress-induced cigarette craving. Reporting null findings is part of the process of identifying potential treatments for addictive disorders.

Effects of Buprenorphine on Responses to Emotional Stimuli in Individuals with a Range of Mood Symptomatology.

Background: The opioid drug buprenorphine has been shown to modify responses to emotional stimuli and may have antidepressant properties. In preclinical studies, it shows antidepressant-like and anxiolytic-like effects, and a handful of clinical studies suggest it may reduce symptoms of depression in patients. We have shown that low doses of buprenorphine reduce responses to negative emotional stimuli in healthy adults. Here we extended these findings to individuals with symptoms of depression and anxiety. Methods: We examined the effects of buprenorphine on attention to emotional facial expressions and ratings of and psychophysiological responses to emotional images in adults with a range of mood symptomatology. Volunteers (n=38) were recruited with low, mild, moderate, and severe scores on the Depression-Anxiety-Stress Scale. They attended 2 laboratory sessions during which they received either placebo or 0.2 mg sublingual buprenorphine in randomized order under double-blind conditions. During peak drug effect, participants completed a visual attention task assessing responses to emotional faces and a picture-rating task assessing responses to emotional images with and without social content. Results: Buprenorphine reduced attention to fearful facial expressions as it did in our previous study, and the emotion-specific effect was especially pronounced in individuals with high Depression-Anxiety-Stress Scale scores. The drug also increased ratings of positivity of images with social content, but this effect was less strong in individuals with higher Depression-Anxiety-Stress Scale scores. Conclusions: These results suggest low doses of buprenorphine may reduce some dimensions of responses to negative emotional stimuli in individuals high on depression or anxiety, while leaving other dimensions unaffected.

Effects of opioid- and non-opioid analgesics on responses to psychosocial stress in humans.

Both preclinical and clinical evidence suggests that the endogenous opioid system is involved in responses to stress. For example, in animal models opioid agonists reduce isolation distress whereas opioid antagonists increase isolation distress. We recently reported that the mixed mu agonist and kappa antagonist buprenorphine dampened responses to acute psychosocial stress in humans. Now we extend this to study the effects of a pure mu-opioid agonist, hydromorphone, and a non-opioid analgesic, acetaminophen, on response to social stress. We compared the effect of hydromorphone (2 and 4 mg), acetaminophen (1000 mg) to a placebo using a between subject design. Healthy adult volunteers were randomly assigned to receive placebo (N = 13), 2 mg hydromorphone (N = 12), 4 mg hydromorphone (N = 12), or 1000 mg acetaminophen (paracetamol; N = 13) under double-blind conditions before undergoing a stress task or a control task on two separate sessions. The stress task, consisting of a standardized speaking task and the non-stressful control task were presented in counterbalanced order. Dependent measures included mood ratings, subjective appraisal of the stress (or no-stress) task, salivary cortisol, pupil diameter, heart rate, and blood pressure. The stress task produced its expected increase in heart rate, blood pressure, salivary cortisol, pupil diameter, and subjective ratings of anxiety and negative mood. Hydromorphone dose-dependently dampened cortisol responses to stress, and decreased ratings of how "challenging" participants found the task. Acetaminophen did not affect physiological responses, but, like hydromorphone, decreased ratings of how "challenging" the task was. The hydromorphone results support the idea that the mu-opioid system is involved in physiological responses to acute stress in humans, in line with results from preclinical studies. The non-opioid analgesic acetaminophen did not dampen physiological responses, but did reduce some components of psychological stress. It remains to be determined how both opioid and non-opioid systems mediate the complex physiological and psychological responses to social stress.

Effects of acute doses of prosocial drugs methamphetamine and alcohol on plasma oxytocin levels.

Many drugs, including alcohol and stimulants, demonstrably increase sociability and verbal interaction and are recreationally consumed in social settings. One drug, 3,4-methylenedioxymethamphetamine (MDMA, ecstasy), seems to produce its prosocial effects by increasing plasma oxytocin levels, and the oxytocin system has been implicated in responses to several other drugs of abuse. Here, we sought to investigate the effects of 2 other "social" drugs on plasma oxytocin levels--methamphetamine and alcohol. Based on their shared capacity to enhance sociability, we hypothesized that both methamphetamine and alcohol would increase plasma oxytocin levels. In study 1, 11 healthy adult volunteers attended 3 sessions during which they received methamphetamine (10 mg or 20 mg) or placebo under double-blind conditions. Subjective drug effects, cardiovascular effects, and plasma oxytocin levels were measured at regular intervals throughout the sessions. In study 2, 8 healthy adult volunteers attended a single session during which they received 1 beverage containing placebo, and then a beverage containing alcohol (0.8 g/kg). Subjective effects, breath alcohol levels, and plasma oxytocin levels were measured at regular intervals. Both methamphetamine and alcohol produced their expected physiological and subjective effects, but neither of these drugs increased plasma oxytocin levels. The neurobiological mechanisms mediating the prosocial effects of drugs such as alcohol and methamphetamine remain to be identified.

Drug effects on responses to emotional facial expressions: recent findings.

Many psychoactive drugs increase social behavior and enhance social interactions, which may, in turn, increase their attractiveness to users. Although the psychological mechanisms by which drugs affect social behavior are not fully understood, there is some evidence that drugs alter the perception of emotions in others. Drugs can affect the ability to detect, attend to, and respond to emotional facial expressions, which in turn may influence their use in social settings. Either increased reactivity to positive expressions or decreased response to negative expressions may facilitate social interaction. This article reviews evidence that psychoactive drugs alter the processing of emotional facial expressions using subjective, behavioral, and physiological measures. The findings lay the groundwork for better understanding how drugs alter social processing and social behavior more generally.

Social homeostasis and psychoactive drugs: What can we learn from opioid and amphetamine drug challenge studies in humans?

BACKGROUND: Social disequilibrium, or disrupted social homeostasis, underlies many behavioral disorders, including problematic drug use. One way to study the relationship between drug use and social homeostasis is to determine whether single doses of psychoactive drugs relieve some of the discomfort of social isolation and promote social connection. METHODS: In this narrative review, we discuss challenges and opportunities in studying the relationship between psychoactive drugs and social homeostasis. Using the examples of opioids and amphetamines, we discuss the evidence that drugs alleviate dysphoria related to lack of social connection or produce pro-social effects that improve connection. RESULTS: With regard to opioid drugs, we report that mu opioid agonists and kappa opioid antagonists reduce distress from social isolation, and mu opioid agonists enhance social reward. Amphetamine-like stimulant drugs, including MDMA, do not seem to act by reducing the distress of social isolation, but they have notable prosocial effects that increase both motivation for social contact and the pleasure derived from interacting socially. CONCLUSIONS: Many questions remain in understanding interactions between drugs and social equilibrium, including whether these effects contribute to problematic drug use. We identify gaps in knowledge, including the effects of drug withdrawal or dependence on social function, or the responses of individuals with psychiatric symptomatology. Understanding these actions on social processes will help to develop novel pharmacologic treatments for clinical problems related to social disequilibrium.

Altered States and Social Bonds: Effects of MDMA and Serotonergic Psychedelics on Social Behavior as a Mechanism Underlying Substance-Assisted Therapy.

There has been renewed interest in the use of 3,4-methylenedioxy-methamphetamine (MDMA) and serotonergic psychedelics in the treatment of multiple psychiatric disorders. Many of these compounds are known to produce prosocial effects, but how these effects relate to therapeutic efficacy and the extent to which prosocial effects are unique to a particular drug class is unknown. In this article, we present a narrative overview and compare evidence for the prosocial effects of MDMA and serotonergic psychedelics to elucidate shared mechanisms that may underlie the therapeutic process. We discuss 4 categories of prosocial effects: altered self-image, responses to social reward, responses to negative social input, and social neuroplasticity. While both categories of drugs alter self-perception, MDMA may do so in a way that is less related to the experience of mystical-type states than serotonergic psychedelics. In the case of social reward, evidence supports the ability of MDMA to enhance responses and suggests that serotonergic psychedelics may also do so, but more research is needed in this area. Both drug classes consistently dampen reactivity to negative social stimuli. Finally, preclinical evidence supports the ability of both drug classes to induce social neuroplasticity, promoting adaptive rewiring of neural circuits, which may be helpful in trauma processing. While both MDMA and serotonergic psychedelics produce prosocial effects, they differ in the mechanisms through which they do this. These differences affect the types of psychosocial interventions that may work best with each compound.

MDMA enhances positive affective responses to social feedback.

BACKGROUND: The prosocial compound ± 3,4-methylenedioxymethamphetamine (MDMA) is an amphetamine derivative that has shown promise as an adjunct to psychotherapy in the treatment of post-traumatic stress disorder. MDMA increases positive responses to social images, and it has been suggested that the ability of MDMA to positively bias social perception may underlie its therapeutic efficacy as a psychotherapy adjunct. However, the effect of the compound on affective responses to positive or negative social feedback has not been tested. AIMS: In this study, we aimed to test the effects of MDMA compared to placebo and the prototypical stimulant, methamphetamine (MA), on responses to positive and negative social feedback. METHODS: This was a double-blind, placebo-controlled, crossover trial (NCT03790618), comparing the effects of two doses of MDMA (0.75 mg/kg, 1.5 mg/kg) to both placebo and MA (20 mg) on responses to a personalized social feedback task, similar to a dating app, in healthy adult volunteers ages 18-40 (N = 36, 18 women, 18 men). RESULTS/OUTCOMES: The high dose of MDMA increased positive affective responses to social feedback. CONCLUSIONS/INTERPRETATIONS: These findings suggest one process by which MDMA may facilitate social connection. Further work is needed to understand how MDMA affects responses to more generalized types of social feedback and to understand these effects in clinical populations.

Social Psychopharmacology: Novel Approaches to Treat Deficits in Social Motivation in Schizophrenia.

BACKGROUND AND HYPOTHESIS: Diminished social motivation is a negative symptom of schizophrenia and leads to severe functional consequences for many patients suffering from the illness. However, there are no effective medications available to treat this symptom. Despite the lack of approved treatments for patients, there is a growing body of literature on the effects of several classes of drugs on social motivation in healthy volunteers that may be relevant to patients. The aim of this review is to synthesize these results in an effort to identify novel directions for the development of medications to treat reduced social motivation in schizophrenia. STUDY DESIGN: In this article, we review pharmacologic challenge studies addressing the acute effects of psychoactive drugs on social motivation in healthy volunteers and consider how these findings may be applied to deficits in social motivation in schizophrenia. We include studies testing amphetamines and 3,4-methylenedioxymethamphetamine (MDMA), opioids, cannabis, serotonergic psychedelics, antidepressants, benzodiazepines, and neuropeptides. STUDY RESULTS: We report that amphetamines, MDMA, and some opioid medications enhance social motivation in healthy adults and may represent promising avenues of investigation in schizophrenia. CONCLUSIONS: Given the acute effects of these drugs on behavioral and performance-based measures of social motivation in healthy volunteers, they may be particularly beneficial as an adjunct to psychosocial training programs in patient populations. It remains to be determined how these medications affect patients with deficits in social motivation, and in which contexts they may be most effectively administered.

Challenges in translational research: MDMA in the laboratory versus therapeutic settings.

Despite substantial progress in the use of mind-altering drugs to treat psychiatric disorders, the psychological processes through which these drugs change mood or behavior are poorly understood. Controlled laboratory studies with well-defined psychological constructs are valuable to understand how these drugs manifest their therapeutic benefit. However, there are substantial methodological differences between clinical studies investigating therapeutic outcome and laboratory studies investigating the processes that might underlie the therapeutic effects. Here, we examine some of these differences using the example of 3,4-methylenedioxymethamphetamine (MDMA). We review differences in expectancies, social and physical context, participant characteristics, pharmacological factors, and outcome measures in studies with participants who do or do not have psychiatric diagnoses. We describe the challenges and opportunities in translating findings from laboratory studies to the clinic and identify ways to bridge the gap between these approaches.

Effects of Acute Drug Administration on Emotion: A Review of Pharmacological MRI Studies.

PURPOSE OF REVIEW: Many drug users claim to use drugs to cope with negative emotions, which may, in turn, result in persistent emotional blunting or anhedonia even when they are not using drugs. The purpose of this review is to describe the ways acute administration of psychoactive drugs impacts brain regions during emotion-related tasks, as a first step in understanding how drugs influence emotion processing in the brain. RECENT FINDINGS: Drugs have varying effects on neural responses to emotional stimuli. In general, alcohol, analgesics, and psychedelics reduce neural reactivity to negative emotional stimuli in the amygdala and other brain regions. Other drugs produce mixed effects: Stimulants such as caffeine and modafinil increase brain activation while viewing emotional stimuli, whereas MDMA decreases activation during presentation of negative images. The effects of cannabinoids (cannabidiol and THC) are mixed. There are also inconsistent findings on the associations between neural responses to emotional stimuli and subjective drug effects. SUMMARY: Consistent with the notion that individuals might use drugs non-medically to diminish the experience of negative emotions, several drugs of abuse decrease neural responses to negative stimuli in limbic brain regions. These neural actions may underlie the reported 'emotional blunting' of drugs, which may contribute to drug-seeking behavior. Future work is needed to examine these limbic responses in relation to self-reports of changes in affect, both during acute administration and after extended drug use.

Preliminary Report on the Effects of a Low Dose of LSD on Resting-State Amygdala Functional Connectivity.

BACKGROUND: The practice of "microdosing," or the use of repeated, very low doses of lysergic acid diethylamide (LSD) to improve mood or cognition, has received considerable public attention, but empirical studies are lacking. Controlled studies are needed to investigate both the therapeutic potential and the neurobiological underpinnings of this pharmacologic treatment. METHODS: The present study was designed to examine the effects of a single low dose of LSD (13 µg) versus placebo on resting-state functional connectivity and cerebral blood flow in healthy young adults. Twenty men and women, 18 to 35 years old, participated in 2 functional magnetic resonance imaging scanning sessions in which they received placebo or LSD under double-blind conditions. During each session, the participants completed drug effect and mood questionnaires, and physiological measures were recorded. During expected peak drug effect, they underwent resting-state blood oxygen level-dependent and arterial spin labeling scans. Cerebral blood flow as well as amygdala and thalamic connectivity were analyzed. RESULTS: LSD increased amygdala seed-based connectivity with the right angular gyrus, right middle frontal gyrus, and the cerebellum, and decreased amygdala connectivity with the left and right postcentral gyrus and the superior temporal gyrus. This low dose of LSD had weak and variable effects on mood, but its effects on positive mood were positively correlated with the increase in amygdala-middle frontal gyrus connectivity strength. CONCLUSIONS: These preliminary findings show that a very low dose of LSD, which produces negligible subjective changes, alters brain connectivity in limbic circuits. Additional studies, especially with repeated dosing, will reveal whether these neural changes are related to the drug's purported antidepressant effect.

Acute Subjective and Behavioral Effects of Microdoses of Lysergic Acid Diethylamide in Healthy Human Volunteers.

BACKGROUND: Numerous anecdotal reports suggest that repeated use of very low doses of lysergic acid diethylamide (LSD), known as microdosing, improves mood and cognitive function. These effects are consistent both with the known actions of LSD on serotonin receptors and with limited evidence that higher doses of LSD (100-200 µg) positively bias emotion processing. Yet, the effects of such subthreshold doses of LSD have not been tested in a controlled laboratory setting. As a first step, we examined the effects of single very low doses of LSD (0-26 µg) on mood and behavior in healthy volunteers under double-blind conditions. METHODS: Healthy young adults (N = 20) attended 4 laboratory sessions during which they received 0 (placebo), 6.5, 13, or 26 µg of LSD in randomized order at 1-week intervals. During expected peak drug effect, they completed mood questionnaires and behavioral tasks assessing emotion processing and cognition. Cardiovascular measures and body temperature were also assessed. RESULTS: LSD produced dose-related subjective effects across the 3 doses (6.5, 13, and 26 µg). At the highest dose, the drug also increased ratings of vigor and slightly decreased positivity ratings of images with positive emotional content. Other mood measures, cognition, and physiological measures were unaffected. CONCLUSIONS: Single microdoses of LSD produced orderly dose-related subjective effects in healthy volunteers. These findings indicate that a threshold dose of 13 µg of LSD might be used safely in an investigation of repeated administrations. It remains to be determined whether the drug improves mood or cognition in individuals with symptoms of depression.

Effects of MDMA on attention to positive social cues and pleasantness of affective touch.

The psychostimulant drug ±3,4-methylenedioxymethamphetamine (MDMA) reportedly produces distinctive feelings of empathy and closeness with others. MDMA increases social behavior in animal models and has shown promise in psychiatric disorders, such as autism spectrum disorder (ASD) and post-traumatic stress disorder (PTSD). How it produces these prosocial effects is not known. This behavioral and psychophysiological study examined the effects of MDMA, compared with the prototypical stimulant methamphetamine (MA), on two measures of social behavior in healthy young adults: (i) responses to socially relevant, "affective" touch, and (ii) visual attention to emotional faces. Men and women (N = 36) attended four sessions in which they received MDMA (0.75 or 1.5 mg/kg), MA (20 mg), or a placebo in randomized order under double-blind conditions. Responses to experienced and observed affective touch (i.e., being touched or watching others being touched) were assessed using facial electromyography (EMG), a proxy of affective state. Responses to emotional faces were assessed using electrooculography (EOG) in a measure of attentional bias. Subjective ratings were also included. We hypothesized that MDMA, but not MA, would enhance the ratings of pleasantness and psychophysiological responses to affective touch and increase attentional bias toward positive facial expressions. Consistent with this, we found that MDMA, but not MA, selectively enhanced ratings of pleasantness of experienced affective touch. Neither drug altered the ratings of pleasantness of observed touch. On the EOG measure of attentional bias, MDMA, but not MA, increased attention toward happy faces. These results provide new evidence that MDMA can enhance the experience of positive social interactions; in this case, pleasantness of physical touch and attentional bias toward positive facial expressions. The findings are consistent with evidence that the prosocial effects are unique to MDMA relative to another stimulant. Understanding the behavioral and neurobiological processes underlying the distinctive social effects of MDMA is a key step to developing the drug for psychiatric disorders.

Developmental autonomy and somatic niche construction promotes robust cell fate decisions.

During the course of development cells undergo division producing a variety of cell types. Proliferation and differentiation are dependent on both genetic programs, encoded by the cellular genome, and environmental cues produced by the local cellular environment imposing local selection pressures on cells. We explore the role that cellular signals play over a large range of potential parameter regimes, in minimizing developmental error: errors in differentiation where an inappropriate proportion of differentiated daughter cells are generated. We find that trophic factors produced by the population of dividing cells can compensate for increased error rates when signals act through a form of positive feedback--survival signals. We operationalize these signals as the somatic niche and refer to their production as somatic niche construction. We find that tissue development switches to an autonomous state, independent of cellular signals, when errors are unmanageably high or density regulation is very strong. A signal-selective regime--strong niche dependence--is favored at low to intermediate error, assuming compartmentalized density dependence.

MDMA does not alter responses to the Trier Social Stress Test in humans.

RATIONALE: ±3,4-Methylenedioxymethamphetamine (MDMA, "ecstasy") is a stimulant-psychedelic drug with unique social effects. It may dampen reactivity to negative social stimuli such as social threat and rejection. Perhaps because of these effects, MDMA has shown promise as a treatment for post-traumatic stress disorder (PTSD). However, the effect of single doses of MDMA on responses to an acute psychosocial stressor has not been tested. OBJECTIVES: In this study, we sought to test the effects of MDMA on responses to stress in healthy adults using a public speaking task. We hypothesized that the drug would reduce responses to the stressful task. METHODS: Volunteers (N = 39) were randomly assigned to receive placebo (N = 13), 0.5 mg/kg MDMA (N = 13), or 1.0 mg/kg MDMA (N = 13) during a stress and a no-stress session. Dependent measures included subjective reports of drug effects and emotional responses to the task, as well as salivary cortisol, heart rate, and blood pressure. RESULTS: The stress task produced its expected increase in physiological responses (cortisol, heart rate) and subjective ratings of stress in all three groups, and MDMA produced its expected subjective and physiological effects. MDMA alone increased ratings of subjective stress, heart rate, and saliva cortisol concentrations, but contrary to our hypothesis, it did not moderate responses to the Trier Social Stress Test. CONCLUSIONS: Despite its efficacy in PTSD and anxiety, MDMA did not reduce either the subjective or objective responses to stress in this controlled study. The conditions under which MDMA relieves responses to negative events or memories remain to be determined.

Pharmacological challenge studies with acute psychosocial stress.

Chronic stress is known to affect many psychiatric disorders, and studies of responses to acute stress may reveal processes that ultimately lead to maladaptive responses to chronic stress. Many studies have used simulated public speaking tasks to induce stress in the laboratory and, of interest to this review, the tasks have been used to assess the effects of both therapeutic and nonmedical drugs on stress reactivity. Here we review 38 studies that examined effects of single doses of drugs on subjective, cardiovascular and hormonal responses to an acute social stressor in healthy volunteers. Most studies have used the Trier Social Stress Test (TSST), or variations on it involving public speaking or mental arithmetic. Pharmacological studies with the TSST (ph-TSST) have been conducted for three main reasons: i) to determine the clinical effectiveness of psychiatric medications to reduce stress responses, ii) to investigate the neurochemical mechanisms involved in the stress response, and iii) to determine whether drugs of abuse relieve, or occasionally worsen, responses to acute stress. The review indicates that standard anxiolytic medications consistently reduce subjective responses to the TSST, whereas single doses of antidepressants produce mixed effects. Mechanistic studies indicate that several neurotransmitter systems are involved in the stress response, including serotonin, norepinephrine, GABA, glutamate, opioids, and endocannabinoids. Among drugs of abuse, alcohol and cannabinoids exert some stress-dampening effects, whereas caffeine, nicotine, and amphetamines tend to increase stress responses. Comparing outcome measures of the responses to stress, subjective ratings of anxiety are among the most sensitive indices of the stress response, with cortisol levels second and cardiovascular responses least sensitive. We conclude that the TSST is a valuable tool to study the clinical effectiveness of medications for stress-related disorders, and that it is important to use standardized procedures to enable comparisons across studies.

Effects of d-amphetamine upon psychosocial stress responses.

Psychostimulant drugs alter the salience of stimuli in both laboratory animals and humans. In animals, stimulants increase rates of responding to conditioned incentive stimuli, and in humans, amphetamine increases positive ratings of emotional images. However, the effects of stimulants on real-life emotional events have not been studied in humans. In this study, we examined the effect of d-amphetamine on responses to acute psychosocial stress using a public speaking task. Healthy volunteers (N=56) participated in two experimental sessions, one with a psychosocial stressor (the Trier Social Stress Test) and one with a non-stressful control task. They were randomly assigned to receive d-amphetamine (5 mg n=18, 10 mg n=20) or placebo (n=18) on both sessions under double blind conditions. Salivary cortisol, subjective mood, and vital signs were measured at regular intervals during the session. Subjects also provided cognitive appraisals of the tasks before and after their performances. Amphetamine produced its expected mood and physiological effects, and the Trier Social Stress Test produced its expected effects on cortisol and mood. Although neither dose of amphetamine altered cardiovascular or hormonal responses to stress, amphetamine (10 mg) increased participants' pre-task appraisals of how challenging the task would be, and it increased post-task ratings of self-efficacy. Paradoxically, it also increased ratings of how stressful the task was, and prolonged aversive emotional responses. These findings suggest that amphetamine differentially affects stress response components: it may increase participants' appraisals of self-efficacy without dampening the direct emotional or physiological responses to the stress.