Comparing Drinking Game Motives, Behaviors, and Consequences Among Varsity Athletes, Recreational Athletes, and Non-Student-Athletes: A Multisite University Study.

OBJECTIVE: Among college students, student-athletes are at increased risk for heavy alcohol consumption, participation in risky drinking practices (e.g., playing drinking games [DG]), and adverse alcohol-related consequences relative to non-student-athletes. Within the student-athlete population, level of sports participation (e.g., recreational or varsity sports) can affect alcohol use behaviors and consequences, but our understanding of the extent to which level of sports participation influences engagement in DG is limited. Thus, in the present study, we examined differences in frequency of participation in DG, typical drink consumption while playing DG, negative DG consequences, and motives for playing DG among varsity, recreational, and non-student-athletes. METHOD: College students (n = 7,901 across 12 U.S. colleges/universities) completed questionnaires on alcohol use attitudes, behaviors, and consequences. RESULTS: Student-athletes (recreational or varsity sports) were more likely to have participated in DG within the past month than non-student-athletes. Among students who reported past-month DG play, recreational athletes played more often and endorsed more enhancement/thrills motives for playing DG than non-student-athletes, and student-athletes (recreational or varsity) endorsed higher levels of competition motives for playing DG than non-student-athletes. CONCLUSIONS: These findings shed light on some risky drinking patterns and motives of recreational athletes who are often overlooked and under-resourced in health research and clinical practice. Recreational and varsity student-athletes could benefit from alcohol screening and prevention efforts, which can include provision of competitive and alcohol-free social activities and promotion of alcohol protective behavioral strategies to help reduce recreational athletes' risk for harm while playing DG.

Establishing the Roles of the Dorsal and Ventral Striatum in Humor Comprehension and Appreciation with fMRI.

Humor comprehension (i.e., getting a joke) and humor appreciation (i.e., enjoying a joke) are distinct, cognitively complex processes. Functional magnetic resonance imaging (fMRI) investigations have identified several key cortical regions but have overlooked subcortical structures that have theoretical importance in humor processing. The dorsal striatum (DS) contributes to working memory, ambiguity processing, and cognitive flexibility, cognitive functions that are required to accurately recognize humorous stimuli. The ventral striatum (VS) is critical in reward processing and enjoyment. We hypothesized that the DS and VS play important roles in humor comprehension and appreciation, respectively. We investigated the engagement of these regions in these distinct processes using fMRI. Twenty-six healthy young male and female human adults completed two humor-elicitation tasks during a 3 tesla fMRI scan consisting of a traditional behavior-based joke task and a naturalistic audiovisual sitcom paradigm (i.e., Seinfeld viewing task). Across both humor-elicitation methods, whole-brain analyses revealed cortical activation in the inferior frontal gyrus, the middle frontal gyrus, and the middle temporal gyrus for humor comprehension, and the temporal cortex for humor appreciation. Additionally, with region of interest analyses, we specifically examined whether DS and VS activation correlated with these processes. Across both tasks, we demonstrated that humor comprehension implicates both the DS and the VS, whereas humor appreciation only engages the VS. These results establish the role of the DS in humor comprehension, which has been previously overlooked, and emphasize the role of the VS in humor processing more generally.SIGNIFICANCE STATEMENT Humorous stimuli are processed by the brain in at least two distinct stages. First, humor comprehension involves understanding humorous intent through cognitive and problem-solving mechanisms. Second, humor appreciation involves enjoyment, mirth, and laughter in response to a joke. The roles of smaller subcortical brain regions in humor processing, such as the DS and VS, have been overlooked in previous investigations. However, these regions are involved in functions that support humor comprehension (e.g., working memory ambiguity resolution, and cognitive flexibility) and humor appreciation (e.g., reward processing, pleasure, and enjoyment). In this study, we used neuroimaging to demonstrate that the DS and VS play important roles in humor comprehension and appreciation, respectively, across two different humor-elicitation tasks.

A national study on pregaming motives, frequency, consumption, and negative alcohol consequences among university students in the United States.

BACKGROUND: Pregaming, or drinking before going out, is a commonly practiced risky behavior. Drinking motives are well-established predictors of alcohol use and negative alcohol consequences. Given the influence of context on drinking practices, motives specific to pregaming may affect pregaming behaviors and outcomes above and beyond general drinking motives. Thus, we examined how pregaming motives are related to pregaming behaviors and negative alcohol consequences. METHODS: Using data from two national cross-sectional online studies, the current study included undergraduates who pregamed at least once in the past month (n=10,200, Mage=19.9, women=61%, white=73.6%; 119 U.S. universities). Participants completed assessments of demographics, general drinking motives, pregaming motives, pregaming frequency/consumption, and negative alcohol consequences. Data were analyzed using hierarchical linear models accounting for nesting of participants within sites. RESULTS: When controlling for demographic factors and general drinking motives, interpersonal enhancement motives and intimate pursuit motives were positively associated with pregaming frequency, pregaming consumption, and negative alcohol consequences. Situational control motives were negatively associated with pregaming consumption and negative alcohol consequences. Barriers to consumption motives were negatively associated with pregaming frequency but positively associated with negative alcohol consequences. CONCLUSIONS: Students who pregame to make the night more fun or to meet potential dating partners appear to be at particular risk for negative alcohol consequences. Motives may be modifiable, particularly via cognitive/behavioral strategies. Findings suggest that specific motives may be appropriate intervention targets when trying to reduce pregaming behaviors and negative alcohol consequences.

Prologue to the special issue on predrinking and drinking game behaviors among adolescents and young adults in the United States and across the globe: Definitions and overview of prevalence rates.

Predrinking and drinking games (DGs) are common risky drinking practices among adolescents and young adults in many different countries around the world. However, most studies on these behaviors have been conducted with university student samples in a limited number of countries. Despite the risks of negative alcohol-related consequences associated with predrinking and DGs, these activities are quite prevalent among young people. In this prologue, we provide definitions for predrinking and DGs and an extensive overview of the known prevalence rates of predrinking and DGs among young people around the world. This special issue addresses known gaps in the literature by including articles which (a) use differing methodologies to examine predrinking or DGs behavior, (b) consider psychosocial and contextual factors that influence these behaviors, and (c) examine young people's perceptions of alcohol policies and interventions. Taken together this Special Issue offers an international view on how and why young people around the world engage in these risky drinking practices, and potential ways to address these behaviors.

Examining the Drinking Motives Questionnaire-Revised Short Form among university students in Australia, New Zealand and Argentina.

INTRODUCTION: The Drinking Motives Questionnaire-Revised Short Form (DMQ-R-SF) is widely used among alcohol researchers studying adolescents and young adults. The psychometric properties of the DMQ-R-SF have been examined among university students in many countries, but to our knowledge, not in Australia, New Zealand or Argentina. We sought to examine the reliability and endorsement of the items on the DMQ-R-SF, and test the associations between the DMQ-R-SF subscales and alcohol use, and negative alcohol consequences between university students from Australia, New Zealand and Argentina. METHOD: University students (N = 820) in Australia (n = 315), New Zealand (n = 265) and Argentina (n = 240) completed a confidential online alcohol survey which included the DMQ-R-SF, the Daily Drinking Questionnaire and the Brief Young Adult Alcohol Consequences Questionnaire. RESULTS: Using the alignment method, support for the four-factor model on the DMQ-R-SF emerged and the factor loadings for 11 of the 12 items were invariant across sites. Most items (8 out of 12) on the DMQ-R-SF were fully invariant across all sites, but some small differences in item reliability for one item, and endorsement for three items emerged between the sites. Across the three countries, coping motives were positively correlated with negative alcohol consequences. Enhancement motives were positively associated with both alcohol use and negative alcohol consequences among students from Australia and New Zealand. DISCUSSION AND CONCLUSIONS: Most items on the DMQ-R-SF were comparably reliable among the university students sampled from Australia, New Zealand and Argentina. Our preliminary findings suggest that the DMQ-R-SF can be reliably used with university students from these countries.

Effects of Methamphetamine on Within- and Between-Network Connectivity in Healthy Adults.

Methamphetamine (MA) abuse remains an urgent public health problem. Understanding how the drug affects brain function will help to identify how it leads to abuse and dependence. Previous studies indicate that MA and other stimulants have complex effects on resting state functional connectivity. Here, we used a hypothesis-free approach to examine the acute effects of MA (20 mg oral) versus placebo on neural connectivity in healthy adults. Using networks identified by an independent component analysis with placebo data, we examined the effects of MA on connectivity within and between resting state networks. The drug did not significantly alter connectivity within networks. MA did alter connectivity between some networks: it increased connectivity between both the thalamus and cerebellum to sensorimotor and middle temporal gyrus. However, MA decreased connectivity between sensorimotor and middle temporal gyrus networks. MA produced its expected subjective effects, but these were not significantly related to connectivity. The findings extend our knowledge of how MA affects connectivity, by reporting that it affects between-network connectivity but not within-network connectivity. Future studies with other behavioral measures may reveal relationships between the neural and behavioral actions of the drug.

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.

Participation in Drinking Games and Predrinking Among University Students in Argentina, Australia, Canada, and New Zealand.

AIMS: The limited existing research on drinking games and predrinking among university students in Argentina, Australia, Canada, and New Zealand suggests that participation in these risky drinking practices is relatively widespread among this population. Drinking norms and alcohol use can vary across countries and in different regions of the globe. The measurement of drinking games and predrinking participation between studies also differs, making cross-country comparisons difficult. The present study explored differences in past month participation in drinking games and predrinking among university students from a large public university in Argentina, Australia, Canada, and New Zealand. METHODS: The data analytic sample consisted of 1134 university students (ages 18-25, Mage = 20.2 years; 72.6% women) from Argentina (n = 349), Australia (n = 280), Canada (n = 262), and New Zealand (n = 243) who reported weekly alcohol consumption. Students completed a confidential survey on drinking attitudes and behaviors. RESULTS: Controlling for age, gender, and weekly drink consumption, there were no cross-country differences in past month participation in predrinking. In contrast, university students from Canada and New Zealand were more likely to have played a drinking game in the past month than students from Australia and Argentina. CONCLUSIONS: The present finding suggest that university students from Argentina, Australia, Canada, and New Zealand are equally likely to participate in predrinking regardless of country; however, the likelihood of playing drinking games differs as a function of country site.

Quantitative meta-analysis of heart rate variability finds reduced parasympathetic cardiac tone in women compared to men during laboratory-based social stress.

Heart rate variability (HRV) is the inter-beat interval variation between consecutive heartbeats and an autonomic reflection of emotional regulatory abilities to flexibly respond to challenges, such as psychosocial stress. Whereas there are known sex differences in stress-induced hormonal and emotional responses, we identified a gap in our understanding of sex-specific autonomic cardiac control during stress. Thus, we assessed HRV prior to, during and after administration of a public speech task in healthy participants (n = 929) according to sex. Our meta-analysis found that during stress, women had lower HRV than men, with an overall Hedges' g of 0.29 (p < 0.0001) and 0.29 (p = 0.0003) for fixed and random effects models, respectively. We did not find significant heterogeneity or evidence of publication bias. Analyses of additional timepoints showed no baseline difference and marginally lower HRV in women during anticipation and recovery. Findings of the present meta-analysis confirm sex differences in stress-induced hyperarousal and form a justification for implementation of mechanistic studies evaluating gonadal hormones, their potent metabolites and pro-inflammatory cytokines as mediators of this relationship.

Social Symptoms of Parkinson's Disease.

Parkinson's disease (PD) is typically well recognized by its characteristic motor symptoms (e.g., bradykinesia, rigidity, and tremor). The cognitive symptoms of PD are increasingly being acknowledged by clinicians and researchers alike. However, PD also involves a host of emotional and communicative changes which can cause major disruptions to social functioning. These incude problems producing emotional facial expressions (i.e., facial masking) and emotional speech (i.e., dysarthria), as well as difficulties recognizing the verbal and nonverbal emotional cues of others. These social symptoms of PD can result in severe negative social consequences, including stigma, dehumanization, and loneliness, which might affect quality of life to an even greater extent than more well-recognized motor or cognitive symptoms. It is, therefore, imperative that researchers and clinicans become aware of these potential social symptoms and their negative effects, in order to properly investigate and manage the socioemotional aspects of PD. This narrative review provides an examination of the current research surrounding some of the most common social symptoms of PD and their related social consequences and argues that proactively and adequately addressing these issues might improve disease outcomes.

Methamphetamine acutely alters frontostriatal resting state functional connectivity in healthy young adults.

Chronic use of methamphetamine impairs frontostriatal structure and function, which may result in increased incentive-motivational responses to drug cues and decreased regulation of drug-seeking behavior. However, less is known regarding how the drug affects these circuits after acute administration. The current study examined the effects of a single dose of methamphetamine on resting state frontostriatal functional connectivity in healthy volunteers. Participants (n = 22, 12 female) completed two sessions in which they received methamphetamine (20 mg) and placebo before a resting state scan during functional magnetic resonance imaging. Participants also provided self-report measures of euphoria and stimulation at regular intervals. We conducted seed-based voxelwise functional connectivity analyses using three bilateral striatal seed regions: nucleus accumbens (NAcc), caudate, and putamen and compared connectivity following methamphetamine versus placebo administration. Additionally, we conducted correlational analyses to assess if drug-induced changes in functional connectivity were related to changes in subjective response. Methamphetamine increased NAcc functional connectivity with medial frontal regions (ie, orbitofrontal cortex, medial frontal gyrus, and superior frontal gyrus) and decreased NAcc functional connectivity with subgenual anterior cingulate cortex (ACC). Methamphetamine also increased functional connectivity between putamen and left inferior frontal gyrus (IFG), and individuals who displayed greater drug-induced increase in connectivity reported less euphoria and stimulation. These findings provide important information regarding the effects of methamphetamine on brain function in nonaddicted individuals. Further studies will reveal whether such effects contribute to the abuse potential of the drug and whether they are related to the frontostriatal impairments observed after chronic methamphetamine use.

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.

Gender differences in the behavioral and subjective effects of methamphetamine in healthy humans.

RATIONALE: Methamphetamine (MA) use is steadily increasing and thus constitutes a major public health concern. Women seem to be particularly vulnerable to developing MA use disorder, as they initiate use at a younger age and transition more quickly to problematic use. Initial drug responses may predict subsequent use, but little information exists on potential gender differences in the acute effects of MA prior to dependence. OBJECTIVE: We examined gender differences in the acute effects of MA on subjective mood and reward-related behavior in healthy, non-dependent humans. METHODS: Men (n = 44) and women (n = 29) completed 4 sessions in which they received placebo or MA under double-blind conditions twice each. During peak drug effect, participants completed the monetary incentive delay task to assess reaction times to cues signaling potential monetary losses or gains, in an effort to determine if MA would potentiate reward-motivated behavior. Cardiovascular and subjective drug effects were assessed throughout sessions. RESULTS: Overall, participants responded more quickly to cues predicting incentivized trials, particularly large-magnitude incentives, than to cues predicting no incentive. MA produced faster reaction times in women, but not in men. MA produced typical stimulant-like subjective and cardiovascular effects in all participants, but subjective ratings of vigor and (reduced) sedation were greater in women than in men. CONCLUSIONS: Women appear to be more sensitive to the psychomotor-related behavioral and subjective effects of MA. These findings provide initial insight into gender differences in acute effects of MA that may contribute to gender differences in problematic MA use.

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.

Effects of methamphetamine on neural responses to visual stimuli.

RATIONALE: The behavioral and reward-related effects of stimulant drugs have been studied extensively; yet the effect of stimulants on sensory processing is still relatively unknown. Prior brain imaging studies have shown that single doses of stimulant drugs increase neural function during cognitive and attentional processes. However, it is not clear if stimulant drugs such as methamphetamine (MA) affect neural responses to novel sensory stimuli, and whether these effects depend on the visual features of the stimuli. OBJECTIVE: In this study, we examined the effects of a single dose of MA (20 mg oral) on neural activation in response to visual stimuli that varied on "non-straight edges" (NSE), a low-level visual feature that quantifies curved/fragmented edges and is related to perceived image complexity. METHODS: Healthy adult participants (n = 18) completed two sessions in which they received MA and placebo in counterbalanced order before an fMRI scan where they viewed both high and low NSE images. Participants also completed measures of subjective drug effects throughout both sessions. RESULTS: During both sessions, high NSE images activated primary visual cortex to a greater extent than low NSE images. Further, MA increased activation only for low NSE images in three areas of visual association cortex: left fusiform, right cingulate/precuneus, and posterior right middle temporal gyrus. This interaction was unrelated to subjective drug effects. CONCLUSIONS: These findings suggest that stimulant drugs may change the relative sensitivity of higher order sensory processing to increase visual attention when viewing less complex stimuli. Moreover, MA-induced alterations in this type of sensory processing appear to be independent of the drugs' ability to increase feelings of well-being.

Oxytocin Reduces Cigarette Consumption in Daily Smokers.

INTRODUCTION: Despite widespread knowledge of the dangers of cigarette consumption, smoking continues to be a public health concern. One compound that has shown potential for treatment in preclinical models is the neuropeptide oxytocin (OT). The purpose of the present study was to examine the effects of intranasal oxytocin on cigarette craving, behavioral economic demand for cigarettes, and cigarette consumption, in regular smokers after 18 hours of abstinence. METHOD: Otherwise healthy daily smokers (n = 35) completed two sessions where they received OT (40 IU intranasal) or placebo (PBO) and completed measures of craving and cigarette demand, and they were given six opportunities to smoke partial cigarettes in exchange for money. RESULTS: On average participants smoked few cigarettes after receiving OT than after receiving PBO, and they reported less desire for additional cigarettes during the smoking period. OT did not affect cigarette demand or standardized measures of cigarette craving. CONCLUSIONS: This study suggests that OT decreases some indices of smoking desire and consumption, providing modest support for the idea that OT might be effective for reducing cigarette smoking. IMPLICATIONS: This study provides new evidence that oxytocin might have clinical value in the treatment of addictive disorders, in this case tobacco addiction. The study adds to a growing literature suggesting that this neuropeptide, which is mainly known for its role in social bonding and attachment, may also affect mood and motivational states relevant to addiction.

Neural responses to cues paired with methamphetamine in healthy volunteers.

Drug cues, or conditioned responses to stimuli paired with drugs, are widely believed to promote drug use. The acquisition of these conditioned responses has been well characterized in laboratory animals: neutral stimuli paired with drugs elicit conditioned responses resembling the motivational and incentive properties of the drug itself. However, few studies have examined acquisition of conditioning, or the nature of the conditioned response, in humans. In this study, we used fMRI to examine neural responses to stimuli that had been paired with methamphetamine or placebo in healthy young adults. Participants first underwent four conditioning sessions in which visual-auditory stimuli were paired with either methamphetamine (20 mg, oral) or placebo. Then on a drug-free test day, the stimuli were presented during an fMRI scan to assess neural responses to the stimuli. We hypothesized that the stimuli would elicit drug-like brain activity, especially in regions related to reward. Instead, we found that the methamphetamine-paired stimuli, compared to placebo-paired stimuli, produced greater activation in regions related to visual and auditory processing, consistent with the drug's unconditioned effects on sensory processing. This is the first study to demonstrate conditioned neural responses to drug-paired stimuli after just two pairings of methamphetamine in healthy adults. The study also illustrates that conditioned responses may develop to unexpected components of the drug's effects.

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.

The influence of social stress on time perception and psychophysiological reactivity.

Time perception is a fundamental component of everyday life. Although time can be measured using standard units, the relationship between an individual's experience of perceived time and a standard unit is highly sensitive to context. Stressful and threatening stimuli have been previously shown to produce time distortion effects, such that individuals perceive the stimuli as lasting for different amounts of time as compared to a standard unit. As a highly social species, humans are acutely sensitive to social stressors; however, time distortion effects have not been studied in the context of social stress. We collected psychophysiological (electrocardiogram and impedance cardiography) and time perception data before, during, and after a modified version of the Trier Social Stress Test for 42 participants. Based on prior theories and evidence from the time perception literature, we hypothesized that experiencing a stressful event would result in time distortion. This hypothesis was supported by the data, with individuals on average reproducing short and long duration negative and positive stimuli as lasting longer after experiencing social stress, t(41) = -3.55, p = .001, and t(41) = -4.12, p < .001 for negative stimuli, and t(41) = -2.43, p = .02, and t(41) = -3.07, p = .004 for positive stimuli. However, changes in time perception were largely unrelated to psychophysiological reactivity to social stress. These findings are in line with some other studies of time distortion, and provide evidence for the interoceptive salience model of time perception. Implications for mechanisms of time distortion are discussed.