Relationship of serum serotonin and salivary cortisol with sensation seeking

Analytic Background in the Neuroscience of the Potential Project "Hippocrates"

This paper reviews the principles identified in analytic neuroscience that could be used in the setup of an international project, "Hippocrates" (H-project), named after the author of the endocrine theory of temperaments. The H-project can aim to summarize the findings in functional neurochemistry of consistent behavioural patterns (CBPs) in health (such as temperament traits) and psychopathology (symptoms of psychiatric disorders); to have systematically structured neurochemical investigations; to have an analysis of CBPs that include all ranges of behavioural histories and to have these modules complemented by regional contrasts related to climate, diets and other bio-environmental factors. The review highlights the benefits of constructivism and illustrates the contrast between constructivism and current approaches in terms of analytic and methodological aspects. (1) "Where" the neurochemical biomarkers should be measured: the review expands the range of needed measurements to out-of-brain systems, including environmental factors, and explores the concept of Specialized Extended Phenotype. (2) "What" should be measured but is missing: the review points to the need for measurement of the "Throw & Catch" neurochemical relays; behavioural and neuronal events contributing to the consistency of the CBPs but not documented in measurements. (3) Structuring the H-project's setup: the paper briefly describes a proposed earlier neurochemical framework, Functional Ensemble of Temperament that that accommodates the neurochemical continuum between temperament and symptoms of psychiatric disorders. This framework is in line with documented "Throw & Catch" neurochemical relays and can also be used to organize data about the personal and professional history of an individual.

Dietary supplementation of acetate-conjugated tryptophan alters feed intake, milk yield and composition, blood profile, physiological variables, and heat shock protein gene expression in heat-stressed dairy cows

The purpose of this study was to investigate the effects of dietary supplementation of rumen-protected tryptophan (RPT) at four levels on milk yield, milk composition, blood profile, physiological variables, and heat shock protein gene expression in dairy cows under conditions of moderate-severe heat stress (MSHS, THI = 80~89). Sixteen early-lactating dairy cows (body weight = 719 ± 66.4 kg, days in milk = 74.3 ± 7.1, milk yield = 33.55 ± 3.74 kg, means ± SEM) were randomly assigned in a factorial arrangement to one of the four treatments: control group (n = 4, no RPT supplementation), 15 g/d RPT (n = 4), 30 g/d RPT (n = 4), or 60 g/d RPT group per cow (n = 4) supplemented to the TMR. A higher dry matter intake (DMI) and milk yield were found in the 30 g RPT group compared with the other groups, and the 3.5% fat-corrected milk yield, energy-corrected milk yield, milk fat, protein, β-casein, mono-unsaturated fatty acid, and poly-unsaturated fatty acid contents, and serum glucose content were observed in the 30 g RPT group (p < 0.05). The milk lactose concentration was significantly higher in the 30 g RPT group compared with the control and 60 g RPT groups (p < 0.05). The plasma cortisol level was lower, while the serotonin and melatonin concentrations were higher in the 30 g group compared with the other groups (p < 0.05). Heat shock protein (HSP) 70 expression was downregulated in the control and 15 g RPT groups, whereas the expression of HSP90 and HSPB1 remained unchanged among the groups. In particular, the 30 g RPT group was considered to have an improved DMI, milk yield, and lactose concentration, as well as anti-heat stress effects due to the simulation of serotonin and melatonin during MSHS.

Mindful Sensation Seeking: An Examination of the Protective Influence of Selected Personality Traits on Risk Sport-Specific Stress

Stress often has a negative influence on sports performance. Stress-induced decreases in performance can be especially disastrous for risk sports athletes, who often put their life at risk when practicing their sport. Therefore, it is of great importance to identify protective factors in stressful situations in risk sports. On average, risk sports athletes score extremely high on the personality trait sensation seeking. At the same time, theoretical considerations about dispositional mindfulness suggest that mindful athletes can handle stress more effectively. The main goal of this experiment is to examine the influence of sensation seeking and mindfulness on the stress response to a risk sport-specific stressor. To induce stress, 88 male students completed the Heidelberg Risk Sport-Specific Stress Test (HRSST) which utilizes fear of falling as the stressful event during a climbing exercise. Psychological (anxiety) and physiological (cortisol) responses were measured at multiple time points before and after the HRSST to determine the severity of the stress response. In reaction to the stressor, a significant increase in self-reported state anxiety, but no significant increase in cortisol were observed. The mindfulness subscale external observation correlated positively with anxiety in the climbing wall, sensation seeking and the anxiety scales after the jump correlated negatively and sensation seeking predicted anxiety subscales after the jump in hierarchical regression analyses. However, mindfulness did not predict anxiety measures. Neither sensation seeking nor mindfulness correlated significantly with cortisol levels. The results suggest that high sensation seekers perceive a risk sport-specific stressor as less stressful. The missing physiological response might be explained by the Cross-Stressor-Adaptation-Hypothesis and particularities of the sample. Good internal observers might be especially aware of their need of stimulation and new experiences, which in turn might explain the higher experience-seeking scores. Future studies should further examine the role of mindfulness in stressful situations and the interaction of its subscales with sensation seeking. The current experiment offers new possibilities for adjoining research fields at the interface between sports sciences, psychology and medicine: The findings can be transferred to high risk professions such as police officers, firefighters and military forces (e.g., for selection processes or for interventions).

Effects of Coping-Related Traits and Psychophysiological Stress Responses on Police Recruits' Shooting Behavior in Reality-Based Scenarios

Police officers are often required to perform under high-stress circumstances, in which optimal task performance is crucial for their and the bystanders' physical integrity. However, stress responses, particularly anxiety and increased cortisol levels, shift attention from goal-directed to stimulus-driven control, leaving police officers with poor shooting performance under stress. Cardiac vagal activity and coping-related traits (i.e., self-control, sensation seeking) might help individuals to maintain performance under stress. So far, only few studies have integrated coping-related traits, psychophysiological stress markers and occupationally meaningful measures of behavior to investigate police officers' work performance under stress. Therefore, the present study investigated 19 police recruits (M _age = 22.84, SD = 3.30) undergoing a reality-based shooting scenario in two experimental conditions in a within-design: low stress (LS) against a non-threatening mannequin, and high stress (HS), involving physical threat by an opponent. Psychological (i.e., anxiety, mental effort) and physiological stress responses (i.e., salivary cortisol, alpha-amylase, cardiac vagal activity) as well as shooting accuracy were repeatedly assessed. It was hypothesized that under stress, police recruits would demonstrate elevated psychophysiological stress responses and impaired shooting performance. Elevated psychophysiological stress responses would negatively influence shooting performance, whereas self-control, sensation seeking and cardiac vagal activity would positively influence shooting performance. While recruits reported significantly higher anxiety and mental effort in the HS scenario, both scenarios elicited comparable physiological responses. Overall, shooting accuracy was low and did not significantly decrease in the HS scenario. Shooting performance was predicted by self-control in the LS scenario and by post-task cardiac vagal activity in the HS scenario. While increased anxiety hints at a successful stress manipulation, physiological responses suggest similar stress levels for both scenarios, diminishing potential behavioral differences between the scenarios. Performance efficiency decreased under stress, as indicated by increasing mental effort. Findings on self-control suggest that suppressing negative stress responses might lead to impaired goal-directed attention, resulting in performance decrements. For police research and training, high-realism scenarios afford an opportunity to investigate and experience psychophysiological stress responses.

Cortisol and behavioral reaction of low and high sensation seekers differ in responding to a sport-specific stressor

BACKGROUND/OBJECTIVES

Sensation seeking is closely related to practicing high-risk sports. This domain offers individuals an opportunity to achieve an increased level of arousal. Moreover, stress reactivity implies interindividual differences in the capacity to respond to a stressor. The purpose of this study was to examine whether high sensation seekers (HSS) compared to low sensation seekers (LSS) experience lower levels of stress on a physiological and psychological basis. Stress was induced in a sport-specific experimental paradigm with a climbing task through a jump into the rope.

METHODS

Two extreme groups (n = 28 male athletes) were examined in a mixed-factorial design (between: HSS vs. LSS; within: repeated measurements of several variables related to stress reactivity - cortisol, heart rate, anxiety).

RESULTS

In response to the stressor HSS compared to LSS released a significantly lower amount of cortisol and needed less time for the climbing task. Heart rate and anxiety were not significant.

CONCLUSIONS

Individuals seem to react physiologically differently to a sport-specific stressor, depending on their level of sensation seeking. HSS seem to be less strained, and seem to perform better. These findings might be relevant not only for the evaluation of (sport-) psychological interventions but also for other contexts (e.g., special forces).

The additive effects of depressive symptoms and polysubstance use on HIV risk among gay, bisexual, and other men who have sex with men

INTRODUCTION

Among gay, bisexual, and other men who have sex with men (GBM), collinearity between polysubstance use and mental health concerns has obscured their combined effects on HIV risk with multivariable results often highlighting only one or the other.

METHODS

We used mediation and moderation analyses to examine the effects of polysubstance use and depressive symptoms on high-risk sex (i.e., condomless anal sex with serodiscordant/unknown status partner) in a sample of sexually-active GBM, aged ≥16 years, recruited in Metro Vancouver using respondent driven sampling. Hospital Anxiety and Depression Scale scores assessed mental health. Alcohol Use Disorder Identification Test scores assessed alcohol disorders. Poly-use of multiple drug types (e.g., stimulants, sedatives, opiates, hallucinogens) was assessed over the previous six months.

RESULTS

Among 719 predominantly white (68.0%), gay-identified (80.7%) GBM, alcohol use was not associated with increased prevalence of high-risk sex. Controlling for demographic factors and partner number, an interaction between polysubstance use and depressive symptoms revealed that the combined effects were additively associated with increased odds for high-risk sex. Mediation models showed that polysubstance use partially mediated the relationship between depressive symptoms and high-risk sex.

CONCLUSION

An interaction effect between polysubstance use (defined by using 3 or more substances in the past six months) and depressive symptoms (defined by HADS scores) revealed that the combination of these factors was associated with increased risk for high-risk sex - supporting a syndemic understanding of the production of HIV risk.

Could Watching TV Be Good for You? Examining How Media Consumption Patterns Relate to Salivary Cortisol

This research explores whether media diet influences health, not through its effects on cognition and behavior but rather through its effects on biomarkers of stress, which are implicated in a host of acute and chronic illnesses. Two hundred and forty young adults completed assessments of their media consumption habits followed at least 2 days later by measures of the stress-related hormone cortisol. Results suggest that frequency of consuming different media and genres may decrease cortisol under certain conditions and increase them under others. Further, the patterns of results were wholly different from those found for perceived stress. The implications of these findings for health-related media effects and theoretical development are discussed.

A Biomarker of Risk-Prone Behavioral Phenotype Correlates With Winning in a Game of Skill

Abstract. The predisposition to take risk is a personality trait associated with dangerous or maladaptive behavior. Related to this, biomarkers associated with risk proneness such as low platelet monoamine oxidase (MAO) activity level are typically considered as prognostic for higher likelihood of undesirable behavior in real-life settings. In this study we explored whether this biomarker is also indicative of risk proneness in a game situation where serious real-life adaptations and motivations are absent or minimized and risk is more or less symbolic. We adapted a game of skill where in order to get a high score “risky” actions had to be taken by the players. Scores obtained in the game correlated with the (relatively low) platelet MAO activity. Our results show that (1) the same markers that are informative for real-life behavior and adaptations involving risk and/or sensorimotor skills based performance may be informative also in a game setting, (2) in specific circumstances biomarkers associated with predisposition to risk may be associated with success, and (3) the novel game of skill tested in this context has a potential to be developed to a model of risk-involving behavior allowing quantifiable dependent measures of performance and purposeful manipulation of variables without real adverse effects on health or social relations.

Temperament and arousal systems: A new synthesis of differential psychology and functional neurochemistry

This paper critically reviews the unidimensional construct of General Arousal as utilised by models of temperament in differential psychology for example, to underlie 'Extraversion'. Evidence suggests that specialization within monoamine neurotransmitter systems contrasts with the attribution of a "general arousal" of the Ascending Reticular Activating System. Experimental findings show specialized roles of noradrenaline, dopamine, and serotonin systems in hypothetically mediating three complementary forms of arousal that are similar to three functional blocks described in classical models of behaviour within kinesiology, clinical neuropsychology, psychophysiology and temperament research. In spite of functional diversity of monoamine receptors, we suggest that their functionality can be classified using three universal aspects of actions related to expansion, to selection-integration and to maintenance of chosen behavioural alternatives. Monoamine systems also differentially regulate analytic vs. routine aspects of activities at cortical and striatal neural levels. A convergence between main temperament models in terms of traits related to described functional aspects of behavioural arousal also supports the idea of differentiation between these aspects analysed here in a functional perspective.

Effects of Low Frequency Prefrontal Repetitive Transcranial Magnetic Stimulation on the N2 Amplitude in a GoNogo Task

During the last decade, repetitive transcranial magnetic stimulation (rTMS) of the prefrontal cortex has become established as a treatment for various mental diseases. The rational of prefrontal stimulation has been adapted from the mode of action known from rTMS using motor-evoked potentials though little is known about the precise effect of rTMS at prefrontal sites. The objective of the current study is to investigate the inhibitory effect of prefrontal 1 Hz rTMS by stimulating the generators of event-related potentials (ERP) which are located in the prefrontal cortex. Thus, 1 Hz rTMS was applied offline over the left dorsolateral prefrontal cortex (DLPFC) and the medial prefrontal cortex (MPFC) in 18 healthy subjects who subsequently underwent a GoNogo task. Both active conditions were compared to sham rTMS within a randomized and counterbalanced cross-over design in one day. ERPs were recorded during task performance and the N2 and the P3 were analysed. After 1 Hz rTMS of the left DLPFC (but not of the MPFC), an inhibitory effect on the N2 amplitude was observed, which was related to inhibitory control. In contrast, after 1 Hz rTMS of the MPFC (but not at the left DLPFC) a trend towards an increased P3 amplitude was found. There was no significant modulation of latencies and behavioural data. The results argue in favour of an inhibitory effect of 1 Hz rTMS on N2 amplitudes in a GoNogo task. Our findings suggest that rTMS may mildly modulate prefrontally generated ERP immediately after stimulation, even where behavioural effects are not measurable. Thus, combined rTMS-ERP approaches need to be further established in order to serve as paradigms in experimental neuroscience and clinical research.

Sensation seeking in major depressive patients: relationship to sub-threshold bipolarity and cyclothymic temperament

BACKGROUND

High levels of sensation seeking (SS) have been traditionally reported for lifetime bipolar disorder (BD) and/or substance use disorder (SUD) rather than major depressive disorder (MDD). Nonetheless, a renewed clinical attention toward the burden of sub-threshold bipolarity in MDD, solicits for a better assessment of "unipolar" major depressive episodes (MDEs) via characterization of putative differential psychopathological patterns, including SS and predominant affective temperament.

METHODS

Two hundred and eighty currently depressed cases of MDD and 87 healthy controls were screened using the Zuckerman's sensation seeking scale-Form-V, the Hypomania Check List-32-item (HCL-32), the Temperament Evaluation of Memphis, Pisa, Paris and San Diego Auto-questionnaire-110-item, the Barratt Impulsivity Scale-11-item, the State-Trait Anxiety Inventory modules and the Structured Clinical Interview for DSM-IV axis-I disorders. Cases were divided into HCL-32(+)(sub-threshold bipolar)/HCL-32(-)("true" unipolar depressed) depending on the HCL-32 total score.

RESULTS

Upon correlation and multivariate regression analyses, the HCL-32(+) patients showed the highest levels of SS, higher prevalence of cyclothymic temperament, and higher rates of multiple lifetime axis-I co-morbidities, including SUD.

LIMITS

Recall bias on some diagnoses, including BD, grossly matched healthy control group, lack of ad-hoc validated measures for ADHD, SUD, or axis-II disorders.

CONCLUSIONS

In our sample, the occurrence of higher levels of SS in "sub-threshold" bipolar cases outlined a differential psychopathological profile compared to DSM-defined "true unipolar" cases of MDE. If confirmed by replication studies, these findings may aid clinicians in delivering a more accurate diagnosis and a safer use of antidepressants in some MDD cases.