Revealing the Acute Effects of Dietary Components on Mood and Cognition: The Role of Autonomic Nervous System Responses.

A growing body of literature suggests dietary components can support mood and cognitive function through the impact of their bioactive or sensorial properties on neural pathways. Of interest, objective measures of the autonomic nervous system-such as those regulating bodily functions related to heartbeat and sweating-can be used to assess the acute effects of dietary components on mood and cognitive function. Technological advancements in the development of portable and wearable devices have made it possible to collect autonomic responses in real-world settings, creating an opportunity to study how the intake of dietary components impacts mood and cognitive function at an individual level, day-to-day. In this paper, we aimed to review the use of autonomic nervous system responses such as heart rate or skin galvanic response to investigate the acute effects of dietary components on mood and cognitive performance in healthy adult populations. In addition to examining the existing methodologies, we also propose new state-of-the-art techniques that use autonomic nervous system responses to detect changes in proxy patterns for the automatic detection of stress, alertness, and cognitive performance. These methodologies have potential applications for home-based nutrition interventions and personalized nutrition, enabling individuals to recognize the specific dietary components that impact their mental and cognitive health and tailor their nutrition accordingly.

The Matrix Matters: Beverage Carbonation Impacts the Timing of Caffeine Effects on Sustained Attention.

Both caffeine and the perception of refreshment delivered by cooling, tingling, and mouth-watering flavors have individually been shown to positively impact cognitive performance and mood, though presently there is limited evidence on their possible combined effects. This study explored the contribution of refreshing compounds in beverages, namely, carbon dioxide and citric acid, on the acute effects of caffeine on sustained attention and self-rated physical and mental energy. A randomized, controlled crossover trial was conducted by testing three products: a carbonated caffeinated beverage; a comparator caffeinated beverage; and a flavor-matched control beverage. Findings from 24 healthy adults revealed product-dependent variations in cognitive performance during a 60-min visual sustained-attention task, suggesting that the carbonated-caffeinated beverage led to faster, greater and more consistent levels of accuracy, compared to the control beverage. Specifically, significant differences were found between: (1) the carbonated-caffeinated beverage and the caffeinated beverage, and (2) between the caffeinated beverage and the control beverage for number of hits, reaction time and false alarm scores. Both caffeinated beverages led to higher physical and mental energy, and lower physical and mental fatigue 60-min post-consumption. These findings suggest beneficial effects on sustained attention through the combination of caffeine with refreshing compounds.

Personal Resources and Organizational Outcomes: Sex as a Moderator of the Complex Relationships Between Self-Esteem, Heart Rate Variability, and Work-Related Exhaustion.

Global self-esteem represents a protective personal resource lowering the risk of psychological distress. Research conducted in the work setting has confirmed the psychosocial benefits of high self-esteem. However, research linking self-esteem to neurobiological adaptability appears quite scarce. In this study, we propose a theoretical model in which self-esteem predicts work-related exhaustion indirectly, through the mediation of heart rate variability (HRV) and negative affect at work. Moreover, we explore the relationship between self-esteem and HRV. From one side, one would expect a positive link between self-esteem and HRV, signaling higher autonomic adaptability. However, recent studies have shown that in women, such associations become more complex, with even reversed patterns as compared with that in men. Thus, we included sex as a moderator of the relationship between HRV and self-esteem. The model was tested on a sample of 110 individuals working in the relational professions (54% males; M age = 42.6, SD = 13.73), observed for an entire workday. Results confirmed the protective role of self-esteem against the experience of negative affect and (indirectly) work-related exhaustion. Symptoms of exhaustion at work were also negatively predicted by HRV, and both HRV and negative affect acted as mediators of the relationship between self-esteem and work-related exhaustion. Notably, sex differences emerged in the association between global self-esteem and cardiac vagal tone at work: in women, self-esteem was negatively related to HRV, which in turn led to higher work-related exhaustion, whereas in men, no evidence of this indirect effect appeared. Burnout prevention programs should not ignore important sex differences in how individuals respond to work-related stress.

Associations between inertia of negative emotions and diurnal cortisol in a sample of college students.

Emotional inertia refers to the extent to which emotional states are predictable over time and are resistant to change. High emotional inertia, characterized by emotional states that carry over from one moment to the next, has been linked with both psychological maladjustment and impaired emotion regulation abilities. However, little research has examined the psychobiological correlates of emotional inertia. As such, in this study, we examined the association between inertia of negative emotions with cortisol, the end product of the hypothalamic pituitary adrenal (HPA) axis, one of the body's primary stress response systems. Participants were 76 college students (24% male, Mage=18.53, SD=0.37), who completed five corresponding daily diaries and salivary samples to ascertain cortisol per day for 3 consecutive days. Hierarchical linear models indicated that greater inertia of negative emotion across the three days was associated with smaller cortisol awakening responses (CAR) and lower AUCg, even when controlling for average negative emotion and momentary stress perception. There were no associations with the diurnal cortisol slope. These findings shed light on the neurobiological mechanisms involved in emotion dynamics.

Inertia of emotions and inertia of the heart: Physiological processes underlying inertia of negative emotions at work.

Emotional inertia is a key feature of emotional dynamics and it refers to the degree to which a current emotional state can be predicted by a previous emotional state. In this study, using the experience sampling method, we examined the relationship between inertia of negative emotions at work and parasympathetic activity, measured by vagally-mediated heart rate variability (HRV). In line with current literature on HRV, we propose that temporal dependency of negative emotions at work may be associated to lower HRV, an important marker of the ability to flexibly adjust to a changing environment. Participants (n = 120) were prompted six times during a regular workday, while wearing a heart rate monitor. In accordance with the polyvagal theory and the model of neurovisceral integration, findings supported our hypothesis and indicated that workers with lower HRV tend to show high time persistence of negative emotions at work. Practical implications and directions for future research are discussed.

Second-Order Growth Mixture Modeling in Organizational Psychology: An Application in the Study of Job Performance Using the Cusp Catastrophe Model.

In recent years, research in organizational psychology has witnessed a shift in attention from a mostly variable-focused approach, to a mostly person-focused approach. Indeed, it has been widely recognized that the study of worker's heterogeneity is a meaningful and necessary task of researchers dealing with human behavior in organizational contexts. As a consequence, there has been growing interest in the application of statistical analyses able to uncover latent sub-groups of workers. The present contribution was conceived as a tutorial for the application of one of these statistical analyses, namely second-order growth mixture modeling, and to illustrate its inner links with concepts from non-linear dynamic models. Throughout the paper, we provided (a) a discussion on the relationships between growth mixture modeling and the cusp catastrophe model; (b) Mplus syntaxes and output excerpts of a longitudinal analysis conducted on job performance (N = 420 employees rated once a year for four consecutive years);

The costly burden of an inauthentic self: insecure self-esteem predisposes to emotional exhaustion by increasing reactivity to negative events.

BACKGROUND AND OBJECTIVES: A long research tradition has investigated the impact of stress on university students by assuming that individuals have a limited reservoir of resources, and that negative events and circumstances progressively drain resources thereby producing exhaustion. A recent research tradition, instead, has focused on the detrimental consequences of discrepant levels of implicit (ISE) and explicit (ESE) self-esteem on the development of stress-related symptoms. The present research attempted to merge the aforementioned approaches, with the aim of explaining significant predictors of stress. DESIGN: Within the framework of a Longitudinal Structural Equation Model, we followed a moderated-mediated approach. METHOD: A sample of university students (N = 209; 66% females) completed a questionnaire battery including measures of ISE, ESE, perceptions of negative events, and emotional exhaustion. Participants were assessed once a week for eight consecutive weeks. RESULTS: ISE significantly moderated the relationship between ESE and negative events; in turn, the latter significantly predicted emotional exhaustion. Monte Carlo method for assessing mediation showed that negative events significantly mediated the relationship between incongruent self-esteem and emotional exhaustion. CONCLUSIONS: The detrimental role of incongruent self-esteem has been corroborated. Practical implications and suggestions for future research dealing with stress in a university setting were provided.