Activation of the hypothalamic-pituitary adrenal axis in response to a verbal fluency task and associations with task performance

The role of sex hormones, oral contraceptive use, and its parameters on visuospatial abilities, verbal fluency, and verbal memory

Sex hormones can cross the blood-brain barrier and access brain regions underlying higher-order cognition. Containing synthetic sex hormones, oral contraceptives (OC) have been found to modulate visuospatial and verbal abilities, though inconsistencies have been found in the literature. Among possible explanations, certain OC use parameters (progestin androgenicity, synthetic hormone levels, duration of use) have not received consistent consideration. Thus, the objectives were to (1) examine group differences between men, combined OC users, and naturally cycling women (NC women; not using OC) in visuospatial abilities, verbal fluency, and verbal memory and (2) investigate the contribution of endogenous and exogenous sex hormones on these effects. We also aimed to (3) identify OC use parameters relevant to cognitive outcomes. In total, 70 combined OC users, 53 early follicular (EF) women, 43 pre-ovulatory (PO) women, and 47 men underwent cognitive tests. Performance was compared based on hormonal milieus (OC, EF, PO, men) and OC users' contraceptive androgenicity (anti, low, high). Correlations between performance, hormone levels and OC use duration were also conducted. OC use dampened the sex difference that typically favors men in 3D visuospatial abilities, whereas its duration of use positively predicted verbal fluency. Androgenicity and hormone levels did not predict performance in any task. These results highlight the importance of considering OC use duration. Results also did not support a role for androgenicity in cognition. Importantly, combined OC use (including prolonged use) does not impair visuospatial, verbal, and memory functions in a healthy young sample.

Biological stress responses to multitasking and work interruptions: A randomized controlled trial

In the course of digitalization, new stressors are emerging. In modern working and living environments, two ubiquitous, technology-mediated stressors are multitasking demands and work interruptions. However, biological stress response patterns to multitasking and work interruptions have been sparsely investigated so far. We thus aimed to comprehensively assess biological stress response patterns to both stressors and, additionally, test whether responses differ between digital and partially non-digital settings. A controlled experimental set-up was established and humans' biological markers of the Sympathetic Nervous System (SNS), the hypothalamic-pituitary adrenal (HPA) axis, and the immune system were assessed. N = 186 healthy participants (mean age: 23.2 ± 4.3 years, 74.7% female, body mass-index: 22.3 ± 3.1 kg/m2) took part in this pre-registered study. Each participant was randomly assigned to one of 6 experimental conditions (1 digital single-task, 3 dual-tasks [2 parallel tasks and 1 interruption], 1 multitasking, and 1 passive, control condition). Each one of the dual-tasking as well as the multitasking conditions included a non-digital sub-task, i.e., performing a task in presence of an examiner. All other conditions involved digital tasks only. Salivary alpha-amylase (sAA) levels as a marker for SNS reactivity significantly changed in work interruptions, parallel dual-tasking, and multitasking conditions. No changes were found for control conditions. Furthermore, no significant changes over time and no differences between the conditions were identified for three biological markers: cortisol as marker for HPA axis activity as well as for two immune system markers (secretory Immunoglobulin-A, C-reactive protein). A time course similar to sAA was found for perceived stress: with increases during task execution and decreases afterwards in multitasking and parallel dual-tasking. Yet, it did not change for the work interruption, passive control, and single-tasking condition. Overall, our findings show that dual- and multitasking are perceived as stressful and are associated with an activation of the SNS, but not with responses of HPA axis or immune system. This was consistent for digital as well as partially digital task demands. Our findings will also inform future research into the differential stress effects of digital and non-digital tasks to advance our understanding of biological stress response-patterns to multitasking and work interruptions. Therefore, our findings are highly relevant for understanding the long-term biological health effects of stress in modern (digitalized) environments.

Differences in stress system (re-)activity between single and dual- or multitasking in healthy adults: A systematic review and meta-analysis

AbstractIn the age of digitization, multitasking requirements are ubiquitous, especially in the workplace. Multitasking (MT) describes the activity of performing multiple (at least two) tasks at the same time. Dual tasking (DT) refers to the sequential switching between two tasks. The aim of our systematic review and meta-analysis was first to investigate whether physiological stress systems become activated in response to or during MT/DT and, secondly, whether this (re-)activity is higher compared to single tasking. We focused on the Sympathetic Nervous System (SNS), the Parasympathetic Nervous System (PNS), the hypothalamic-pituitary adrenal (HPA) axis, and the immune system. The systematic review has been pre-registered with PROSPERO (CRD42020181415). A total of twenty-five articles were identified as eligible, in which n = 26 studies were reported, with N = 1,142 participants. Our main findings are that SNS activity is significantly higher and PNS activity is significantly lower during MT/DT than during single tasking. Only two studies were found, in which HPA axis (re-)activity was surveyed. No eligible study was identified in which immune system (re-)activity was investigated. This is the first systematic synthesis of the literature base showing that stress system activity is increased during MT/DT in comparison to single-tasking.

Physiological stress in response to multitasking and work interruptions: Study protocol

BACKGROUND

The biopsychological response patterns to digital stress have been sparsely investigated so far. Important potential stressors in modern working environments due to increased digitalization are multitasking and work interruptions. In this study protocol, we present a protocol for a laboratory experiment, in which we will investigate the biopsychological stress response patterns to multitasking and work interruptions.

METHODS

In total, N = 192 healthy, adult participants will be assigned to six experimental conditions in a randomized order (one single-task, three dual-task (two in parallel and one as interruption), one multitasking, and one passive control condition). Salivary alpha-amylase as well as heart rate as markers for Sympathetic Nervous System Activity, heart rate variability as measure for Parasympathetic Nervous System (PNS) activity, and cortisol as measure for activity of the hypothalamic-pituitary adrenal (HPA) axis will be assessed at six time points throughout the experimental session. Furthermore, inflammatory markers (i.e., IL-6, C-reactive protein (CRP), and secretory immunoglobulin-A) will be assessed before and after the task as well as 24 hours after it (IL-6 and CRP only). Main outcomes will be the time course of these physiological stress markers. Reactivity of these measures will be compared between the experimental conditions (dual-tasking, work interruptions, and multitasking) with the control conditions (single-tasking and passive control).

DISCUSSION

With this study protocol, we present a comprehensive experiment, which will enable an extensive investigation of physiological stress-responses to multitasking and work interruptions. Our planned study will contribute to a better understanding of physiological response patterns to modern (digital) stressors. Potential risks and limitations are discussed. The findings will have important implications, especially in the context of digital health in modern working and living environments.

Physiological stress in safer cycling in older age (SiFAr-stress): effect of a multicomponent exercise intervention-a study protocol for a randomized controlled trial

BACKGROUND

SiFAr-Stress investigates the impact of cycling on stress levels in older adults. Uncertainty due to change to motorized bicycle or fear of falling can be perceived as stressors for cyclists. Stress activates different physiological signal cascades and stimulates the hypothalamic-pituitary-adrenal (HPA) axis, which leads to the release of the stress hormone cortisol and further effects such as the development of low-grade inflammation. Both can-in the long term-be associated with negative health outcomes. The aim of the study SiFAr-Stress is to analyze inflammatory processes as well as the activity of stress systems before and after a cycling intervention for older adults.

METHODS

In this study, community-dwelling older adults aged 65 years and older will be randomly assigned to either a cycling or a control intervention in a parallel-group design. Objective HPA axis-related measures (saliva cortisol and hair cortisol) will be assessed before, after, and 6-9 months after the cycling and control intervention (T0, T1, and T2). Furthermore, changes in cortisol reactivity in response to the cycling intervention will be investigated at the second and seventh training lessons. Furthermore, secondary outcomes (fear of falling, perceived stress, salivary alpha amylase, and C-reactive protein) will be assessed at T0, T1, and T2.

DISCUSSION

The study will be the first, in which stress- and health-related bio-physiological outcomes will be assessed in the context of a multicomponent exercise intervention, addressing cycling in older adults. It will enable us to better understand the underlying patho-physiological and psychological mechanisms and will help to improve interventions for this target group.

TRIAL REGISTRATION

ClinicalTrials.gov NCT04362514 . Prospectively registered on 27 April 2020.

Resistance training as an acute stressor in healthy young men: associations with heart rate variability, alpha-amylase, and cortisol levels

Regular resistance training has been shown to have many physiological and psychological health benefits. However, the underlying physiological processes are not yet fully understood. One explanation is that resistance training acts like an acute stressor and modulates physiological pathways that are associated with the stress response such as the sympathetic nervous system (SNS), the parasympathetic nervous system (PNS), and the hypothalamic-pituitary-adrenal (HPA) axis. This was systematically investigated in our study. Participants were 45 healthy men who had been doing resistance training regularly for at least nine months. Salivary α-amylase and heart rate that were used as markers for SNS activity increased during the training and decreased afterwards. PNS activity that was assessed by means of heart rate variability parameters decreased during the training and increased after it. Salivary cortisol that was used as marker for HPA axis activity decreased throughout the session. Furthermore, an improvement of positive affect was found after the training. However, additional analyses indicated that the physiological response patterns were found for participants who chose upper-body exercises (in contrast to lower-body exercises) only. Therefore, we were able to show that an upper-body resistance training acts partially like an acute stressor which leads to the typical SNS and PNS - but not HPA axis - stress responses. We conclude that resistance trainings might be an alternative to classical relaxation programs which would have the additional advantage that it is a physical training at the same time. However, more research is needed to develop specific trainings which entirely fulfill this goal.

Associations between Attention and Implicit Associative Learning in Healthy Adults: The Role of Cortisol and Salivary Alpha-Amylase Responses to an Acute Stressor

In this study, we investigated the associations between implicit associative learning with the cortisol and salivary alpha-amylase (sAA) stress response to an acute stressor as well as their associations with attention. Eighty one healthy adults (25 male) participated and either performed the socially evaluated cold-pressor test (SECPT) or a warm-water control task (WWT). Either prior to or immediately after the SECPT/WWT, participants implicitly learned digit-symbol pairs. A not-previously announced recall test was conducted about 20 min after the SECPT/WWT. Attention was assessed by means of a Stroop task at nine time points over the course of the experiment. Memory recall performance was not significantly associated with the acquisition time point (pre or post stressor) and did not significantly differ between the responder groups (i.e., non-responders, sAA-and-cortisol responders, only sAA responders, and only cortisol responders). Attentional performance increased throughout the experiment (i.e., reaction times in the Stroop task decreased). No differences in the attentional time course were found between the responder groups. However, some associations were found (p_uncorrected < 0.05) that did not pass the multiple comparison adjusted alpha level of α_adjusted = 0.002, indicating different associations between attention and implicit learning between the responder groups. We conclude that the associations of sAA and cortisol responses with implicit learning are complex and are related to each other. Further studies in which both (sAA and cortisol responses) are selectively (de-) activated are needed. Furthermore, different learning tasks and less—potentially stressful—attentional assessments should be used in future research. Moreover, field studies are needed in which the associations between acute stress and implicit associative learning are investigated in everyday life.