Leukocyte responsiveness, a quantitative assay for subjective mental workload

Abstract

Assessing psychological stress and mental workload within work-based scenarios relies heavily upon qualitative, subjective, self-assessment techniques, many of which were originally intended for identifying specific pathological disorders and have reduced sensitivity when evaluating everyday stressors. Quantitative measures involve monitoring changes in the cardiopulmonary system and stress hormone concentration. Although these (e.g. heart rate and blood pressure) provide a basic, reactive indication of the presence of a psychological stressor, many are subject to influence by other bio-mechanisms, or are unable to provide rapid results due to complex laboratory analysis. This study demonstrates how immune responsiveness, known to be influenced by psychological stress, can be used to assess changes in mental workload. Healthy male and female subjects (aged between 26 and 55 years) provided capillary blood samples before and after completing the same, basic, driver-related tasks followed by a simple manoeuvre in two unfamiliar motor vehicles. Using a chemiluminescent technique termed Leukocyte Coping Capacity (LCC), the ability of leukocytes to produce reactive oxygen species in vitro was assessed. Significant post-stressor changes in leukocyte activity were demonstrated between treatment groups. These findings add weight to the proposition that leukocyte activation is a useful quantitative measure of psychological stress and mental loading in humans. This study demonstrates the diagnostic ability of LCC for use during ergonomic evaluation, however the potential industrial applications for this technique are numerous and diverse. KEY WORDSChemiluminescence; Ergonomics; Leukocytes; Mental Workload; Psychological Stress; Reactive Oxygen Species. 3 ABBREVIATIONSHmax-RLU adj , maximum control adjusted leukocyte activity; LCC, leukocyte coping capacity; RLU adj , control adjusted relative light units; T-max, time taken (minutes) to reach maximum control adjusted leukocyte activity; T=5, 10, and 15minutes, control adjusted leukocyte activity at 5, 10, and 15 minutes, respectively, into the 45 minute chemiluminescence sampling protocol. INTRODUCTIONEvaluation of psychological stress -a threat which would not require a physiological response which elicits physiological consequences (Segerstrom and Miller, 2004) relies heavily upon qualitative psychometric measures. Examples include: Present State Examination (Baker et al., 2003), the Brief Symptom Inventory (Brosig et al., 2007;Cuculi et al., 2006;Fellinger et al., 2007;Mansbach et al., 2005), and the BussDurkee Hostility Inventory (Bag et al., 2005). All were primarily designed to identify specific pathologic disorders, and validated using dysfunctional clinical populations with abnormal statistical distributions. Consequently these proved to have limited sensitivity when used to test below intended critical diagnostic thresholds (Lemyre and Tessier, 1988) -such as when investigating psychological and physiological transient laboratory stressors.As psychological...

LEUKOCYTE COPING CAPACITY AS A TOOL TO ASSESS CAPTURE- AND HANDLING-INDUCED STRESS IN SCANDINAVIAN BROWN BEARS (URSUS ARCTOS)

“…To measure the chemiluminescence produced in response to challenge, we prepared another tube as above but added 10 mL of phorbol 12-myristate 13acetate (PMA; Sigma P8139, Sigma-Aldrich, Oslo, Norway) at a concentration of 10 −5 mol L −1 . The PMA solution had been prepared in advance by diluting 5 mg of PMA in 500 ml of dimethyl sulfoxide (Sigma D 5879, Sigma-Aldrich, Oslo, Norway), which was then diluted to a concentration of 10 −5 mol L −1 in PBS buffer (Shelton-Rayner et al 2012). Individual aliquots were kept in the dark at −20 C until required.…”

Current understanding in climbing psychophysiology research

“…In particular, assessing the sensitivity of the hormone cortisol and its ability to quantify stress responses in climbing; along with considering more sensitive alternatives, such as Leukocyte Coping Capacity (Shelton-Rayner, Mian, Chandler, Robertson, & Macdonald, 2012). Similarly, the investigation of potential alternative anxiety inventories to the CSAI-2R may help to clarify responses; alternatives may include the recently developed Three-Factor Anxiety Inventory (Cheng, Hardy, & Markland, 2011).…”

“The stressed bird in the hand”: Influence of sampling design on the physiological stress response in a free-living songbird

“…Interestingly, LCC levels did not vary significantly between sampling regimes and decreased in all groups equally in the course of the experiment. LCC has been suggested as a reliable and sensitive tool to measure stress in mammals and birds and has been successfully applied to assess psychological stress in humans (Mian and MacDonald, 2010; Shelton-Rayner et al, 2012). In respect to the existing literature, a decrease in the LCC response, or a lack of recovery respectively, is an indicator for high stress levels and a reduced capacity to cope with and/or recover from a stress event (Huber et al, 2019; McLaren et al, 2003).…”

“…In one tube, 10 µl of PBS (pH 7.4) was added in order to measure unstimulated blood chemiluminescence levels, providing information on individual baseline levels of superoxide anion and acts as a control. In the second tube, we added 10 µl of 10 −5 mol l −1 phorbol-myristate-acetate (PMA; Sigma Aldrich, Vienna, Austria) to assess full blood chemiluminescence in response to this secondary (the first natural challenge occurs in vivo) chemical challenge (Shelton-Rayner et al, 2012). Blood chemiluminescence for each tube was measured for 30 seconds every 10 minutes over 80 minutes by using a portable high sensitivity chemiluminometer (Junior LB 9509, EG & G Berthold, Germany) and is expressed in relative light units (RLU; arbitrary scale reflecting photon count divided by 10).…”