Salivary Cortisol Level, Salivary Flow Rate, and Masticatory Muscle Activity in Response to Acute Mental Stress: A Comparison between Aged and Young Women

Abstract

Background: Age-related effects on physiological stress reactions regarding changes in salivary cortisol concentration, saliva flow rate, and masticatory muscle activity, as well as the corresponding perceived mental stress and performance in response to acute stressors, have not yet been fully described. Objective: Thus, the aim of this study was to assess the age-related variations in these variables in response to minor acute and naturalistic stressors in terms of computer tasks. Methods: 13 aged (60–70 years old) and 13 young (20–30 years old) women with frequent practice and long experience with computer use were recruited by personal contact and flyers. The subjects were healthy and had full dental arches and no orofacial pain. The computer tasks were randomized and comprised a mentally demanding, modified Stroop colour-word test (CWT) and a less demanding reference test, both with a duration of 20 min and with equal physical demand. Visual analogue scales for global assessment of mental stress and perceived task difficulty and performance, measurements of saliva flow rate and cortisol concentration (unstimulated whole saliva), as well as surface electromyography of the temporalis and masseter muscles were used for assessment, and Spearman correlation analysis and Anova with repeated measures were used for statistical evaluation. Results: The perceived task-related stress and task difficulty were significantly higher and the personal satisfaction with the task performance significantly poorer in the aged women. The cortisol concentration, indicating the stress level, showed a small, but significant increase in response to the tasks. Also the saliva flow rate increased. This response was most pronounced in the aged and during the CWT. The average electromyogram varied significantly between age groups and tasks, with higher levels and shorter relative periods with gaps in the aged women and in the CWT. In addition, the peak activity of the jaw elevator muscles at mouse clicking was significantly elevated as a form of co-activation or attention-related activity. Conclusions: The study showed marked differences in the response to mental demands in aged as compared with young women. The mental stress, reflected by increases of salivary cortisol concentration, saliva flow rate, visual analogue scale ratings, and activity level of the jaw elevator muscles, was more pronounced in the aged women in response to the computer tasks.

Effect of aging on performance, muscle activation and perceived stress during mentally demanding computer tasks

“…In addition to the activation of the forearm muscles, also co-activation of the masseter and temporal muscles has been found during the computer tasks (30). This coactivation has been the most pronounced in elderly participants.…”

Impact of refreshing perception on mood, cognitive performance and brain oscillations: An exploratory study

“…Of all taste qualities, sour taste induces secretion of the largest volume of saliva by salivary glands (Hodson & Linden, 2006). Increase of saliva flow rate and salivary cortisol concentration has been observed in response to mental stress induced by cognitive activity (Bakke et al, 2004). Acute exposure to stress, such as the one triggered by a cognitive demand or challenge, may act as a mood enhancer and cognitive facilitator (Duncko, Cornwell, Cui, Merikangas, & Grillon, 2007;Sandi & Pinelo-Nava, 2007).…”

Effects of physical and mental task demands on cervical and upper limb muscle activity and physiological responses during computer tasks and recovery periods

“…Garde et al (2002) and Wahlström et al (2002) found that blood pressure increased when a mental stressor was added to the computer tasks. Other studies indicated that the cortisol level showed an upward trend after performing stressful tasks such as a two-choice reaction-time test (Nilsen et al 2007) and modiWed Stroop colour-word test (Bakke et al 2004).…”

“…The common typing tasks used in the laboratory studies involved typing of paragraphs of texts (McLean and Urquhart 2002;Johnston et al 2008;Wahlström et al 2002) or typing of numbers with or without mental calculations (Finsen et al 2001;Lundberg et al 2002;Schleifer et al 2008), or both (Hughes et al 2007). The Stroop colour word test is also a common method used to induce mental stress (Bakke et al 2004;Johnston et al 2008;Lundberg et al 2002;), whilst others used a twochoice reaction task for inducing high cognitive demand (Bansevicius et al 1997;Nilsen et al 2007). Recent investigations on mental stress have used a mental arithmetic task Schleifer et al 2008) or task with cognitive (memory) demands (Nilsen et al 2007).…”