Stroop Color-word Conflict Test Research Articles

Anticholinergic burden and the cognitive functions in elderly and senile patients with arterial hypertension

The aim of the study was to evaluate the effect of anticholinergic load (AHN) on cognitive functions (CF) in elderly and senile multimorbid patients with arterial hypertension (AH).Materials and methods. 330 patients aged 60 years and older with essential AH were included in the study (median age 79 [72; 84] years, 158 (51 %) of women). All the patients were underwent the assesment of CF using the Montreal Cognitive Assessment Scale (MoCA), Mini-Mental Status Scale (MMS), Alzheimer’s Disease Assessment Scale-Cognitive (ADAS-cog), Trial Making Test (TMT), Digit Symbol Substitution Test (DSST), Verbal Association Test (literal (letter) and categorical (animal) associations), Boston Naming Test (BNT), Word-Color Interference Test, Stroop colorword conflict test. The anticholinergic load was determined using the anticholinergic load scale (Anticholinergic Cognitive Burden Scale, ACB).Results. Compared with patients who do not take anticholinergic drugs, multimorbid elderly and senile hypertensive patients with 2 or more points on the ACB scale had significantly lower final scores on the MoCA test (23 [21; 24.3] versus 24 [22; 25] points, respectively, p=0.042) and on MMSE (26 [24; 29] vs. 27.5 [25; 29] points, respectively, p=0.015), they spent statistically more time completing part B of the TMT test (217.5 [187.3; 246.3] vs. 204 [166.8; 247.3] seconds, respectively, p=0.038). The difference between the execution time of part B and part A of the TMT test in patients with 2 or more points on the ACB scale was statistically significantly greater than in patients with 0 points on this scale (141 [103.8; 168.5] versus 124 [83.8; 162] sec, respectively, p=0.034). Age, gender, education, and the structure of concomitant diseases did not differ between the groups.Conclusion. The results obtained indicate the adverse effect of аnticholinergic вurden on CF of multimorbid elderly and senile hypertensive patients and dictate the need to optimize pharmacotherapy in this category of patients.

Differential control of sympathetic outflow to muscle and skin during physical and cognitive stressors

PurposeSympathetic nerve activity towards muscle (MSNA) and skin (SSNA) regulates various physiological parameters. MSNA primarily functions in blood pressure and flow, while SSNA operates in thermoregulation. Physical and cognitive stressors have been shown to have effects on both types of sympathetic activity, but there are inconsistencies as to what these effects are. This article aims to address the discrepancies in the literature and compare MSNA and SSNA responses.MethodsMicroelectrode recordings were taken from the common peroneal nerve in 29 participants: MSNA (n = 21), SSNA (n = 16) and both MSNA and SSNA (n = 8). Participants were subjected to four different 2-min stressors: two physical (isometric handgrip task, cold pressor test) and two cognitive (mental arithmetic task, Stroop colour–word conflict test), the latter of which saw participants separated into responders and non-responders to the stressors. It was hypothesised that the physical stressors would have a greater effect on MSNA than SSNA, while the cognitive stressors would operate conversely.ResultsPeristimulus time histogram (PSTH) analysis showed the mental arithmetic task to significantly increase both MSNA and SSNA; the isometric handgrip task and cold pressor test to increase MSNA, but not SSNA; and Stroop test to have no significant effects on changing MSNA or SSNA from baseline. Additionally, stress responses did not differ between MSNA and SSNA in participants who had both sets of data recorded.ConclusionsThis study has provided evidence to support the literature which claims cognitive stressors increase sympathetic activity, and provides much needed SSNA data in response to stressors.

No Sex Difference in Mental Fatigue Effect on High-Level Runners' Aerobic Performance.

Some evidence suggests that sedentary women may be more vulnerable to cognitive task-induced mental fatigue. Mental fatigue, in turn, may worse aerobic exercise performance, presumably via increased perceived effort. However, it remains unclear whether acute mental fatigue induction increases perceived effort and worsens endurance performance in high-level professional athletes and whether such effects are influenced by sex. We studied 30 athletes (15 women and 16 men) in a single-blinded, randomized, controlled and crossover protocol. In separate visits, athletes either performed a 45-min cognitive task (Stroop's color-word conflict test) to induce mental fatigue or watched a 45-min documentary as control. Then athletes performed a time-to-exhaustion test on a treadmill. Perceptual measures and cognitive performance indicated that the prolonged cognitive task induced a similar mental fatigue state in women and men. Cardiorespiratory and metabolic responses to the TEE did not change with mental fatigue in both sexes. Mental fatigue increased perceived effort during the time-to-exhaustion test, anticipated attainment of maximal effort, and shortened time to exhaustion similarly in women and men (mean ± SE, -27.3 ± 20.9 s for women vs -26.7 ± 15.1 s for men; P = 0.98). The prolonged cognitive task provoked mental fatigue, anticipated attainment of maximal perceived effort, and worsened aerobic performance in professional runners with no sex differences. Although we did not contrasted athletes with nonathletes, our results suggest that being an athlete may somehow prevent women from developing greater mental fatigue and suffering more from its underlying effects compared with men.

Effects of Antihypertensive Drugs on Skin Blood Flow as an Indicator of Sympathetic Responses to Mental Stress in Hypertensive Patients

The aim of this study was to clarify the response of sympathetic activity to antihypertensive drugs using a mental stress test in hypertensive patients and to determine the effects of antihypertensive drugs on the sympathetic activitymediated hemodynamic response to mental stress. Hypertensive patients were divided into three groups according to the type of drug(s) being taken: a calcium antagonist group, an angiotensin II receptor blocker group, and a combination therapy group of calcium antagonists and angiotensin II receptor blockers. The Stroop color-word conflict test was applied as a mental stress test and hemodynamic responses to mental stress were measured, including blood pressure, pulse rate, and skin blood flow. Elevation of blood pressure by mental stress was suppressed in the combination therapy group compared with the calcium antagonist group. Reduction of skin blood flow by mental stress was suppressed in both the angiotensin II blocker group and the combination therapy group compared with the calcium antagonist group. In conclusion, skin blood flow can be a useful tool to evaluate sympathetic activity and combination therapy with calcium antagonists and angiotensin II receptor blockers were the most useful therapy for suppressing the hemodynamic response to mental stress.

Attenuated NOx responses and myocardial ischemia, a possible risk for structural vascular disease in African men: the SABPA study

Chronically elevated blood pressure has been associated with impaired NO-mediated vasodilation and structural vascular disease risk. This study aimed to determine whether significant associations exist regarding NO metabolite (NOx) responses, cardiovascular function and structural vascular disease in a cohort of African and Caucasian men. The study included 81 African and 94 Caucasian male teachers stratified via median splits into low and high NOx ethnic groups. Ambulatory blood pressure, electrocardiogram monitoring and ultrasound carotid intima-media thickness (CIMT) images were obtained. Cardiovascular measurements and fasting blood for NOx responses were measured during rest and on challenging the cardiovascular system with the Stroop colour-word conflict test. African men displayed significantly higher resting NOx as well as higher number of 24 h silent ischemic events than their Caucasian counterparts. Low NOx African men displayed enhanced α-adrenergic and ECG ST segment depression acute mental stress responses as well as 24 h silent ischemic events associated with CIMT (adjusted R(2) = 0.47; β = 0.25; confidence interval (CI) = 0.13, 0.41). African men demonstrated a vulnerable cardiovascular profile. Novel findings revealed α-adrenergic-driven blood pressure responses and less NO bioavailability during acute stress. The association between myocardial ischemia and CIMT in this group emphasized their risk for future coronary artery disease and cerebrovascular events.

Evaluation of mental stress by physiological indices derived from finger plethysmography

BackgroundQuantitative evaluation of mental stress is important to prevent stress-related disorders. Finger plethysmography (FPG) is a simple noninvasive method to monitor peripheral circulation, and provides many physiological indices. Our purpose is to investigate how FPG-derived indices reflect on mental stress, and to clarify any association between these physiological indices and subjective indices of mental stress.MethodsThirty-one healthy women (mean age, 22 years ± 2) participated. The participants rested by sitting on a chair for 10 min. They then performed a computerized version of the Stroop color-word conflict test (CWT) for 10 min. Finally, they rested for 10 min. FPG was recorded throughout the experiment. The participants completed a brief form of the Profile of Mood States (POMS) questionnaire before and after the test. Using the FPG data, we conducted chaos analysis and fast Fourier transform analysis, and calculated chaotic attractors, the largest Lyapunov exponent, a high-frequency (HF) component, a low-to-high-frequency (LF/HF) ratio, finger pulse rate and finger pulse wave amplitude.ResultsThe HF component decreased and the LF/HF ratio increased significantly during the test (P < 0.01), while the confusion subscale of POMS increased after the test (P < 0.05). During testing, finger pulse rate significantly increased (P < 0.001), and the finger pulse wave amplitude decreased (P < 0.001). The attractor size reduced during testing and returned to a baseline level afterwards. Although the largest Lyapunov exponent showed no significant change during testing, significant negative correlation with the tension-anxiety subscale of POMS was observed at the beginning (P < 0.01). A significant negative correlation between the LF/HF ratio and two subscales was also observed in the beginning and middle of the test (P < 0.05). There were no correlations during the rest periods.ConclusionsThe physiological indices derived from FPG were changed by mental stress. Our findings indicate that FPG is one of the easiest methods to evaluate mental stress quantitatively. In particular, the largest Lyapunov exponent and the LF/HF ratio might be associated with acute mental stress. Farther examination is needed to find any association between the physiological indices and various types of mental stress.

Procoagulant reactivity to laboratory acute mental stress in Africans and Caucasians, and its relation to depressive symptoms: The SABPA Study

The risk of cardiovascular disease is dramatically increasing in Africans (black). The prothrombotic stress response contributes to atherothrombotic disease and is modulated by depressive symptoms. We examined coagulation reactivity to acute mental stress and its relation to psychological well-being in Africans relative to Caucasians (white). A total of 102 African and 165 Caucasian school teachers underwent the Stroop Color-Word Conflict test. Circulating levels of von Willebrand factor (VWF) antigen, fibrinogen, and D-dimer were measured before and after the Stroop. Cardiovascular reactivity measures were also obtained. All participants completed the Patient Health Questionnaire-9 and the General Health Questionnaire-28 for the assessment of depressive symptoms and total psychological distress, respectively. After controlling for covariates, resting levels of VWF, fibrinogen, and D-dimer were higher in Africans than in Caucasians (all p-values ≤0.006). Depressive symptoms and psychological distress were not significantly associated with resting coagulation measures. Stress reactivity in VWF (p<0.001) and fibrinogen (p=0.016), but not in D-dimer (p=0.27), were decreased in Africans relative to Caucasians with Africans showing greater reactivity of total peripheral resistance (p=0.017). Depressive symptoms, but not general psychological distress, were associated with greater VWF increase (p=0.029) and greater fibrinogen decrease (p=0.030) in Africans relative to Caucasians. In conclusion, Africans showed greater hypercoagulability at rest but diminished procoagulant reactivity to acute mental stress when compared with Caucasians. Ethnic differences in the vascular adrenergic stress response might partially explain this finding. Depressive symptoms were associated with exaggerated VWF reactivity in Africans relative to Caucasians. The clinical implications of these findings for Africans need further study.

Exploring the Link Between Cardiovascular Reactivity and End-Organ Damage in African and Caucasian Men: The SABPA Study

Heart failure in the African population is reaching alarming levels. Increased afterload as a result of increased vasoconstriction during stress may lead to impaired ventricular function and stroke volume (SV) as well as vascular hypertrophy. In this study, we challenged the cardiovascular system in order to evaluate the possible contribution of indicators of α-adrenergic vasoconstriction (i.e., vascular resistance and SV reactivity) on left ventricular mass and carotid intima-media thickness (CIMT) in African and Caucasian men. We evaluated 101 African and 101 Caucasian male schoolteachers. Ambulatory blood pressure measurements were taken. Total peripheral resistance, Windkessel compliance and SV, and resting and reactivity values were obtained using a Finometer device while the Stroop color word conflict test was being applied. The electrocardiogram was recorded to obtain the Cornell product as indication of left ventricular mass. The CIMT was measured and the cross-sectional wall area (CSWA) calculated. African men showed higher total vascular resistance resting values as well as higher positive reactivity values compared with Caucasian men. The SV decreased significantly during stress in African men while resting blood pressure and the Cornell product value increased. SV showed a consistent association with left ventricular mass (β = -0.21; P = 0.04) and CSWA (β = -0.24; P = 0.01) in single and multiple regression analyses. No such associations were evident in the Caucasian men. African men showed a suppressed SV, possibly as a result of an increased ventricular afterload leading to end-organ damage.

609 COMPARING THE ASSOCIATION OF CARDIOVASCULAR REACTIVITY AND END-ORGAN DAMAGE IN AFRICAN AND CAUCASIAN MEN

Objectives: The cardiovascular system was challenged to evaluate the possible contribution of vascular resistance and stroke volume reactivity on left ventricular mass and intima-media thickness, in both African and Caucasian men. Increased afterload as a result of increased vascular resistance may lead to impaired stroke volume and vascular and/or ventricular hypertrophy. Methods: We included 101 African and 101 Caucasian men. Ambulatory 24-hour blood pressure measurements were conducted. Vascular resistance, compliance and stroke volume resting and reactivity values were obtained during the application of the Stroop color word conflict test. Left ventricular mass was determined using the Cornell product. The carotid-intima media thickness was obtained and the cross-sectional wall area (CSWA) calculated. Results: In African men it was found, besides higher blood pressure, PWV and Cornell product values, that vascular resistance showed higher resting values as well as positive reactivity values. Stroke volume reactivity was suppressed in African men as well as vascular compliance. Diastolic blood pressure reactivity was also higher in Africans. Stroke volume showed a consisted association with markers of end-organ damage only in African men namely with left ventricular mass and CSWA in partial (Cornell product: r= -0.22; P=0.05; CSWA: r= -0.26; P=0.02) and multiple regression analysis (Cornell product: Adjusted R2=0.15, B=-0.701, P=0.04; CSWA Adjusted R2=0.28, B=-0.077, P=0.01). Conclusion: African men showed an increased vascular resistance reactivity accompanied by an impaired stroke volume reactivity, that indicate restricted ventricular function. For the same age the African men showed a decrease in ventricular function.

Effects Of Exercise Training On Endothelial Function And Vascular Responses During Stress In Female Smokers

There is longitudinal evidence that increased physical activity and/or exercise reduces the risk of morbidity and mortality associated with cardiovascular disease in female smokers. It is plausible that the mechanism responsible for the reduced risk is improved vascular health and reduced hyper-reactivity to a neurovascular stressor. PURPOSE: To determine the benefits of 3 weeks of aerobic exercise training on endothelial function, measured by flow-mediated dilation (FMD), and cardiovascular responses to neurovascular stress among sedentary female smokers and non-smokers. METHODS: Thirty-five participants were recruited. Non-smokers were randomly assigned into the exercise training (n=12) or to the passive rest group (n=12). All regular smokers underwent (n=11) the exercise training protocol. FMD and stress responses were measured before and after a 3 week moderate intensity (∼50%VO2max) aerobic exercise training program. FMD was determined by brachial arterial velocity, arterial diameter, and blood flow measured by Doppler Ultrasonography. Those measures and beat-to-beat finger blood pressure (BP), and heart rate (HR) were assessed in responses to 2 min of forehead cold and 4 min of the Stroop Color-Word conflict test (CWT) (separated by 8 min of rest) at baseline and three weeks later. RESULTS: Compared to non-smokers, FMD was impaired (5.98 ± 3.27 vs. 4.55 ± 4.18, p=0.04) and decreases in arterial diameter (-0.10 ± 0.08 vs. -0.04 ± 0.07; p=.03) and blood flow (-81.69 ± 49.51 vs. -45.12 ± 27.46; p=.05) responses during forehead cold were augmented at baseline among female smokers. Three weeks of cycle exercise training at a moderate intensity did not improve endothelial function measured by FMD or alter stress reactivity during neurovascular stress in smokers or non-smokers. CONCLUSIONS: Based on these results, the impact of 3 weeks of moderate intensity exercise training was insufficient to observe a measurable change in endothelial function or cardiovascular responses during stress.

Acute exercise improves endothelial function despite increasing vascular resistance during stress in smokers and nonsmokers

The present study examined the effect of acute exercise on flow mediated dilation (FMD) and reactivity to neurovascular challenges among female smokers and nonsmokers. FMD was determined by arterial diameter, velocity, and blood flow measured by Doppler ultrasonography after forearm occlusion. Those measures and blood pressure and heart rate were also assessed in response to forehead cold and the Stroop Color-Word Conflict Test (CWT) before and after 30 min of rest or an acute bout of cycling exercise (∼50% VO₂ peak). Baseline FMD and stress responses were not different between smokers and nonsmokers. Compared to passive rest, exercise increased FMD and decreased arterial velocity and blood flow responses during the Stroop CWT and forehead cold in both groups. Overall, acute exercise improved endothelial function among smokers and nonsmokers despite increasing vascular resistance and reducing limb blood flow during neurovascular stress.

A Comparison of Cognitive Performance Decreases During Acute, Progressive Fatigue Arising From Different Concurrent Stressors

Fatigue is known to impair cognitive performance, but it remains unclear whether concurrent common stressors affect cognitive performance similarly. We used the Stroop Color-Word Conflict Test to assess cognitive performance over 24 hours for four groups: control, sleep-deprived (SD), SD + energy deficit, and SD + energy deficit + fluid restricted. Fatigue levels were quantified using the Profile of Mood States (POMS) survey. Linear mixed-effects (LME) models allowed for testing of group-specific differences in cognitive performance while accounting for subject-level variation. Starting fatigue levels were similar among all groups, while 24-hour fatigue levels differed significantly. For each cognitive performance test, results were modeled separately. The simplest LME model contained a significant fixed-effects term for slope and intercept. Moreover, the simplest LME model used a single slope coefficient to fit data from all four groups, suggesting that loss in cognitive performance over a 24-hour duty cycle with respect to fatigue level is similar regardless of the cause.

Emotion Self-Regulation, Psychophysiological Coherence, and Test Anxiety: Results from an Experiment Using Electrophysiological Measures

This study investigated the effects of a novel, classroom-based emotion self-regulation program (TestEdge) on measures of test anxiety, socioemotional function, test performance, and heart rate variability (HRV) in high school students. The program teaches students how to self-generate a specific psychophysiological state--psychophysiological coherence--which has been shown to improve nervous system function, emotional stability, and cognitive performance. Implemented as part of a larger study investigating the population of tenth grade students in two California high schools (N = 980), the research reported here was conducted as a controlled pre- and post-intervention laboratory experiment, using electrophysiological measures, on a random stratified sample of students from the intervention and control schools (N = 136). The Stroop color-word conflict test was used as the experiment's stimulus to simulate the stress of taking a high-stakes test, while continuous HRV recordings were gathered. The post-intervention electrophysiological results showed a pattern of improvement across all HRV measures, indicating that students who received the intervention program had learned how to better manage their emotions and to self-activate the psychophysiological coherence state under stressful conditions. Moreover, students with high test anxiety exhibited increased HRV and heart rhythm coherence even during a resting baseline condition (without conscious use of the program's techniques), suggesting that they had internalized the benefits of the intervention. Consistent with these results, students exhibited reduced test anxiety and reduced negative affect after the intervention. Finally, there is suggestive evidence from a matched-pairs analysis that reduced test anxiety and increased psychophysiological coherence appear to be directly associated with improved test performance--a finding consistent with evidence from the larger study.

Acute Exercise Improves Endothelial Function Despite Increasing Vascular Resistance During Stress in Smokers and Non-smokers

Endothelial dysfunction, measured by flow mediated dilation (FMD), and hyper-reactivity to neurovascular challenges are two potential mechanisms by which cigarette smoking can be harmful to the vasculature. It has been suggested that acute exercise may improve endothelial function and attenuate cardiovascular reactivity to neurovascular stressors, but we could not locate studies of female smokers that examined FMD after neurovascular stress. PURPOSE: To determine the effect of an acute bout of moderate-intensity cycling exercise on FMD and cardiovascular responses during neurovascular stress among sedentary female smokers and non-smokers. METHODS: FMD was determined by brachial arterial diameter, arterial velocity and blood flow measured by Doppler ultrasonography after forearm occlusion. Those measures and beat-to-beat finger blood pressure (BP) and heart rate (HR) were also assessed in response to 2 min of forehead cold and 4 min of the Stroop Color-Word conflict test (CWT). Individuals participated in two counterbalanced conditions: 30 minutes of either passive rest or cycling exercise (∼50% VO2peak). FMD was tested 8 min after stress. RESULTS: Baseline FMD and stress responses were not different between smokers and non-smokers. Compared to passive rest, exercise increased FMD (7 ± 2% vs. 5 ± 2%) and resting HR; arterial velocity; and blood flow, and decreased resting SBP in both groups. During the Stroop CWT, arterial velocity (-9 ± 8 vs. 2 ± 2 cm/s) and blood flow (-53 ± 58 vs. 19 ± 38 ml/min) responses were reduced after exercise compared to passive rest in smokers and non-smokers. Similarly, during forehead cold, reductions in arterial velocity (-19 ± 11 vs. -4.5 ± 4.5 cm/s) and blood flow (-107 ± 74% vs. -25 ± 30 ml/min) responses were augmented after exercise compared to passive rest. CONCLUSIONS: Acute cycling exercise improved endothelial function among female smokers and non-smokers despite increasing vascular resistance and reducing limb blood flow during both dilatory and constrictive neurovascular stress in the presence of post-exercise hypotension.

Space motion sickness: The sensory motor controls and cardiovascular correlation

Space motion sickness: The sensory motor controls and cardiovascular correlation

Exposure to Bright Light Modifies HRV Responses to Mental Tasks during Nocturnal Sleep Deprivation

This study was intended to determine the effects of continuous bright light exposure on cardiovascular responses, particularly heart rate variability (HRV), at rest and during performance of mental tasks with acute nocturnal sleep deprivation. Eight healthy male subjects stayed awake from 21.00 to 04.30 hours under bright (BL, 2800 lux) or dim (DL, 120 lux) light conditions. During sleep deprivation, mental tasks (Stroop color-word conflict test: CWT) were performed for 15 min each hour. Blood pressure, electrocardiogram, respiratory rate, urinary melatonin concentrations and rectal temperature were measured. During sleep deprivation, BL exposure depressed melatonin secretion in comparison to DL conditions. During sleep deprivation, exposure to BL delayed the decline in heart rate (HR) for 4 h in resting periods. A significant increment of HR induced by each CWT was detected, especially at 03.00 h and later, under DL conditions only. In addition, at 04.00 h, an index of sympathetic activity and sympatho-vagal balance on HRV during CWT increased significantly under DL conditions. In contrast, an index of parasympathetic activity during CWT decreased significantly under DL conditions. However, the indexes of HRV during CWT did not change throughout sleep deprivation under BL conditions. Our results suggest that BL exposure not only delays the nocturnal decrease in HR at rest but also maintains HR and balance of cardiac autonomic modulation to mental tasks during nocturnal sleep deprivation.

Repressive Coping and Blood Measures of Disease Risk: Lipids and Endocrine and Immunological Responses to a Laboratory Stressor1

Relations between repressive coping and a variety of health‐related variahles including insulin, lipids, catecholamines, and cellular immune components, were investigated in a laboratory study of acute stress among a sample of healthy male college students (N ‐ 83). Compared to nonrepressors, at baseline, repressors had fewer numbers of circulating CD4 (T‐helper) cells, greater numbers of natural killer (NK) cells. lower high‐density lipoprotein (HDL), a higher total/HDL cholesterol ratio, and higher fasting insulin levels. In response to an acute laboratory stressor (Stroop Color Word Conflict Test). repressors demonstrated an attenuated increase in the number of circulating NK cells compared to nonrepressors. Confounds such as physical activity, age, and smoking were unrelated to the dependent measures.

Physical activity, mental stress, and short-term heart rate variability in patients with ischemic heart disease.

Among the general population, mental stress seems to depress heart rate variability (HRV), and physical activity level seems to be positively associated with HRV. However, the extent to which these relationships exist among patients with ischemic heart disease is not clear. Therefore, this study investigated the association between level of physical activity and HRV among patients with ischemic heart disease during conditions of paced breathing and the Stroop Color-Word Conflict Test (Stroop). Forty-two patients with ischemic heart disease were assigned to groups based on their documented volume of aerobic activity: Low = 1.008-2.646 kJ/wk; Mod = 3.024-3.864 kJ/wk; and High = 4.284-7.560 kJ/wk. These groups did not differ in age, body mass index, or hostility as determined by the Minnesota Multiphasic Personality Inventory. Time and frequency domain measures of HRV were derived from electrocardiograph data obtained during 5 minutes of paced respiratory control and 5 minutes of performing the Stroop Test. There was a main effect of activity level (P < 0.05) on the standard deviation of R-wave to R-wave intervals (SDNN), total spectral power, and high-frequency power such that these dependent variables were greater in the High group than in the Low or Mod group. Furthermore, there was a main effect of the test condition on SDNN and total power, both of which were lower during the Stroop Test as compared to paced respiratory control. The results indicate that, among patients with ischemic heart disease, a high level of physical activity is associated with higher HRV, but is not related to stress reactivity as measured by HRV.

Effects of Stroop color-word conflict test on the autonomic nervous system responses

The Stroop color-word test (CWT) is a mental stress test involving sensory rejection and has been used as a model of the defense reaction in humans. The present study was designed to investigate effects of CWT on resting cardiac autonomic nervous system activity evaluated by analyses of heart rate (HR) variability (HRV). Eight healthy subjects performed 21 min of CWT after 14 min of resting control followed by 14 min of recovery (RCV). Beat-to-beat R-R intervals (RRI, i.e., HRV), systolic blood pressure (SBP), and instantaneous lung volume were continuously monitored throughout these periods. Steady-state HRV data (10-12 min) for resting control and recovery (12 min) and for 1-11 min (CWT1) and 11-21 min (CWT2) of CWT were analyzed by coarse-graining spectral analysis to break down their total power into harmonic and nonharmonic (fractal) components. The harmonic component was further divided into low (0.0-0.15 Hz, LF)- and high (>0.15 Hz, HF)-frequency components. Cardiac sympathetic (SNS) and parasympathetic (PNS) nervous system activity indicators were evaluated as LF/HF and HF/TP, respectively [LF, HF, and total spectral power (TP) of HRV]. The fractal component had the spectrum of 1/f(beta), and the spectral exponent beta was calculated. RRI decreased and SBP, plasma norepinephrine, and epinephrine concentrations increased significantly (P < 0.05) in response to CWT (CWT1 and CWT2). PNS and SNS indicators did not show any significant (P > 0.05) difference between resting controls and CWT. Whereas the percentage of fractal components in total HRV remained unchanged, beta decreased significantly (P < 0.05) in response to CWT. Transfer magnitudes from SBP to RRI, calculated by cross-spectral analysis, decreased at CWT2. The transfer magnitudes from instantaneous lung volume to RRI were also decreased significantly (P < 0.05) by CWT. It was concluded that although CWT did not affect the SNS indicator of HRV, despite altered HR and vasomotor responses, tonic sympathetic nervous system influence was observed for norepinephrine and epinephrine. In addition, reflex blood pressure (CWT2) and respiratory modulation of HR (CWT1 and CWT2) decreased during CWT. Mental stress altered the fractal nature of HRV (as judged by decreased beta), but mechanism(s) responsible for this change remained unknown.

Spectral Analysis of Stress-Induced Change in Blood Pressure and Heart Rate in Normotensive Subjects

Changes in spectral analysis of the variability in systolic blood pressure (SBP) and heart rate (HR) were investigated in 12 normotensive volunteers during a well-standardized stress test. BP was measured indirectly from the finger by a noninvasive device (Finapres). The stress test was a computerized version of the Stroop color word conflict test (CWT). The influences of acute (single dose) beta 1-selective blockade by bisoprolol or angiotensin-converting enzyme (ACE) inhibition by lisinopril were analyzed by a double-blind placebo-controlled trial. During the placebo phase, the efficiency of the stress test was confirmed by a significant increase in SBP (25 +/- 11%), HR (36 +/- 23%), and plasma concentrations of epinephrine (Epi, 54 +/- 37%) and norepinephrine (NE, 27 +/- 35%). Stress induced a significant increase in the amplitude of SBP and HR oscillations in the medium-frequency band (MF, 70- to 140-mHz range), which corresponds to the Mayer waves (27 +/- 32 and 42 +/- 43%, respectively for SBP-MF and HR-MF). The stress-induced increase in NE correlated significantly with the increase in HR (r = 0.68, p < 0.05). The stress-induced increase in SBP-MF correlated significantly with the increase in Epi (r = 0.69, p < 0.05) and in HR-MF (r = 0.69, p < 0.05). A significant decrease in SBP-MF at rest was observed with a single oral (p.o.) dose of bisoprolol, but not of lisinopril. As a noninvasive method, spectral analysis of the variability in SBP and HR may be of benefit in stress-induced modifications of the autonomic nervous system.