Cardiovascular and immune responses to acute psychological stress in young and old women: a meta-analysis

OBJECTIVE

To describe the relationships between cardiovascular and natural killer (NK) cell number changes on acute psychological stress in women.

METHOD

Data from eight different studies were analyzed. A total of 128 healthy female subjects, 85 younger (18-45 years) and 43 older (49-87 years), had been subjected to a speech stressor (N = 80) or a mental effort stressor (N = 48), mental arithmetic, or the Stroop test. Correlations between changes in NK cell numbers, systolic (SBP) and diastolic (DBP) blood pressure, and heart rate (HR) were computed. Meta-analysis programs were used to study correlations across studies and to examine whether correlations differed with stressors or age.

RESULTS

In all studies, significant increases over baseline were observed for each variable. Across studies, the mean weighted r between changes in HR, DBP, and SBP was medium (rw = .25) to large (rw = .64). A medium to large average correlation between HR and NK changes (rw = .37) was observed, whereas average correlations of changes in NK cell numbers with blood pressure changes were small to medium (rw < or = .23). Correlations between changes in NK cell numbers and cardiovascular variables were homogeneous across studies, whereas mutual correlations between cardiovascular variables were heterogeneous. One moderator variable showed itself: correlations between HR and DBP reactions were larger in studies with older than younger subjects.

CONCLUSION

NK cell changes and HR responses induced by acute stress in women are regulated, to some extent, by the same mechanisms. Neither the type of stressor nor age seem to be very important when considering correlations between NK cell and cardiovascular changes. This study integrates information about NK cell and cardiovascular responses in women that can be used as reference material in future studies.

Effects of relaxation training on glucose tolerance and diabetic control in type II diabetes

The present study examined the effects of progressive relaxation training and EMG biofeedback on acute glucose disposal in diabetic subjects, as measured by glucose tolerance and three other measures of diabetic metabolic control. Twenty subjects with non-insulin-using Type II diabetes took part in progressive relaxation training and EMG biofeedback in a pre-post treatment versus wait-list experimental design. Treatment effects were assessed on glucose tolerance along with three measures of diabetic control: fasting blood glucose, two-hour postprandial blood glucose, and fructosamine. Stress reduction and relaxation was assessed with two physiological measures and two subjective questionnaires. The training program produced significant reductions in stress, as measured by State Anxiety, and significant changes in physiological measures of muscle activity and skin conductance compared to the control condition. However, no changes were found in glucose tolerance (while practicing relaxation) nor in any of the three measures of general diabetic metabolic control. The major implication of this study is that relaxation training does not appear to directly improve diabetic control in mildly stressed non-insulin-using Type II diabetic patients.

Rapid changes in cellular immunity following a confrontational role-play stressor

Recent laboratory studies have shown several immune system changes consistently associated with brief stress including increases in circulating natural killer (NK) cell numbers, increases in NK cell cytotoxicity (NKCC), increases in suppressor cytotoxic (CD8) T cell numbers, and decreases in the in vitro proliferative response to mitogen stimulation. In the present study, we use a confrontational role-play, which brings out responses varying from assertion to capitulation and examine the psychological, behavioral, physiological, and immune system responses to this task compared to a resting control task. Compared to the control condition, the brief confrontational role-play led to significant subjective and physiological arousal and increases in circulating NK (CD16, CD56) as well as large granular lymphocyte (CD57) cells and suppressor/cytotoxic T cells (CD8). There were also significant relationships between stress-related increases in the cardiovascular measures and the numbers of circulating NK cells. These findings support sympathetic nervous system activation as a primary mechanism for increases in NK cell numbers under challenge. These role-play results are generally consistent with those from other laboratory tasks such as mental arithmetic. However, in contrast to previously examined brief stressors, the role-play led to decreased NKCC adjusted for percentage of NK cells. This apparent differential change in NK cytotoxicity across different types of activating experimental tasks points to the importance of examining dimensions of the behavioral and emotional response to challenge or threat in addition to that of autonomic arousal.

The effects of the opiate antagonist naloxone on measures of cellular immunity during rest and brief psychological stress

This study investigated subjective, cardiovascular, and cellular immune system responses in 20 healthy young men during brief mental arithmetic stress compared with a video-watching control task. The role of endogenous opioids in mediating the immunological change to stress was examined by pre-task administration of the opiate antagonist naloxone. Immune changes were followed over a 1 hr post-task period. The results indicate significant physiological arousal and subjective distress as well as increases in NK cell cytotoxicity, numbers of circulating CD8 suppressor/cytotoxic T cells and NK lymphocytes following mental arithmetic but not the control task. Immune measures generally returned to baseline by 1 hr after the stress. Naloxone did not block the increase in NK cell activity or cell numbers following the stressor and had no effect on the other physiological or subjective measures. Thus, the results do not support endogenous opioids as a primary mechanism for immune changes to this type of acute stress. Naloxone did, however, increase NK cell cytotoxicity during the video task without effecting NK cell numbers, suggesting naloxone itself can increase per-cell NK cytotoxicity. Affective ratings for the week preceding testing were inversely related to the increase in NK cell numbers during mental arithmetic. If the increase in NK cell numbers under brief stress is part of an adaptive response to potential injury, then our data suggest that increases in general distress may impede normal immune system adaptation. Acute stress paradigms may be used as potential probes for investigations of individual differences in immune system responsivity.

Acute autonomic responses to postural change, Valsalva maneuver, and paced breathing in older type II diabetic men

PURPOSE

To examine the effects of advanced age and diabetes on the response to standard tests of cardiovascular reflexes.

DESIGN

Group comparison.

SETTING

Psychophysiology laboratory, Department of Veterans Affairs Medical Center.

PATIENTS

Sixteen elderly male (67-81 years old) non-insulin dependent diabetic subjects without hypertension and nine elderly male (63-77 years old) controls.

MAIN OUTCOME MEASURES

Continuous (beat-by-beat) measures of heart rate, systolic blood pressure, diastolic blood pressure, and skin conductance were studied during tests of Valsalva maneuver, deep breathing, and postural change from sitting to standing.

RESULTS

In comparison with elderly controls, the diabetic patients showed altered cardiovascular responses in measures of heart rate variability during Valsalva and standing. None of the subjects evidenced frank postural hypotension, but there was a greater fall in diastolic blood pressure immediately after standing for the diabetic patients compared with the controls. There was also a significant relationship between this response and decreased heart rate variability during Valsalva.

CONCLUSIONS

Older type II diabetic patients compared with healthy controls had mild cardiovascular abnormalities. These results parallel those of studies comparing younger diabetics and controls.

Immunological changes in young and old adults during brief laboratory stress

Few data are available on the response of the human immune system to acute psychological stressors under controlled laboratory conditions. Young female subjects (21-41 years) showed increases in natural killer (NK) cell activity, and in the numbers of circulating CD8 suppressor/cytotoxic T cells, and natural killer lymphocytes following a brief (12 minute) stressful mental arithmetic examination. Older female subjects (65-85 years) failed to show the stress-related increase in NK activity. The psychological stress did lead to increases in the numbers of circulating CD8 suppressor/cytotoxic T cells and NK lymphocytes in old subjects to a similar degree as that seen in the young group. No changes in the numbers of helper/inducer T cells (CD4), total T cells (CD3), or B cells (CD20) were found following the stressor for either group. Cardiovascular, catecholamine, and subjective stress responses were similar for the two age groups. These results demonstrate that brief psychological stress is associated with some rapid immune cell changes, including release of CD8 suppressor/cytotoxic T cells and NK cells into circulation, and in young subjects, increases in NK activity. The absence of an NK activity increase in the older subjects indicates that NK cell mobilization and cell lysis induced by NK cells may be differentially affected by stress. The results also suggest the possibility of an age-related deficit in the up-regulation of NK activity under some environmental demands.

Physical therapists' knowledge of sexuality of adults with spinal cord injury

Helping the adult with spinal cord injury to adjust to sexual limitations is an important and neglected part of his rehabilitation. Health professionals of all fields have been perceived to be deficient in their knowledge of the sexuality of the adult with spinal cord injury. A test with 40 statements reflecting myths, misconceptions, and truths about the effect of spinal cord injury on sexual function was administered to 30 physical therapists responsible for rehabilitating these adults. At least 28 of the 40 items were missed by 10 percent or more of the therapists. Experience and participation in educational programs appeared to contribute to the respondents' knowledge, as reflected by the test, but only experience was a statistically significant variable.