PERCEIVED STRESS AND SALIVARY CORTISOL IN ...

PERCEIVED STRESS AND SALIVARY CORTISOL IN DAII.,Y LIFE 1,z

Maneen M. van Eck, M.S.c and Nancy A. Nicolson, Ph.D. University of Limburg

ABSTRACT Clarifying the nature of endocrine responses to chronic or intermittent stress in daily life requires repeated measurements oJstress, hormone levels, and emotional states. In this study, 42 High Stress(HS)and 46 Low Stress(LS)subjects were selected on the basis ofPerceived Stress Scale scoresfrom a largersample of male white-collar workers. Subjects completed self-reports [Experience Sampling Method(ESM)J and collected saliva samplesjor cortisol determination ten times a day overfive consecutivedays, incl:~ding three work and two non-work days. We test the hypothesis that high perceived stress is associated with elevated cortisol. The HS group scored higher than the LS group on measures of trail anziet}~, depression, anger, and psychosomatic complaints, as wel! as on ESM measures oJpositive and negative affect and stressful daily events. Although negative a}ject was higher and stressful events morefrequent on workdays than weekends (especially for HS subjects), no dijjerence in workday vs. weekend cortiso! levels was found in the subsample ofsubjects á with sujjrcienl data. On workdays, HS subjects had higher mean cortisol levels than LS subjects at each ofthe ten sampling times between 8 a.m. and 10 p.m. (repeated measures ANOVA, p < .02). Mean workday conisol wcu correlated with higher trait anxiety, depression, and the low arousal ~fimension ofESM neg_ ative a,~ect. (Ann Behav Med

199A, 163):221-227)

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INTRODUCT7[ON Over the last 20 years, a wide range of studies bas established an association between psychcsocial stress and a variety of psychological and physical disorders. The strengths of these associations aze usually small and inconsistent, but stressful life events, for instance, have been linked to depression, neurotic impairment, and other psychological symptomatology (1-3). Suess has also been linked empirically with increased susceptibility to infectious disease (4), with other immune-related disorders like recurrences of herpes infections (5) and asthmatic exacerbations (6), with coronary heart disease (7), and with di-

'We thank Dr. J. Sulon, University of Liege, for performing RIA ana]yses of salivary cortisol, and C. Dijlanan for assistance in all aspecu of the study. '..Funding was provided by the Netherlands Organization for Scientific t Research(NWO)and the University of Limburg. Reprint Address: M. M.van Eck, Social Psychiatry Section, Department of Psychiatry and Neuropsychology, University of Limburg, P.O. Box 616, 6200 MD Maastricht, the Netherlands. '~;";

m .1994 by The Society of Behavioral Medicine.

abetes mellitus(8). The diversity ofstress concepts and research methodologies used in these studies makes it difficult to integraté all of the findings. Since the beginning of this century, the endocrine system has received much attention in stress research (9,10) with an emphasis on the hypothalamicpituitary—adrenal (HPA) axis. This system forms a theoretically promising pathway for mediating the relationships between psychosocio] stress and subsequent disorder (1 1). Cortisol secretion appears to play an important role in the regulation of physiological and behavioral responses under stressful situations (12,13j. Cortisol increases after strenuous physical exercise(14)and mental task load, speci5cally in response to distress as opposed to effort or general arousal (15,16). Cortisol is also the most important glucocorticoid, with the potential of exerting its effects on practically all cells and tissues. Some of the most important effects of cortisol are stimulation ofgluconeogenesis,inhibition ofglucose uptake, suppression ofinflammation,and suppression of numerous inimune functions. Glucocorticoids almost invariably suppress rather than enhance biological defense mechanisms. They are thought to protect against the normal defense reactions that are activated by stress by preventing these defense reactions from overshooting and by preserving the specificity of immune reactions (17). Indeeà, moss of the physiological reactions to stress are thougt-~t to b:, adaptive, i.e. they counter the effects of physical stress (trauma, bleeding), or are seen as a preparation íor fight or flight responses to acute danger (18). The question now is, why and when could this adaptive mechanism be a pathway to disease? There are indications that the same suppressive effects of glucocorticoids on several functions of the immune system may leave a subject more susceptible to infections or even tumors(19). Other studies indicate that increased levels ofcortisol may be involved in the etiology ofcoronary heart diseases (20). The general idea is that stress causes an overproduction ofantiinflammatory and immune suppressive actions, leading to adverse consequences (e.g. breakdown of the immune system) (21,22). There is also evidence from animal studies for a gradual loss ofadaptation within the pituitary-corticoadrenal response. Ifstress is prolonged, hypophyseal receptors appear to lose their sensitivity to cortisol,and as a consequence, prolonged increases in cortisol tend to further slow the recovery of wrtisol after stress because of the ineffectiveness of the negative feedback loop (23,24). Recent theoretical overviews by Henry and Stephens (25) and Siegrist (26) are more or less in line with this concept of loss of adaptation. It is reasonable to assume that stress reactions will only lead todisease when they are prolonged or occur. very often. The effects of chronic or .internuttent stress on the HPA-axis, however, have received far less attention in the literature than the effects of acute suessors, and studies on naturally occurring stressors and their effects are even more rare. Data on cortisol levels during chronic psychosocial stress are inconsistent, wíth

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enhanced as well as decreased concentrations repoRed,and large variability among individuals. Elevated levels of cortisol were found in subjects living near the damaged nuclear power plant at Three Mile Island (27). Higher levels of urinary coRisol correlated significantly with urinary catecholamines, self-reports of physical and mental symptoms, and decrements in task performance. Astudy following parents ofleukemic children into the period of bereavement for as long as three years after the death ofthe child showed that l 7-hydroxycoRicosteroid excretion rates were related to the effectiveness of subjects' psychological defenses (28,29). Elevated levels of plasma and salivary cortisol were found in Iran hostages after release from captivity, reflecting distress, anxiety, and elation. Salivary cortisol was the only physiological measurement that demonstrated a significant correlation with psychiatrists' ratings ofthe hostages' psychological disturbance (30). The above studies have examined stress under rather extreme or unusual situations. With respect to more normal settings, studies of air traffic controllers suggest that occupational stress is associated with increased cortisol production (31,32). Caplan et al. (33) studied white-collar workers in a relatively everyday organizational setting. While there was no main effect of work load or personality traits on mean cortisol, high perceived work load was associated with lower morning coRisol values. The results presented here are part of a larger study concerningemotional and hormonal responses[o naturally occuring stress in daily life. Stress is cuirentiy conceptualized as a dynamic process, whi~•h changes over time and in relation to the environment. It is therefore necessary to include repeated measurements of stress, hormone levels, and emotional states to investigate the stress—hormone relationship. This relationship should ideally be studied in naturalistic settings and over time, so that we can begin to understand how adaptation occurs in response to intermittent daily hassles in individuals who are observed in their normal social networks,settings,and activities (34). For these reasons, we chose to use two relatively new techniques, Experience Sampling Method (ESM)(35,36) and monitoring of salivary cortisol (37), to assess the relationship between an indiviáual's affective state and neuroendocrine changes over time. Subjects were selected on the basis of PerceivedStress Scale scores(3H)from a large sample of male whitecollar workers and were then monitored during their daily activities. Subjects completed self-repoRs (ESM) and collected saliva samples for cortisol determination at semi-random intervals ten times a day over five consecutive days, including three work and two non-work days. We test the hypothesis that high perceived stress is associated with elevated cortisol, either in general, or during certain phases of the circadian cycle or certain days of the week (e.g. work versus non-work days). With respect to diurnal patterns, no specific hypothesis was formulated. The few studies in which conisol has been measured at more than one time of day in healthy subjects report significant relationships between cortisol and psychological trait measures at some time points and not at others. For example, in a large German survey study in which salivary cortisol was measured three times on a single day, only 8 a.m. levels showed clear associations with psychological and demographic variables(39).In a similar fashion, perceived work load had an effect on cortisol levels in white-collar workers that was dependent on the time of day when blood was sampled (33), and hostility was associated with high cortisol in daytime,

van Eck and Nicolson but not in evening or overnight urine samples (40). Depressive symptoms could also be related to increased coRisol secretion at specific times ofthe day. Concerning day-of-the-week effects, we hypothesized that cortisol would be elevated on workdays compared to the weekend,possibly in interaction with perceived stress. Although- subject groups were selected according to a global measure of stress and not on the basis of work-related stress, we reasoned that work might be a major source of stress. Studies by Frankenhaeuser and colleagues (41) have demonstratedthat cardiovascular and neurcendocrine activity are higher at work than at home, and that slow recovery of responses, or "unwinding," after work might represent along-term health risk. Finally, we examined the extent to which psychological variables (trait amciety, depression, anger, and psychosomatic complaints; ESM measures of mood and stressful events) might contribute to individual differences in workday cortisol level. SUBJECTS Local industries and government agencies were approached via their personnel departments to participate in the study. A decision as to which categories of employees fell under the defiiution:of "white-collar" was made by each personnel department on the basis of standard job function descriptions. Questionnaireswere distributed among these employees,accompanied by a letter explaining the goals of the study. Participation was voluntary, and care was taken to insure anonymity. Three hun3red sixteen male employees from six different industries or agencies completed the screening questionnaire. The mean score on !hc Perceived Stress Scale(PSS)for this sample was 12.7 (sd = 6.i1), similar to U.S. norms(mean 13.02, sd = 6.45)(38). Ninety-two subjects with scores in the upper or lower tertiles of the screening sample distribution (PSS-10 score _ 1 b) were recruited to participate in the study, excluding any individuals with a history of endocrine disorder, medications known to affect cortisol levels, psychopathology(major affective disorder, psychoses), or currently in treatment for mental health problems. High- and low-stress subjects were matched for age group, marital status, and household composition. Because it was not possible to match all subjects, numbers of subjects in the final two groups differ slightly. Four subjects failed to meet Experience Sampling compliance criteria (see Daily Experience section, below) and were therefore excluded from further analysis. Of the 88 remaining subjects, 42 subjects comprised the High-Stress(HS)group and 46 subjects the Low-Stress(LS)group. Mean age was 42.1 years (range 27 to 57 years), with no significant difference between the two groups. Eighty-nine percent were marred,and 81%had children living at home. ME.~SURES Questionnaires In addition to the PSS, questionnaires concerning psychosocial stress, coping style, and psychological and physical symptoms were completed. Self-report instruments were chosen on the basis of their theoretical relevance to the stress process and psychometric reliability and validity. The following measures are used in the current analysis: Perceived Stress: The 10-item version ofthe PSS was translated into Dutch by the first author and then back-translated as a check into English by the second author. The items were rated

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Stress and Cortisol ~n a five-point frequency scale, ranging from 0 = "never," to 4 ="very often" in the last month. A total perceived stress score avas obtained by reversing the scoring on the positive items and Then summing across the ten items. All subjects completed the PSS twice, during the initial screening and again immediately preceding Experience Sampling. The two PSS scores were highly .correlated (rho = .73, p c .001); the mean score will be used in the analysis. Psychosomatic Symptoms: The SUNYA Psychosomatic Symptom Checklist(PSC)includes 17 common psychosomatic complaints (e.g. headaches, backaches, and nausea). The scale was originally developed by Cox, Freundlich, and Meyer (42) and revised by Attanasio et al.(43). Subjects rate each complaint on 5-point scales for frequency (0 = "never or rarely occurs;" to 4 = "occurs daily") and intensity(0 = "not bothersome;" to 4="extremely bothersome"). A Total Score,reflecting the overall level of psychosomatic distress, is obtained by summing the cross-products of each item's frequency by intensity. Depression: Depressive symptomatology was assessed with translarion (44) of the Zung Self-Rating Depression Dutch the Scale (45). Anxiety: Trait anxiety was measured with the Dutch version (46) of the State-Trait Anxiety Inventory (STAD. Anger: Trait anger was measured with the Dutch version (47)ofthe Spielberger Trait Anger Scale. Although two subscales exist("anger-temperament" and "anger-reaction"), only the total score is used here. Daily Experience The Experience Sampling Method (35,36,48) was used to collect data from subjects at selected moments during their normal daily activities. Subjects received auditory signals, after which they filled in a questionnaire and collected asaliva sámple. Although additional reports were completed at the end. of each day, for the purpose of this analysis we will refer only to the "beep level" data. After a briefing session, in which all procedures were explained in detail and informed consent was obtained, subjects were sampled for a period of five consecutive days, begnning In early on a Thursday morning and ending late on Mónday. wristSeiko A orkdays. non-w this sample, the weekends were at watch was programmed to emit beeps ten rimes each day, between minutes 90 tely .t semi-random intervals of approxima ~;, ._ the hours of8 a.m. and 10 p.m. Beeps were clustered around 11:15 the midpoint ofeach time block (e.g. 8:15 a.m.,9:45 a.m., varied was beeps of sequence time exact the on); a.m. and so session, éach day to decrease predictability. In afinal debriefing asked were subjects and legibility, for _ESM forms were checked - - to clarify reasons for missing data. Compliance with the procedures was generally -good. The reports criteria we set for inclusion in the analysis (>_20 ESM missno and signalled being after completed within 20 minutes (two subjecu four but all by met were days) entire for ing data avan completed subjecu 88 from each group). The remaining for limit, time the within responses possible all of 83°ró erage of did groups IS and HS àn average of ~41 responses per subject. per subnot differ in compliance rates(40.1 vs. 42.3 responses lowest was ce Complian jest, Mann-Whitney U-test, p > .OS). average an with a.m:), 8:15 tely approxima for the first beep (at for first beeps of73%valid reports. On Saturdays,response rate of all percent our Seventy-f 59°rb. ~:. was 61%, and on Sundays,

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missing and invalid responses on weekends could be attributed to the factthatsubjects veere still asleep. The ESM form contained open-ended questions concerning thought content, the physical and social context, and what the individual was doing when signalled. The forms also included seven-point Likert scales (from 1 = "not at all;" to 7 = "very much"), for rating aspects of thoughts, mood, physical wellbeing, individually defined (psycho)somatic complaints, and present activity. Subjects were asked to describe any stressful events or situations which may have taken place in the interval since the last ESM report and to rate these events on a number of dimensions. Information about smoking (49), food (50), coffee (51), and alcohol intake, medications, and physical exertion (52) since the last beep was also obtained, to help control for possible confounding influences on cortisol secretion. Salivary Cortisol Salivary cortisol is a reliable and valid indicator of the free cortisol in plasma, which is considered to be the biologically active hormone. Cortisol concentrations aze independent ofthe flow rate of saliva (53). Salivary cortisol increases within minutes in response to acute stressons (54) and has ahalf-life of approximately one hour(55). We found no difference in cortisol levels in saliva samples either frozen immediately or kept at room temperature for two days(56); others report no change in unfrozen samples up to 30 days (57). At the same time ESM forms were being completed, subjects collected saliva by holding a cotton dental roll in the mouth for approximately one minute. The saturated roll was placed in a capped plastic vial (Salivette; Sarstedt), which was stored in a specially designed wallet. At the end of each day, subjects placed the vials in their home freezers. At the end of the samplingperiod, uncentrifuged samples were stored at -20 C. Compliance with the saliva sampling procedure »vas good in both high and low. stress.groups, with the same mean response rate (83%) as for the ESM reports. Salivary cortisol levels were determined in duplicate by direct radioimmunoassay (58), using123I-cortisol (Panmos diagnostica, Finland) and antiserum madeagainst the 3-CMO-BSA conjugate by Dr. J. Sulon, University of Liege, Belgium. The lower detection limit of the assay was 12 ng/dl, with a mean intra-assay coefficient of variation of 4.8% (range: 2.2%-7.5% for fow assays). Each subjects samples were analyzed in .the ' same assay to reduce sources of variability. statistical Analysis The 16 ESM mood items were reduced to three mood measures, based on the results of a principal component analysis with varimax rotation, which accounted for 78% of the total variance when subject mean scores were used. Ratings on Zhe items cheerful, satisfied, relaxed,-energetic, self-assured., concentrated, and enthusiastic were summed to form a Posirive AfFect(PA)scale (Cronbaoh'salpha = :95). Two separate components of negative affect (NA) were identified: "NA-]ow arousal," including the items depressed,anxious, worried,lonely, tired, and miserable(alpha =.87),and"NA-high arousal," with the items restless, irritated, hurried, and nervous(alpha = .93). The sums of the scale items were divided -by •the number of items in the scale, so that all mood measures have ranges from 1 to 7. Because the distribution of cortisol values was positively skewed, isansformation to natural logarithms of cortisol con-

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T~+~BLE 1 Differences in Psychological Measures behveen Low and High Sáess Groups Low PSS Mean (st. dev.) Trait measures Perceived Stress (p$S) Trait amciety Trait anger Zung Depression Psychosomatic Symptoms(PSC) ESM measures' pp NA-low arousal NA-high azousal Frequency of stressful events

High PSS Mean (st. dev.)

p-value (2-tailed)

18.1 (3.4) 39.8 (7.6) 23.0(5.2) 48.4(7.7)