Section of General Hospital Psychiatry, Division of Psychological Medicine, Guy's, King's and St Thomas' School of Medicine and Dentistry, London
Section of General Hospital Psychiatry, Division of Psychological Medicine, Guy's, Kings and St Thomas' School of Medicine and Dentistry, and Chronic Fatigue Syndrome Unit, King's College Hospital, London
Section of Neurobiology of Mood Disorders, Division of Psychological Medicine, Institute of Psychiatry, and Affective Disorders Unit, Maudsley Hospital, London
Section of General Hospital Psychiatry, Division of Psychological Medicine, Guy's, King's and St Thomas' School of Medicine and Dentistry, Section of Neurobiology of Mood Disorders, Division of Psychological Medicine, Institute of Psychiatry, Chronic Fatigue Syndrome Unit, King's College Hospital and Affective Disorders Unit, Maudsley Hospital, London
Correspondence: Dr Anthony Cleare, Department of Psychological Medicine, King's College School of Medicine and Dentistry and the Institute of Psychiatry, Weston Education Centre, Cutcombe Road, London SE5 9RJ, UK. Tel: 020 7848 5130; fax: 020 7848 5408; e-mail: a.cleare{at}iop.kcl.ac.uk
Funding detailed in Acknowledgements.
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ABSTRACT |
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Aims To assess the HPA axis using the salivary cortisol response to awakening in CFS.
Method We measured salivary cortisol upon awakening and 10, 20, 30 and 60 min afterwardsin 56 patients with CFS and 35 healthy volunteers.
Results Patients had a lower cortisol response to awakening, measured by the area under the curve.
Conclusions This naturalistic test of the HPA axis response to stress showed impaired HPA axis function in CFS.
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INTRODUCTION |
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METHOD |
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Thirty-five control subjects, recruited from staff, students and volunteers at our institutions, also took part in the salivary cortisol test. Present or past significant medical or psychiatric illness was excluded by a research nurse using a semi-structured interview. Control subjects also were interviewed using the SCAN to exclude major psychiatric illness.
All control subjects and 46/56 patients were free from psychotropic medication, steroids or medication known to affect the HPA axis for a minimum of 2 months prior to endocrine testing. Ten patients were taking medication at the time of testing: nine were taking antidepressants (of whom two were taking additional hypnotics and one was taking sodium valproate) and one was taking pizotifen for migraine. All female subjects were tested during days 17 of their menstrual cycle.
The institutional ethics committee approved all procedures. All patients and controls gave written informed consent.
Questionnaires
Subjects filled out the following questionnaires to assess illness
characteristics: the Chalder Fatigue Scale
(Chalder et al, 1993)
and a global fatigue rating scale
(Vercoulen et al,
1997) for fatigue severity; the Beck Depression Inventory
(Beck et al, 1961) and
General Health Questionnaire12
(Goldberg, 1972) for symptoms
of depression and anxiety; the Symptom Checklist
(Wittenborn & Buhler,
1979) for somatic symptoms; the Medical Outcomes Survey
Short Form 36 (SF36; Jenkinson
et al, 1993) and Work and Social Adjustment Scale
(Marks, 1986) for disability;
and the Pittsburgh Sleep Quality Index
(Buysse et al, 1989)
for sleep disturbance.
Salivary cortisol test
Free cortisol is present in saliva, and salivary cortisol assays have been
shown to be an accurate indicator of total plasma cortisol
(Tunn et al, 1992)
and plasma free cortisol (Kirschbaum &
Hellhammer, 1994). Furthermore, it has been well delineated that
cortisol levels rapidly increase after awakening by around 5060%
(Linkowski et al,
1993; Van Cauter et
al, 1994; Wust et
al, 2000b) and remain elevated for at least 60 min
(Schmidt-Reinwald et al,
1999). Awakening thus acts as a mild stressor and the increase in
cortisol gives an indication of the responsivity of the HPA axis; furthermore,
it has the advantage that salivary testing can be completed in a naturalistic
setting, thus eliminating the confounding stress and anxiety associated with
both intravenous cannulation and hospital attendance. Recent work compared the
results from this test with the more traditional HPA axis tests, such as the
corticotrophin-releasing hormone (CRH) test, adrenocorticotrophic hormone
(ACTH) test and social stress tests, and concluded that it is a useful and
reliable index of the adrenocortical activity, perhaps most closely correlated
with the ACTH test of adrenal reserve
(Schmidt-Reinwald et al,
1999; Wust et al,
2000b). Furthermore, results from the study of over 500
subjects suggest that the response is not significantly affected by age, sleep
duration, time of awakening, use of an alarm clock, smoking or use of an oral
contraceptive, and is stable over time
(Wust et al,
2000b).
All tests were undertaken at home on a normal weekday: subjects who were working were instructed to choose any workday except Monday. Subjects were free to wake up according to their normal schedule because the awakening cortisol profile does not appear to be altered by differences in time of awakening (Pruessner et al, 1997). Subjects were asked to take the first sample while still in bed and then not to have breakfast or brush their teeth during the first hour after awakening in order to avoid falsely high cortisol values due to plasma exudates from minor bleeding in the oral cavity (or from meal-stimulated rises in cortisol). For the 10 min prior to each sample, we asked subjects to remain sitting and not to drink anything, smoke or chew gum. Saliva was collected directly upon waking and then 10, 20, 30 and 60 min after waking. During collection, subjects were instructed not to touch the samples with their hands. At each time point, subjects were asked to write down any difficult or tense conversations or other "hassles" that you have experienced in the last hour. Samples were kept in the refrigerator overnight and sent back in the post in the morning. On arrival at the laboratory they were frozen at -20°C. After thawing, saliva samples were centrifuged at 3000 rev/min for 5 min, which resulted in a clear supernatant of low viscosity. A 50µl aliquot of saliva was used for duplicate analysis. Salivary cortisol was measured using a time-resolved fluoroimmunoassay as described elsewhere (Pariante et al, 2002), except that the rabbit cortisol antibody (product no. 23305105, batch no. 21051565; Biogenesis, Poole, Dorset, UK) and the europium-labelled cortisol were diluted 1:4500 and 1:65, respectively, in assay buffer before use. All samples of one subject were analysed in the same run.
Analysis
Data were checked to confirm normal distribution and parametric statistics
were used. The primary outcome variable was the total cortisol response to
awakening, measured using the integrated area under the curve (AUC). This was
calculated by first subtracting the 0-min awakening value from the 10-, 20-,
30- and 60-min values, to obtain baseline-corrected values, and then using the
trapezoidal method. The AUC was compared between groups using an independent
t-test. Secondary analysis on the main group difference only was
undertaken by carrying out post hoc t-tests at each
baseline-corrected time point. Exploratory analysis was undertaken to see
whether clinical variables were related to the AUC response within the patient
group and to define further the dynamics of the salivary cortisol response in
the group as a whole. Means and standard deviations are given.
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RESULTS |
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Raw data at each time point are shown in Table 2. The cortisol level in the first sample after awakening was similar in both groups, measuring 10.7 nmol/l (s.d.=4.4) in patients and 9.9 nmol/l (s.d.=3.8) in controls (t=0.89, P=0.38). We therefore used this as a baseline on which to calculate the subsequent rise in response to awakening and compared this between the two groups. These responses are shown in Fig. 1. It should be noted that this method of analysis results in the standard deviations appearing artificially high in relation to the adjusted mean values, because the true mean values for the AUC and individual time points are substantially higher, and the adjusted values are often negative. Comparison of the AUC over the 60-min period revealed that patients (mean=70.7 and s.d.=241.6 nmol/l per hour) had lower awakening responses than controls (mean=172.5 and s.d.=240.0 nmol/l per hour), with the t-test result equalling the cut-off for statistical significance (t=1.96, P=0.05; 95% CI 1205). Post hoc t-tests at the individual time points revealed significantly lower cortisol responses in patients than controls 10 min after awakening (cortisol response in patients: mean=0.45 and s.d.=3.9 nmol/l; controls: mean=1.88 and s.d.=2.5 nmol/l; t=2.1, P=0.04; 95% CI 0.12.7) and 60 min after awakening (cortisol response in patients: mean=-0.43 and s.d.=4.8 nmol/l; controls: mean=2.3 and s.d.=4.8 nmol/l; t=2.2; P=0.03; 95% CI 0.45.1).
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Effect of clinical variables
In order to investigate any effect of comorbid psychiatric illness on the
cortisol responses, we split the patients into those without current comorbid
depression (n=34) and those with current comorbid depression
(n=22) according to the SCAN results. The mean AUC in those without
depression (77.3 nmol/l per hour, s.d.=269) did not differ from that in those
with depression (60.5 nmol/l per hour, s.d.=197, t=0.25;
P=0.80).
In order to investigate the possible effect of medication in this sample, we compared the 46 subjects not taking medication with the 10 who were. The mean AUC was 79.4 (s.d.=253) nmol/l per hour in the drug-free group compared with 30.8 (s.d.=181) nmol/l per hour in those on medication, which is a non-significant difference (t=0.57; P=0.57).
There were no correlations between clinical variables and the AUC response, either in all subjects or within patients alone. Neither the body mass index (r=-0.15) nor the awakening time (r=0.02) was significantly correlated to the awakening response. Awakening time did not differ between patients (mean=07.35 h) and controls (mean=07.40 h; t=-0.28; P=0.78). Smokers' awakening responses (mean=101.8 and s.d.= 238.6 nmol/l per hour) did not differ from non-smokers' responses (mean 104.1 and s.d.=252.2 nmol/l per hour; t=0.03; P=0.97). Females (mean=116.8 and s.d.= 210.9 nmol/l per hour) had non-significantly higher responses than males (mean=98.8 and s.d.=294.0 nmol/l per hour; t=0.34; P=0.74).
Dynamics of cortisol response
We found that in 16/91 tests the peak response was reached at 10 min, in
31/91 at 20 min, in 36/91 at 30 min and in 8/91 at 60 min. Using a previously
defined cutoff value for a response to the awakening stress of a
2.5 nmol/l rise above baseline (Wust
et al, 2000b) we found that 61/90 (67%) of
subjects overall showed this response, 25/35 (71%) in the controls and 36/56
(64%) in the patients (difference not significant by 2
test); 4/35 controls (11%) and 12/56 (21%) patients showed a fall in cortisol
values after awaking (difference not significant by
2
test).
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DISCUSSION |
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Comparison with prior studies
Problems with previous studies have included those related to the patient
samples studied. To address some of the problems related to this issue, in
this study we chose to include only subjects meeting the clinical diagnostic
criteria for CFS. We used a gold standard assessment instrument for depression
SCAN in order to assess clearly whether comorbid depressive
illness could influence the results. We chose a group largely free from
medication that might influence the HPA axis.
We are aware of only one prior study (Gaab et al, 2002b) in which the salivary cortisol response to awakening was measured, although on a much smaller group of 21 subjects with CFS. That particular study failed to find any significant difference in morning response in patients and controls. However, the authors did find a supersuppression to dexamethasone, consistent with HPA axis underactivity, perhaps related to enhanced glucocorticoid receptor sensitivity.
Nevertheless, our finding of impaired cortisol response is in keeping with the findings from several studies using CRH and synthetic ACTH, which have also found impaired cortisol response (Cleare, 2003). It is also in keeping with the findings from our group of reduced total 24-h urinary free cortisol output (Cleare et al, 2001). However, there is disagreement between studies and several have failed to find an impaired cortisol response in patients with CFS (Cleare, 2003). Many of these in fact find alterations in ACTH responses to various challenges, including CRH (Demitrack et al, 1991), ACTH (Scott et al, 1998) and insulin-induced hypoglycaemia (Gaab et al, 2002a), a factor that the present design does not allow to be measured.
Comorbid depression
We found that the presence or absence of depression did not materially
alter the finding. This is similar to the finding in our large study of 24-h
urinary free cortisol (Cleare et
al, 2001), where output was reduced regardless of present or
past psychiatric illness. Because the available evidence suggests that the
atypical subtype of depression may be associated also with lowered HPA axis
function, and has fatigue (or leaden paralysis) as a prominent
symptom, the emerging evidence is that the depression seen in CFS is more in
keeping both biologically and phenomenologically with that subtype. We are not
aware of published research investigating the cortisol response to awakening
in depression itself.
Chronic stress
The previous work that has been undertaken using this test has concluded
that chronic social stress (Wust et
al, 2000a) or a high level of perceived stress
(Pruessner et al,
1999) leads to an enhanced awakening response. We did not assess
these variables specifically in this study but our results suggest that
patients with CFS do not share the characteristics of otherwise healthy
individuals under situations of chronic stress. Following on from this, a
further hypothesis might be that subjects with CFS are generally less
responsive to acute naturalistic stressors. However, although Gaab et
al did find a reduced ACTH response to social stress (public speaking)
and exercise stress, the salivary cortisol responses were the same but in a
relatively small sample of 21 (Gaab et
al, 2002a).
Effect of other confounding factors
Ten of our 56 subjects with CFS were taking prescribed medication liable to
affect the HPA axis. Although we did not find a significant difference, the
values were lower and this might have represented a type II error. Indeed, we
have argued previously that medication is likely to be one of the many factors
contributing to HPA axis dysfunction in CFS. It seems most likely that the
observed HPA deficits in CFS are of multi-factorial origin rather than
representing a single change to the HPA axis. Important factors that may be
contributing to HPA axis dysfunction include: disturbed sleep, reduced
physical activity, psychiatric comorbidity; effects of early life experiences
on the HPA such as childhood abuse; medication effects; presence and response
to ongoing psychosocial stressors; and the different influences of these
factors during different illness phases (i.e. acute, sub-acute and chronic
fatigue of varying durations). Heterogeneity of these factors would appear
likely to underlie the inconsistent and divergent findings seen to date.
Despite this, there remain suggestions that HPA dysfunction, and in particular
low circulating cortisol levels, may be one factor contributing to fatigue
chronicity in CFS that is potentially reversible
(Cleare et al,
1999).
Characteristics of salivary cortisol test
Finally, we provide further evidence in this paper regarding the
characteristics of this novel test. First, in our control group we found a
consistent rise of approximately 40% over baseline, similar to previous
reports suggesting a rise of around 50%
(Wust et al,
2000b). Similarly, our finding that around 71% of
controls showed a response to awakening (2.5 nmol/l or more over
baseline, as previously defined) tallies with the figure of 75% reported
previously (Wust et al,
2000b). We also found that smoking, sleep quality and
awakening time do not have a significant effect on the response, in accordance
with the previous literature (Wust et
al, 2000b). A small gender effect has also been
reported in the direction of higher response in females
(Wust et al,
2000b), which is consistent with our findings here. It is
of note that we have sampled somewhat more frequently over the first 30 min of
awakening than prior studies. We found that around half of the tests showed
the peak response before 30 min, suggesting that future studies should include
sampling times before 30 min after awakening.
Limitations
One of the limitations of our study relates to the chosen population, which
was recruited from those referred to a tertiary care centre. We cannot
directly extrapolate these results to those with chronic fatigue seen in the
community, where the HPA axis may be less relevant or less affected. For
example, recent studies of the early stages of development of chronic fatigue
in high-risk samples, such as in the 6 months after EpsteinBarr
infection (Candy et al,
2003) or major surgery (Rubin,
2003), suggest no link between chronic fatigue and the HPA axis.
This has led to the suggestion by some that HPA axis changes occur late in the
course of the illness history in CFS, and may be consequent to the illness
rather than causal (Cleare,
2003).
Another factor to be considered is sample size. Although overall we recruited a relatively large sample of patients compared with previous work in the field, the exploratory analyses looking at the effects of depression and medication use, among other factors, involve sub-groups of the patient sample. Therefore, there is a possibility of type II errors in these analyses.
In conclusion, this study provides further evidence for HPA axis dysfunction in CFS. It advances previous work by undertaking testing in a more naturalistic setting and by using a novel, non-invasive test of the cortisol response to the stress of awakening in a larger sample size than most prior work in the area.
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Clinical Implications and Limitations |
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LIMITATIONS
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ACKNOWLEDGMENTS |
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REFERENCES |
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Beck, A., Ward, C., Mendelson, M., et al (1961) A scale for measuring depression. Archives of General Psychiatry, 4, 561 -571.[Medline]
Buysse, D. J., Reynolds, C. F. D., Monk, T. H., et al (1989) The Pittsburgh Sleep Quality Index: a new instrument for psychiatric practice and research. Psychiatry Research, 28, 193 -213.[CrossRef][Medline]
Candy, B., Chalder, T., Cleare, A. J., et al (2003) Predictors of fatigue following the onset of infectious mononucleosis. Psychological Medicine, 33, 847 -855.[Medline]
Chalder, T., Berelowitz, G., Pawlikowska, T., et al (1993) Development of a fatigue scale. Journal of Psychosomatic Research, 37, 147 -153.[CrossRef][Medline]
Cleare, A. J. (2001) Regulatory disturbances of energy. Advances in Psychosomatic Medicine, 22, 17-34.[Medline]
Cleare, A. J. (2003) The neuroendocrinology of
chronic fatigue syndrome. Endocrine Reviews,
24, 236
-252.
Cleare, A. J., Heap, E., Malhi, G. S., et al (1999) Lowdose hydrocortisone in chronic fatigue syndrome: a randomised crossover trial. Lancet, 353, 455 -458.[CrossRef][Medline]
Cleare, A. J., Blair, D., Chambers, S., et al
(2001) Urinary free cortisol in chronic fatigue syndrome.
American Journal of Psychiatry,
158, 641
-643.
Demitrack, M., Dale, J., Straus, S., et al (1991) Evidence for impaired activation of the hypothalamicpituitaryadrenal axis in patients with chronic fatigue syndrome. Journal of Clinical Endocrinology and Metabolism, 73, 1224 -1234.[Abstract]
Fukuda, K., Straus, S., Hickie, I., et al
(1994) The chronic fatigue syndrome: a comprehensive approach
to its definition and study. Annals of Internal
Medicine, 121, 953
-959.
Gaab, J., Huster, D., Peisen, R., et al
(2002a) Hypothalamuspituitaryadrenal
axis reactivity in chronic fatigue syndrome and health under psychological,
physiological and pharmacological stimulation. Psychosomatic
Medicine, 64, 951
-962.
Gaab, J., Huster, D., Peisen, R., et al
(2002b) The low dose dexamethasone suppression test
in chronic fatigue syndrome and health. Psychosomatic
Medicine, 64, 311
-318.
Goldberg, D. (1972) The Detection of Psychiatric Illness by Questionnaire. London: Oxford University Press.
Jenkinson, C., Coulter, A. & Wright, L. (1993) Short form 36 (SF 36) health survey questionnaire: normative data for adults of working age. BMJ, 306, 1437 -1440.[Medline]
Kirschbaum, C. & Hellhammer, D. H. (1994) Salivary cortisol in psychoneuroendocrine research: recent developments and applications. Psychoneuro-endocrinology, 19, 313 -333.[CrossRef][Medline]
Linkowski, P., Van Onderbergen, A., Kerkhofs, M., et al (1993) Twin study of the 24-h cortisol profile: evidence for genetic control of the human circadian clock. American Journal of Physiology, 264, 173 -181.
Marks, I. (1986) Behavioural Psychotherapy: Maudsley Pocket Book of Clinical Management. Bristol: Wright.
Pariante, C. M., Papadopoulos, A. S., Poon, L., et al (2002) A novel prednisolone suppression test for the hypothalamicpituitaryadrenal axis. Biological Psychiatry, 51, 922 -930.[CrossRef][Medline]
Pruessner, J. C., Wolf, O. T., Hellhammer, D. H., et al (1997) Free cortisol levels after awakening: a reliable biological marker for the assessment of adrenocortical activity. Life Sciences, 61, 2539 -2549.[CrossRef][Medline]
Pruessner, J. C., Hellhammer, D. H. & Kirschbaum, C.
(1999) Burnout, perceived stress, and cortisol responses to
awakening. Psychosomatic Medicine,
61, 197
-204.
Rubin, G. J. (2003) The Causes and Maintenance of Postoperative Fatigue. London: Institute of Psychiatry.
Schmidt-Reinwald, A., Pruessner, J. C., Hellhammer, D. H., et al (1999) The cortisol response to awakening in relation to different challenge tests and a 12-hour cortisol rhythm. Life Sciences, 64, 1653 -1660.[CrossRef][Medline]
Scott, L.V., Medbak, S. & Dinan, T. G. (1998) The low dose adrenocorticotropin test in chronic fatigue syndrome and in health. Clinical Endocrinology, 48, 733 -737.[CrossRef][Medline]
Sharpe, M., Archard, L., Banatvala, J., et al (1991) Chronic fatigue syndrome: guidelines for research. Journal of the Royal Society of Medicine, 84, 118 -121.[Medline]
Sharpe, M., Chalder, T., Palmer, I., et al (1997) Chronic fatigue syndrome. A practical guide to assessment and management. General Hospital Psychiatry, 19, 185 -199.[CrossRef][Medline]
Tunn, S., Mollmann, H., Barth, J., et al
(1992) Simultaneous measurement of cortisol in serum and
saliva after different forms of cortisol administration. Clinical
Chemistry, 38, 1491
-1494.
Van Cauter, E.V., Polonsky, K. S., Blackman, J. D., et al (1994) Abnormal temporal patterns of glucose tolerance in obesity relationship to sleep-related growth hormone secretion and circadian cortisol rhythmicity. Journal of Clinical Endocrinology and Metabolism, 79, 1797 -1805.[Abstract]
Vercoulen, J. H., Bazelmans, E., Swanink, C. M., et al (1997) Physical activity in chronic fatigue syndrome: assessment and its role in fatigue. Journal of Psychiatric Research, 31, 661 -673.[CrossRef][Medline]
Wessely, S., Hotopf, M. & Sharpe, M. (1998) Chronic Fatigue and its Syndromes. Oxford: Oxford University Press.
Wittenborn, J. & Buhler, R. (1979) Somatic discomforts among depressed women. Archives of General Psychiatry, 36, 465 -471.[Abstract]
Wolfe, F., Smythe, H., Yunus, M., et al (1990) The American College of Rheumatology 1990 criteria for the classification of fibromyalgia: report of the multicenter criteria committee. Arthritis and Rheumatism, 33, 160 -173.[Medline]
World Health Organization (1994) Schedules for Clinical Assessment in Neuropsychiatry, version 2.0. Manual. Geneva: WHO.
Wust, S., Federenko, I., Hellhammer, D. H., et al (2000a) Genetic factors, perceived chronic stress, and the free cortisol response to awakening. Psychoneuroendocrinology, 25, 707 -720.[CrossRef][Medline]
Wust, S., Wolf, J., Hellhammer, D. H., et al (2000b) The cortisol awakening response normal values and confounds. Noise and Health, 7, 77-85.
Received for publication February 28, 2003. Revision received July 31, 2003. Accepted for publication September 8, 2003.
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