BMJ Open-2012-Sjörs-

Long-term follow-up of cortisolawakening response in patients treatedfor stress-related exhaustion

Anna Sjors,1,2 Thomas Ljung,3,4 Ingibjorg H Jonsdottir1,5

ABSTRACTObjectives: Studies on hypothalamusepituitaryeadrenal (HPA) axis activity in stress-related exhaustionand burnout have revealed incongruent results, andfew longitudinal studies on clinical populations havebeen performed. This study was designed toinvestigate differences in HPA axis activity betweenpatients with stress-related exhaustion and healthycontrols and to investigate longitudinal changes in HPAaxis activity in the patient group as they entereda multimodal treatment programme.

Design: HPA axis activity was assessed through thecortisol awakening response (CAR). Salivary cortisolwas sampled at awakening and after 15 min. Follow-upmeasurements were performed in the patient groupafter 3, 6, 12 and 18 months.

Setting: An outpatient clinic specialising in stress-related illness.

Participants: Patients with clinically diagnosed stress-related exhaustion (n¼162) and healthy controls(n¼79).

Primary and secondary outcomemeasures: The primary measure was CAR measuredas the difference between the two salivary cortisolsamples. Changes in CAR during follow-up wererelated to changes in symptoms of burnout,depression and anxiety.

Results: Patients showed similar CAR as the controlsand their CAR did not change significantly duringtreatment. No association was found between CAR andsymptom development during treatment.

Conclusions: The authors conclude that CAR doesnot seem to discriminate clinically defined patientswith exhaustion from healthy controls and it appearsnot to change during treatment. CAR, measured assalivary cortisol, at awakening and after 15 min, isthus not a valid marker for stress-relatedexhaustion.

INTRODUCTIONStress-related illness is a major problem inmany countries1 and presents unique chal-lenges to persons with health problems andfor their healthcare providers. Particularly,

the lack of characteristic clinical signs ordiagnostic laboratory abnormalities increasesdifficulty in assigning a correct diagnosis ortreatment. Several partly overlappingconcepts, such as burnout, exhaustiondisorder (ED), vital exhaustion and chronicfatigue syndrome (CFS), are used in theliterature to describe patients with stress-related exhaustion.The burnout concept is widely used and

internationally recognised as one of severalmental health outcomes of chronic stress.2

Emotional exhaustion has been put forwardas the core element of the burnoutsyndrome.2 3 However, burnout syndrome isnot a clinically defined illness, and a bettermore selective conceptualisation of stress-related pathologies is needed. Diagnosticcriteria for the medical condition referred toas ED was formulated by the National Boardof Health and Welfare in Sweden4 to definea more homogenous clinical populationregarding the severity of the mental health

To cite: Sjors A, Ljung T,Jonsdottir IH. Long-termfollow-up of cortisolawakening response inpatients treated forstress-related exhaustion.BMJ Open 2012;2:e001091.doi:10.1136/bmjopen-2012-001091

< Prepublication history forthis paper is available online.To view these files pleasevisit the journal online (http://dx.doi.org/10.1136/bmjopen-2012-001091).

Received 29 February 2012Accepted 18 June 2012

This final article is availablefor use under the terms ofthe Creative CommonsAttribution Non-Commercial2.0 Licence; seehttp://bmjopen.bmj.com

1The Institute of StressMedicine, Gothenburg,Sweden2Rehabilitation Medicine,Department of Medical andHealth Sciences, LinkopingUniversity, Linkoping,Sweden3County Council of Jamtland,R&D-unit, Ostersund,Sweden4Mid Sweden University, IHV,Ostersund, Sweden5Institute of Neuroscienceand Physiology, TheSahlgrenska Academy,University of Gothenburg,Gothenburg, Sweden

Correspondence toDr Anna Sjors;[email protected]

ARTICLE SUMMARY

Article focus- HPA axis activity measured through CAR in

patients with stress-related exhaustion.- Follow-up assessments of CAR were performed in

the patient group during 18 months of treatment.

Key messages- In this study, CAR did not discriminate patients

with exhaustion from healthy controls and CARdid not change during treatment.

- Thus, CAR, measured as salivary cortisol, atawakening and after 15 min, does not seem to bea valid marker for stress-related exhaustion.

Strengths and limitations of this study- Two major advantages were the longitudinal

design with four follow-up assessments and therelatively large sample of patients included in thestudy.

- A limitation was the single day cortisol samplingat each follow-up assessment and using only twosamples per day.

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problem and its relation to stress exposure. This studyinvestigates a population of ED patients, but uses theburnout concept in parallel, to facilitate comparisons torelated literature. ED and self-reported burnout overlap88%e92%, as previously reported.5

It has been hypothesised that the hypothalamusepituitaryeadrenal (HPA) axis is involved in the patho-genesis of stress-related illness since it is the centralneuroendocrine system involved in long-term adaptationto stress.6 7 According to Raison and Miller,8 a disturbedHPA axis could cause the array of symptoms observed inindividuals with stress-related disorders. Most researchon associations between stress, HPA axis activity andphysical and emotional well-being in humans has reliedon correlational data. Much of this research is also cross-sectional, showing point-in-time rather than longitudinalassociations.Salivary cortisol awakening response (CAR) is

a common method used to assess HPA axis activity. Ina recent meta-analysis, Chida and Steptoe9 concludedthat CAR was negatively related to fatigue, burnout orexhaustion. However, studies on HPA axis regulationspecifically in burnout subjects have revealed incon-gruent results.10 In strongly affected individuals on sickleave or with a clinical diagnosis, both elevated11 12 andnon-elevated13e15 awakening cortisol levels, comparedwith healthy control subjects, have been reported.Studies including subjects still at work but scoring highon burnout also show contradictory results, rangingfrom signs of a hypoactive HPA axis16 17 to normal HPAaxis18 or hyperactive axis.19 20

These inconsistencies could possibly be explained bythe heterogeneity in burnout populations, partly due todifferences in diagnostic criteria or use of differentburnout scales. Using the term ‘burnout’ in both clini-cally diagnosed patients and working populationsscoring high on burnout questionnaires makes compar-ison of results in the literature difficult. Burnout in itselfis a process suggested to develop over longer periods oftime, implying that the HPA axis may not function thesame in persons experiencing early stages of burnout asin persons suffering from more severe and chronicforms of burnout.21 Furthermore, relatively smallsamples have been investigated, especially in studies ofclinically diagnosed patients with more severe symptoms,thereby increasing the risk of chance findings in indi-vidual studies.Longitudinal studies of HPA axis activity in stress-

related exhaustion or burnout are scarce. Moch et al22

reported no difference in serum cortisol at baseline butlower levels after 4 months following a stress managementintervention in 16 female burnout patients comparedwith matched controls. Urinary free cortisol levels wereconsistently lower in the patient group throughout the4 months. Mommersteeg et al23 measured salivary cortisolin a group of 74 burnout patients before and after treat-ment and again at follow-up approximately 6 monthslater. They found no changes in salivary cortisol over time

but some indications of a relationship between individualchanges in cortisol and changes in burnout symptoms.Thus, it is still unclear whether HPA axis activity changesduring the development of and recovery from exhaus-tion/burnout and whether there is any association withsymptom development.The study was designed to investigate CAR in a rela-

tively large sample of patients with clinically diagnosedstress-related exhaustion compared with healthycontrols and to investigate the longitudinal develop-ment of CAR during treatment in the patient group.Furthermore, we intended to elucidate potentialdifferences between subgroups of patients based ondepression diagnosis, antidepressant use and symptomduration and investigate whether CAR is associated withthe development of different symptoms during treat-ment. Since previous studies have shown contradictoryresults regarding HPA axis function and burnout/exhaustion, we considered our study as mainly explor-atory. However, given the large sample of patients withsuch pronounced clinical exhaustion, we hypothesisedthat a somewhat more hypoactive HPA axis with lowerawakening cortisol levels followed by flatter responseafter awakening would be seen in the patientscompared with controls.

MATERIALS AND METHODSParticipantsThis study included 162 patients with stress-relatedexhaustion referred to an outpatient clinic at the Insti-tute of Stress Medicine located in Gothenburg, Sweden.In addition, 85 participants were recruited to serve ashealthy controls from an ongoing longitudinal cohortstudy in the Vastra Gotaland Region (mainly healthcareworkers and social insurance officers) and from adver-tisements in daily newspapers. The study was approvedby the Regional Ethical Review Board in Gothenburg,Sweden, and was conducted in accordance with theDeclaration of Helsinki. All participants included in thestudy gave written informed consent.The inclusion criteria for patients were (1) clinically

diagnosed ED, as defined in box 1 and (2) a maximumduration of sick leave of 6 months. The inclusion criteriafor controls were age of 25e50 years and body massindex (BMI) 18.5e30 kg/m2. None of the controlsfulfilled diagnostic criteria for ED.The exclusion criteria for both patients and healthy

controls were as follows: systemic disease (such as thyroiddisorder, hypertension or diabetes), psychiatric disease(except for depression, anxiety and exhaustion for thepatients), present infection, pregnancy, breastfeeding,medication with substances having systemic effects (exceptfor antidepressants for the patients), vitamin B12 defi-ciency and over-consumption of alcohol. This was ensuredpartly by asking participants of known diseases, partly bymeasuring blood pressure and performing electrocardio-graphic registration. Blood samples were also taken andblood sedimentation rate and levels of glucose,

2 Sjors A, Ljung T, Jonsdottir IH. BMJ Open 2012;2:e001091. doi:10.1136/bmjopen-2012-001091

Longitudinal CAR in stress-related exhaustion




haemoglobin, HbA1c, free T4 and thyroid-stimulatinghormone were measured. Psychiatric symptoms wereassessed using the Comprehensive PsychopathologicalRating Scale and the Hospital Anxiety and Depression(HAD) scale. Vitamin B12 deficiency was assessed bymeasuring homocysteine, and over-consumption ofalcohol was measured with the Alcohol Use DisordersIdentification Test. Participant characteristics are shown intable 1.

Further description of the ED patientsThe patients were ambulatory at the time of study, andnone had received inpatient care due to their illness.They were referred from primary care or occupationalhealthcare centres between 2004 and 2008. Comorbidityof depression and/or anxiety was screened for using theone-page Primary Care Evaluation of Mental Disordersquestionnaire,24 followed by a structured physicianinterview using a form based on the DSM IV criteria fordiagnostic assessment of mood and anxiety disorders.Patients received individually adapted multimodaltreatment and follow-up during 18 months at the clinicas described by Glise et al.25 Treatment commonlyincluded advice and discussions of lifestyle and physical

activity, stress reduction programmes and/or psycho-logical treatment. Antidepressant medication wasoffered or adjusted when needed.A total of 274 patients (184 women and 90 men)

entered the treatment and follow-up programme at theclinic and among those, 162 patients (103 women and59 men) provided complete salivary cortisol data from allfollow-up assessments and were thus selected for analysis.These 162 patients were significantly older than the 112excluded patients (mean age for the included patientswas 44 years (SD 9) and for the excluded patients was40 years (SD 9), t¼3.9, p<0.001) and had lower burnoutscores (median for included patients was 5.3 and medianfor excluded patients was 5.6, Z¼2.0, p¼0.048). They didnot differ significantly regarding BMI or symptoms ofdepression and anxiety.Of the patients selected for analyses, 61% were diag-

nosed with both depression and anxiety, 16% fulfilledrequirements for depression only and 15% for only ananxiety disorder. The self-reported duration of symp-toms before seeking medical help was more than 5 yearsfor 11% of the patients, 3e5 years for 19%, 1e2 yearsfor 29% and <1 year for 42%. Eighty-five per cent ofthe patients reported some degree of sick leave atinclusion.

Box 1 Diagnostic criteria for exhaustion disorder asproposed by the Swedish National Board of Health andWelfare

Diagnostic criteria for exhaustion disorderA. Physical and mental symptoms of exhaustion with

minimum 2 weeks duration. The symptoms have devel-oped in response to one or more identifiable stressorsthat have been present for at least 6 months.

B. Markedly reduced mental energy, which is manifestedby reduced initiative, lack of endurance or increasedtime needed for recovery after mental efforts.

C. At least four of the following symptoms have beenpresent most of the day, nearly every day, during thesame 2-week period:1. Persistent complaints of impaired memory.2. Markedly reduced capacity to tolerate demands or to

work under time pressure.3. Emotional instability or irritability.4. Insomnia or hypersomnia.5. Persistent complaints of physical weakness or fatigue.6. Physical symptoms such as muscular pain, chest

pain, palpitations, gastrointestinal problems, vertigo orincreased sensitivity to sounds.

A. The symptoms cause clinically significant distress orimpairment in social, occupational or other importantareas of functioning.

B. The symptoms are not due to the direct physiologicaleffects of a substance (such as a drug of abuse ora medication) or a general medical condition (eghypothyroidism, diabetes, infectious disease).

C. If criteria for major depressive disorder, dysthymicdisorder or generalised anxiety disorder are met,exhaustion disorder is set as a comorbid condition.

Table 1 Descriptive data of patients and healthy controls

Patients(n[162)

Controls(n[85)

Testvalue p Value

Age, mean(SD) in years

44 (9) 45 (9) t¼0.5 0.595

Sex (% male) 36% 51% c2¼4.6 0.032BMI, mean(SD) in kg/m2

24.3 (3.0) 23.5 (2.4) t¼�2.2 0.031

WHR,mean (SD)

0.87 (0.1) 0.87 (0.1) t¼1.0 0.324

Antidepressantuse

27% N/A

Depressiondiagnosis

77% N/A

Anxietydiagnosis

75% N/A

Burnoutscore (SMBQ)

c2¼165.8 <0.001

<4 8% 93%$4 92% 7%

HADdepressionscore

c2¼95.9 <0.001

0e6 27% 94%7e10 43% 6%>10 30% 0%

HAD anxietyscore

c2¼137.5 <0.001

0e6 9% 84%7e10 31% 10%>10 60% 6%

BMI, body mass index; WHR, waist-hip ratio; SMBQ, Shirom-Melamed Burnout Questionnaire; HAD, Hospital Anxiety andDepression Scale.






CORTISOL MEASUREMENT PROTOCOLTo assess individual cortisol response to awakening,saliva samples were collected at home using Salivettetubes (Sarstedt, Numbrecht, Germany) immediatelyafter waking up and 15 min later. The participants werefree to choose a typical weekday for saliva collection, andthey were instructed not to brush their teeth, eat ordrink anything 30 min before taking a sample. Thisinstruction was given verbally as well as through detailedwritten information accompanying the sampling tubes.Collection time was recorded in a paper diary. Femaleparticipants were instructed to perform the salivacollection on one day between day 5 and 10 in themenstrual cycle (ie, the follicular phase) sincethe diurnal cortisol profile could be influenced by themenstrual cycle.26 The same procedure was repeatedafter 3, 6, 12 and 18 months in the patient group.Salivette tubes were kept refrigerated after collection

at home until they were returned to the clinic. Thesamples were delivered at the next visit, if scheduledwithin 1 week from sampling or sent by mail. Sampleswere then stored at �208C until they were assayed. Freecortisol levels in saliva were analysed by the Laboratoryfor Clinical Chemistry, Sahlgrenska University Hospital,using a competitive radioimmunoassay (Spectria CoatedTube Radioimmunoassay; Orion Diagnostica, Espoo,Finland). The limit of detection was 1 nmol/l, and theinterassay coefficient of variance was below 14%.

QUESTIONNAIRESSelf-reported burnout was evaluated in this study usingthe Shirom-Melamed Burnout Questionnaire (SMBQ).The questionnaire includes 22 items measuring differentaspects of the burnout syndrome, including physicalfatigue, emotional exhaustion, tension, listlessness andcognitive weariness as defined by Melamed andcoworkers.27 The SMBQ correlates strongly with theMaslach Burnout Inventory, another widely used instru-ment for measurement of burnout.3 Stenlund andcoworkers28 reported the mean total score in patientswith burnout as 5.7 for women and 5.6 for men. Instudies of white-collar workers, scores of $3.75 on theSMBQ were used to classify workers with high burnout,and in another study, the median split $4 was used asthe level for burnout.3 12 Relating to these previousstudies, a score of $4.0 on the SMBQ was chosen as thecut-off for burnout in the present study.The HAD scale was used to assess self-reported

depression and anxiety in both patients and controls. Itwas originally developed for non-psychiatric clinics tomeasure symptoms of depression (HAD-D) and anxiety(HAD-A),29 and the scale has been found to performwell in assessing anxiety disorders and depression indifferent patient groups as well as in the general popu-lation.30 Scores 0e6 indicate non-cases, 7e10 indicatepossible cases and scores above 10 on each respectivesubscale indicate probable cases.

STATISTICAL ANALYSESAll statistical analyses were conducted in SPSS V.19.0.A p value of <0.05 was considered statistically significant.Student’s t tests and c2 tests were used to comparedemographics and questionnaire scores betweenpatients and controls. Cortisol data were analysed withrepeated measures analysis of variance (ANOVA).Correction of degrees of freedom according to theGreenhouse-Geisser procedure (3) was performedwhenever sphericity was violated. Since cortisol data wereskewed, all cortisol measurements were ln-transformedbefore these analyses. Effect sizes were calculated forsignificant results by partial eta squared (h2), expressingthe amount of variance explained in the dependentvariable by the respective effect.

CAR in patients and healthy controlsSalivary cortisol after awakening was analysed usingrepeated measures ANOVA with sample (awakening andafter 15 min) as the within-subjects factor and group(patient or control) as the between-subjects factor. Thepotential confounders age, sex, BMI, waist-hip ratio(WHR), HAD-D and HAD-A were included as covariatesin the repeated measures ANOVAs to investigate possibleeffects on awakening cortisol.

CAR in subgroups of patientsThe difference between the second and first morningsample (15 min after awakeningdawakening) was usedas a simple measurement of CAR. Relative CAR (relCAR)was computed as CAR/awakening 3100. t Tests wereperformed to investigate differences in CAR and relCARbetween patients scoring $4 or <4 on the SMBQ andpatients with or without depression diagnosis and anti-depressant use at inclusion. Moreover, possible differ-ences in CAR and relCAR depending on the level ofanxiety and depressive symptoms at inclusion (HAD <7,HAD 7e10 or HAD >10) were analysed in the patientgroup by means of one-way ANOVA.

Longitudinal development of CARLongitudinal development was analysed usinga repeated measures ANOVA that analysed CAR over thecourse of treatment. Time (inclusion, 3 months,6 months, 12 months and 18 months) was applied as therepeated factor, and possible differences betweendifferent subgroups of patients were analysed byapplying group as a fixed factor and time 3 group as aninteraction effect. Groupings were made according todepression diagnosis at inclusion (yes or no), antide-pressant use (at inclusion, introduced during treatmentor no use) and symptom duration before inclusion inthe study (more than 5 years, 3e5 years, 1e2 years or<1 year), respectively. Age, sex, nicotine use (current,previous or no use), exercise habits (sedentary, light,moderate or vigorous physical activity), BMI and WHRwere applied as covariates.






Associations between CAR and symptom developmentPossible relationships between CAR and symptomdevelopment during treatment were analysed bySpearman rank correlations (r) between changes inCAR from inclusion to follow-up at 3, 6, 12 and18 months and changes in burnout, depressive andanxiety symptoms over the same time intervals.

RESULTSCAR in patients and healthy controlsAs burnout and exhaustion are considered closelyrelated, controls with a burnout score $4 (n¼6) wereexcluded from all analyses. Both patients and controlsshowed a significant rise in cortisol after awakening(main effect of sample, F(1, 238) ¼ 174.2, p<0.001,h2¼0.423; see figure 1). There was, however, no differ-ence in cortisol level between the patient group and thecontrol group (main effect of group, F(1, 238) ¼ 0.05,p¼0.829) or rise in cortisol after awakening (sample 3group interaction effect, F(1, 238) ¼ 0.3, p¼0.615).Twenty-one patients (13%) and 15 controls (19%) hada negative CAR and excluding these participants did notalter the result. No effect of age, sex, BMI, WHR, HAD-Dor HAD-A could be found as they were entered ascovariates, either separately or together.

CAR in subgroups of patientsAs seen in figure 2, patients using antidepressants hada slightly smaller rise after awakening, although thisdifference was not statistically significant in the t tests ofCAR (t¼1.1, p¼0.268) and relCAR (t¼�0.2, p¼0.866).There were no significant differences in CAR or

relCAR between patients with or without depressiondiagnosis at inclusion or between subgroups of patientswith various levels of symptoms of burnout, anxiety ordepression at inclusion (data not shown).

Longitudinal development of CARRepeated measures ANOVA indicated that CAR didnot change significantly over the course of treatment

(F(4, 644) ¼ 2.0, p¼0.108, 3¼0.838, figure 3). Possibleimpact of antidepressants on CAR in this patient groupwas investigated further by group division according toantidepressant use. This analysis gave no significant maineffect of group (F(2, 157)¼1.4, p¼0.260) and no signifi-cant time 3 group interaction effect (F(8, 628)¼1.2p¼0.304, 3¼0.836), indicating that antidepressant use didnot affect CAR during treatment. Likewise, group divisionaccording to depression diagnosis at inclusion revealedno significant group (F(1, 160)¼0.1, p¼0.778) or inter-action effect (F(4, 640)¼0.8, p¼0.501, 3¼0.838). Therewere no significant differences between patients reportingdifferent durations of symptoms before inclusion (groupeffect, F(3, 154)¼0.8, p¼0.503 and time3 group effect, F(12, 616) ¼ 0.8, p¼0.614, 3¼0.802). Introducing cova-riates in the analyses did not change these results.

Associations between CAR and symptom developmentThe percentage of patients with burnout (SMBQ $4)decreased from 92% at inclusion to 64% at the 3-month

Figure 1 Mean salivary cortisol (6SEM) after awakening inpatients with stress-related exhaustion and in healthy controls.

Figure 2 The impact of antidepressant use on mean salivarycortisol (6SEM) after awakening in patients with stress-relatedexhaustion.

Figure 3 Mean cortisol awakening response (6SEM) atinclusion and during the 18-month treatment programme.






follow-up, 51% at 6 months, 41% at 12 months and,finally, 33% at the 18-month follow-up. HAD-A scores>10 was seen in 60% of the patients at inclusion, 30% at3 months, 20% at 6 months, 13% at 12 months and 9%at 18 months. The percentage of patients scoring HAD-D>10 decreased from 30% at inclusion to 12% at3 months, 11% at 6 months, 8% at 12 months and 6% at18 months. Further details regarding symptom develop-ment and clinical improvement during treatment havebeen presented elsewhere.25 No significant correlationswere found between symptom development (SMBQ,HAD-D and HAD-A) during treatment and changes inCAR over the course of treatment (absoluter¼0.003e0.14, p values ¼ 0.971e0.097).

DISCUSSIONThe main findings in the present study were thatpatients with ED showed similar CAR to controls andthat CAR did not change significantly during treatment.

CAR in patients and healthy controlsWe confirm several previously published studies, showingno significant differences in awakening cortisol leveland/or rise thereof between clinical populations ofburnout subjects and controls13e15 but, as previouslymentioned, contrasting results have been reported.11 12 31

Thus, clinically diagnosed stress-related exhaustion doesnot seem to be related to changes in HPA axis activity, atleast not to the CAR, as measured in this study.A commonly suggested explanation for the heteroge-

neity in the literature concerning HPA axis in burnout isthat HPA axis functioning changes as the burnoutsyndrome develops from enhanced work stress overheightened burnout scores to severe burnout or evenclinical diagnosis of burnout.10 14 20 It has been hypoth-esised that the earlier stages of burnout are characterisedby increased levels of free cortisol, while the later stages areassociated with lower than normal cortisol levels, repre-senting a breakdown of endocrine feedback mecha-nisms.32 33 If thesewere the case,wewouldprobably expectthat clinically defined patients with exhaustion and highburnout scores would show altered CAR when comparedwith a control group. However, this was not found.

CAR in subgroups of patientsOne possible explanation for the discrepancy betweendifferent studies, regarding HPA axis function, could bethe presence of comorbidities. The clinical symptoms ofother stress-related pathologies such as depression, post-traumatic stress disorder (PTSD), fibromyalgia and CFSpartly overlap with symptoms seen in patients withburnout and exhaustion. These disorders showcontrasting HPA axis disturbances,34 with higher cortisollevels as a characteristic of major depression,35 36 whereasPTSD, fibromyalgia and CFS are associated with hypo-function of the HPA axis.35e38 Thus, differences betweencases and controls may, to a larger extent, actually beattributed to these comorbidities rather than solely to the

presence of exhaustion and/or burnout. In this particularstudy, no patients with PTSD, CFS or fibromyalgia wereincluded, but comorbid depression was present in themajority of the patients. The analysis with groupings ofpatients according to depression did not, however, revealany differences in awakening cortisol between those whodid and did not fulfil the diagnostic criteria for depres-sion, indicating that comorbid depression does notcontribute significantly in explaining the lack of differ-ence between ED patients and controls.A recent meta-analysis concluded that the relationship

between HPA axis activity and depression is not asstraightforward as often suggested.39 HPA axis hypo-activity has been related to atypical depression, which isalso characterised by profound fatigue and inertia,whereas hypercortisolism is frequently observed inmelancholic depression.40 A previous study of job stress-induced depression, with a population similar to thepresent ED population, showed a marked decrease ofHPA axis reactivity to dexamethasone/corticotropin-releasing hormone challenge, which is opposite to whathas been described in major depression.41 The lack ofassociation between CAR and depressive symptoms, asobserved in the present patient group and in theprevious studies,14 20 31 further complicates the picture.Impairments of psychological well-being are not neces-sarily related to easily detectable dysregulations of theHPA axis, and subjective stress reactions are not alwaysreflected in cortisol responses.21

Longitudinal development of CARWe found no significant changes in CAR over time inpatients with ED despite clinical and psychologicalimprovement during treatment. Similar results havebeen reported previously,22 23 although a pilot study of22 burnout patients reported increased awakeningcortisol after psychotherapy.31 Moch et al22 suggestedthat the clinical improvement and reduction of symp-toms may precede any accompanying change inbiochemical markers. However, since our patient groupdid not differ from healthy controls at the time ofinclusion, changes in CAR in any particular directioncould perhaps not be expected.Moreover, the lack of association between CAR and self-

reported symptom duration before inclusion was some-what puzzling, given the hypothesis above, and it alsopoints in the direction that basal salivary cortisol is nota sensitive biological marker for exhaustion/burnout. Wecannot, however, rule out that cortisol measured at othertime points during the day, as in the evening, could beaffected in this patient group, but the data on CAR doesnot implicate any substantial pathological change in thebasal non-stimulated HPA activity. Further studies,measuring cortisol during other time points, might revealwhether the cortisol level is affected in this patient group.

Methodological considerationsIrrespective of the body of literature reporting no cortisoldeviation in exhaustion/burnout populations,42 there still






seems to be a strong belief that HPA axis dysregulation isa key aspect in the pathogenesis of stress-related illness.Our results do not rule out the possibility of a dysfunc-tional HPA axis in ED in terms of altered stress reactivity oraltered feedback inhibition. Impaired habituation torepeated stress exposures or increased or decreasedresponses to acute stress are potential pathways by whichstress-related illness may be linked to HPA axis dysfunc-tion. Speculatively, any deviations in HPA axis activitycould emerge when the stress system is challenged, as bya psychosocial stressor such as the Trier Social Stress Testor by dexamethasone suppression tests. Moreover, it ispossible that a combination of several biomarkers,including HPA axis parameters, would be more sensitive indiscriminating between ED or burnout cases and controlsand thereby serve better as marker for stress-related illness.Cortisol sampling points at awakening and 15 min

later were chosen to ensure that salivary cortisol wouldbe firmly on the upward slope of the morning cortisolresponse.43 Moreover, memory deficits and cognitiveimpairments are a common feature in ED,41 44 anda shorter time span between sampling points was there-fore desirable to facilitate remembering to perform thenext sample, which would thereby increase compliancewith sampling instructions. Collecting only two sampleswas, however, a limitation to the study since three ormore samples are recommended to fully cover theawakening response.9 Resources for the current studydid not allow a more extensive cortisol samplingprotocol, given the extensive follow-up measurements.The patient group included in the analyses differs

somewhat compared with the patients who did not havecomplete samples of saliva during the follow-up.However, CAR at the time of inclusion did not differbetween the 162 patients included in the study and the112 excluded due to incomplete follow-up assessments(t ¼�0.2, p¼0.808). Hence, we do not think that suchdifferences, including burnout level, were important.To obtain a homogenous population of patients

regarding stress-related exhaustion, we ensured that allpatients fulfilled the diagnostic criteria for ED. Moststudies on stress-related illness have instead used theconcept of burnout. However, burnout is a psychologicalterm with different definitions depending on theinstrument used and with no clearly defined diagnosticcriteria. Moreover, burnout has its focus on work stressand does not consider that stress-related illness can bedue to stressors outside the workplace. Therefore,instead of using the burnout concept, we chose to onlyinclude patients with ED. Care was taken to ensure thatno other somatic or psychiatric illness could explain thecondition and special attention was given to excludepatients with fibromyalgia and CFS, since there isa considerable overlap between these conditions andED. Patients with comorbid depression and/or anxietywere, however, not excluded from the study. Comorbiddepression and anxiety is common in the patient groupincluded in this study, and we thus confirm the previous

literature that coexistence of depression, anxiety andburnout/exhaustion is often seen in patients reportingstress-related mental health problems.13 45e47 In a recentpaper, published by our group,25 the course of symptomsfor depression, anxiety and burnout was followed over18 months, showing that symptoms indicating probabledepression or anxiety declined more rapidly thansymptoms of burnout. Thus, the core symptoms of thesepatients seem to be burnout, including physical andmental exhaustion, rather than depression and anxiety,but the overlap of these symptoms needs to be furtherstudied. Some patients were on antidepressants, whichpotentially could influence HPA axis activity. However,the subgroup analyses in the patient group did not showany significant effects from antidepressant use.The majority of the patients referred to the clinic

report relatively high socioeconomic status, includinghigh educational level, with few reporting unemploy-ment. This should be acknowledged as a selection biascompared with the general population of patients withstress-related problems. Furthermore, patients seekingcare for stress-related problems often report severalother symptoms including musculoskeletal pain. Thegroup of patients studied here differs somewhat fromthe general patient population in primary care mainlybecause patients with chronic pain problems areexcluded since we are interested in studying patientsprimarily reporting stress-related exhaustion andburnout. The previous research on similar patientgroups, showing changes in cortisol levels, could thushave been performed on different patient groups, suchas those reporting more chronic pain problems.

CONCLUSIONSCAR, as measured in the present study, does not seem todiscriminate patients with clinically defined stress-relatedexhaustion from healthy controls, and CAR also appearsnot to change over the course of treatment. Thus,morning cortisol measurements in saliva do not seem tobe a valid biological marker for exhaustion. The resultsdo not refute a role for other aspects of the HPA axis inthe long-term effects of stress since a limited measure ofthe HPA axis function was included in this study.

Acknowledgements We gratefully acknowledge Karin Nygren and Marie-Louise Norberg for their valuable help in salivary cortisol analyses.

Contributors AS analyzed and interpreted the data and drafted the article, TLand IHJ contributed to conception and design of the study, interpretation ofthe data and revised the article for critical intellectual content. All authorsapproved the final version of the article.

Funding This research received no specific grant from any funding agency inthe public, commercial or not-for-profit sectors.

Competing interests None.

Ethics approval The Regional Ethical Review Board in Gothenburg.

Provenance and peer review Not commissioned; externally peer reviewed.

Data sharing statement No additional unpublished data from the study areavailable.






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Anna Sjörs, Thomas Ljung and Ingibjörg H Jonsdottir stress-related exhaustionresponse in patients treated for Long-term follow-up of cortisol awakening

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