Testing the ecological validity of the Trier Social Stress Test : Association with real-life exam stress

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Testing the ecological validity of the Trier Social Stress Test:

Association with real-life exam stress

Gina-Isabelle Henze

^a

, Sandra Zänkert

^a

, David F. Urschler

^a

, Tanja J. Hiltl

^a

, Brigitte M. Kudielka

^a

, Jens C. Pruessner

^b

, Stefan Wüst

^a,∗

aInstituteofExperimentalPsychology,UniversityofRegensburg,Universitätsstraße31,93053Regensburg,Germany

bDepartmentofPsychology,McGillUniversity,845RueSherbrookeO,Montréal,QCH3A0G4,Canada

Keywords:

Acutestressresponses HPAaxis

Salivarycortisol Positive/negativeaffect Real-lifestress

a b s t r a c t

TheTrierSocialStressTest(TSST)isthemostwidelyusedlaboratorystressprotocolinpsychoneuroen- docrinology.Despiteitspopularity,surprisinglyfewattemptshavebeenmadetoexploretheecological validityoftheTSST.Inthepresentstudy,31younghealthysubjects(24females)wereexposedtotheTSST about4weeksbeforecompletinganoralexamonaseparateday.Salivarycortisollevelsincreasedsignif- icantlyinresponsetobothstimuli(TSST:F(2.21,66.33)=5.73,p=0.004;oralexam:F(1.98,59.28)=4.38, p=0.017)withsimilarmeanresponsecurvesandsigniﬁcantcorrelationsbetweencortisolincreasesand areasundertheresponsecurves(increase:r=0.67;AUC:r=0.56;bothp≤0.01).Correspondingly,changes inpositiveandnegativeaffectdidalsoshowsigniﬁcantcorrelationsbetweenconditions(increase:positiveaffect:r=0.36;negativeaffect:r=0.50;both:p≤0.05;AUC:positiveaffect:r=0.81;negativeaffect:

r=0.70;bothp≤0.01)whilemeantimecoursedynamicsweresigniﬁcantlydifferent(positiveaffect:

F(2.55,76.60)=10.15,p=0.001;negativeaffect:F(1.56,46.82)=23.32,p=0.001),indicatingthattheoral examhadamorepronouncedimpactonaffectthantheTSST.

Ourﬁndingsprovidenewevidencefortheviewthatcortisolaswellassubjectivestressresponsesto theTSSTareindeedsigniﬁcantlyassociatedwithacutestressresponsesinreallife.

1. Introduction

Hypothalamus-pituitary-adrenal(HPA)axisresponsestoacute stressareconsideredanimportantbiomarkerofindividualstress regulation,moresothanbaselinemeasures.Therefore,psychoneu- roendocrine researchonthelinkbetweenstressand diseasein humansrequiresstandardizedandvalidprotocolstoinducepsy- chologicalstressundercontrolledconditions.Aprotocolthathas widelybeenusedinhealthysubjectsaswellasinvariousclini- calpopulationsformorethan20yearsistheTrierSocialStress Test(TSST)(Kirschbaumetal.,1993,1992;Kudielkaetal.,2009).

However,althoughstressexposureundercontrolledconditionshas advantagesinmanyrespects,itlacksdirectevidenceofecological

∗Correspondingauthor.

E-mailaddresses:Henze@psychologie.uni-regensburg.de (G.-I.Henze),Zaenkert@psychologie.uni-regensburg.de(S.Zänkert), Urschler@psychologie.uni-regensburg.de(D.F.Urschler),

Hiltl@stud.uni-regensburg.de(T.J.Hiltl),Kudielka@psychologie.uni-regensburg.de (B.M.Kudielka),Pruessner@mcgill.ca(J.C.Pruessner),

Wuest@psychologie.uni-regensburg.de(S.Wüst).

validity(DickersonandKemeny,2004).TheusefulnessoftheTSST hasbeenclearlydemonstrated,e.g.instudiesthatfoundsignifi- cantstressresponsedifferencesbetweenpsychiatricpatientsand healthycontrols(Burkeetal.,2005)orinstudiesshowingsignif- icantandplausiblecross-correlationsbetweenpsychologicaland endocrinestressresponses(Schlotzetal.,2008).Buttothebest ofourknowledge,veryfewattemptshavebeenmadetodirectly addressthequestion,ifstressresponsestotheTSSTarerelated toacutestressresponsesinreallife.Anexceptionisastudyby Wolframetal.(2013)whoinvestigatedtheassociationbetween cortisolresponsestotheTSSTandresponsestoagradeddemon- strationlessoninasampleof21studentteachers,buttheyfailed tofindasignificantcorrelation.Itis,however,possiblethatthis studymissedtocapturethecortisolpeakinthereal-lifestresscon- ditionbecausesalivasamplingwasnotpossibleduringthe45min demonstrationlesson.

Tofurther explore the ecologicalvalidity of theTSSTin the presentstudy, wechosea brieforalexam asnaturalistic stres- sor.Theadvantageofthecurrentapproachwasthesimilarityto theTSSTinduration (10min) andcontent(speaking infront of anaudience withtheperceived risk of beingnegatively evalu-

Erschienen in: Psychoneuroendocrinology ; 75 (2017). - S. 52-55

https://dx.doi.org/10.1016/j.psyneuen.2016.10.002

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ated(DickersonandKemeny,2004;Kudielkaand Wüst,2010)).

Wehypothesizedthatwewouldobserveasigniﬁcantassociation betweentheoralexamandtheTSSTwithrespecttocortisoland subjectivestressresponses.

2. Materialsandmethods

Inasampleof31apparentlyhealthystudentsoftheUniver- sityofRegensburg(24women,7men;age:19–32years,M=22.48, SD=4.32)weassessedsalivarycortisolandself-reportedpsycho- logicalstressresponsestotheTSSTandtoanoralpass-failexam thatwaspartofauniversitycourseforbachelorstudentsinpsy- chology.Thistestwastheﬁrstoralexaminthestudycourse.While thepanelconsistedoftwoexaminersintheTSST,onlythestu- dentandthelecturer,inquiringaboutmaintopicsofthepsychology course,werepresentintheroomduringtheoralexam.Bothstress exposures tookplace onweekdaysbetween1:00 and 5:00pm andsubjectswereinstructedtorefrainfromphysicalexerciseand largemealsatleast90minbeforetheonsetoftheassessment.The exposuresfollowedidenticalprotocolsincludingrepeatedsaliva samplingwithcortisolsalivettes(Sarstedt,Nümbrecht,Germany) and affectratingsusing thePositive andNegativeAffectScales (PANAS;(Watsonetal.,1988)).Participantswereaskedtocollect samplesandtoratetheiraffectatminute−30,−20,−10,0,+10, +20,+30and+40relativetostressonset.Duringthebriefstress exposures,nosalivasamplesoraffectratingshavebeencollected.

Allparticipantsprovidedtheirwritteninformedconsentandwere paid20Dorreceivedparticipanthoursfortakingpartinthestudy.

Onaverage26.7(±12.47)daysafterTSSTexposuresubjectscom- pletedtheoralexamaspartoftheirbachelor’sdegree.Asassessed withaninhousequestionnaire,allsubjectsreportedgoodhealth andnopsychologicaltreatmentforthepast24 monthspriorto studyentryorscoredbelowthecut-offvalue(<14)oftheWHO-5 WorldHealthOrganizationWell-BeingIndex(WHO-5;(Toppetal., 2015)).Thirtyparticipantsreportedtobenon-smokers andone participantreported tosmokeless than ﬁvecigarettesper day.

Fourteenof the24females reportedtouseoralcontraceptives.

Itwasmadecleartothesubjectsthatparticipatinginthisstudy wouldinnowayaffecttheoutcomeoftheoralexam,andthatthe examinerwasnotinvolvedinthestudy.

3. Results

An ANOVA for repeated measures with salivary cortisol as dependentmeasureyieldedasigniﬁcantmaineffecttimeforthe TSST(F(2.21,66.33)=5.73,p=0.004,␩²=0.160)andtheoralexam (F(1.98,59.28)=4.38,p=0.017,␩²=0.127)(Fig.1A).Weapplied Greenhouse-Geisser correctionsbecause thesphericityassump- tionswereviolated.Whilemeanpre-stresslevelsinbothconditions were virtually identical, cortisol responses to the TSST were marginallyhigherthanresponsestotheoralexam(maineffectcon- dition:F(1.0,29.0)=3.56,p=0.069,␩²=0.109).Thistrendeffectcan beexplainedbyhigherTSST-comparedtoexam-responsesinmales asdocumentedbyasigniﬁcantinteractioneffectoftimexcondition xsex(F(2.88,83.47)=3.46,p=0.021,␩²=0.107).Responderrates accordingtotherecentlysuggestedcriterionbyMilleretal.(2013) weresimilarinthetwostressexposures,with22subjectsshow- ingacortisolresponsetotheTSSTand18subjectsrespondingto theoralexam.WethenusedPearsoncorrelationstoinvestigate theassociationofTSSTcortisolresponsesandcortisolresponsesto ournaturalisticstressor.Wefoundthatboth,cortisolincreases(i.e.

individualpeaklevelsminusindividualpre-stresslevels)aswellas areasundertheresponsecurves(AUC)asmeasureoftotalcortisol outputweresigniﬁcantlycorrelatedbetweenTSSTandexamcon-

dition(increase:r=0.67,␩²=0.212;AUC:r=.56,␩²=0.314;both p≤0.01;Fig.1BandC).

Furthermore,changesinpositiveandnegativeaffectinresponse totheTSSTandtheoralexamwerealsosigniﬁcantlyassociated (increase:positiveaffect:r=0.36,␩²=0.13;negativeaffect:r=0.50,

␩²=0.25;both:p≤0.05;AUC: positiveaffect:r=0.81, ␩²=0.66;

negative affect: r=0.70, ␩²=0.49; both p≤0.01). Nevertheless, andincontrasttocortisolresponses,meantimecoursedynam- icsinpositiveandnegativeaffectdidsigniﬁcantlydifferbetween conditions(Fig.2).AnANOVAforrepeatedmeasuresrevealeda signiﬁcanttimexconditioninteractionforpositiveaffect(F(2.55, 76.60)=10.15,p=0.001,␩²=0.25)aswellas fornegativeaffect changes(F(1.56,46.82)=23.32,p=0.001,␩²=0.44).Positiveaffect levelspriortotheoralexamwherelowerthanpriortotheTSST.

Theyincreasedsubstantiallyaftertheoralexam whiletheydid notshowariseaftertheTSST.Consistently,negativeaffectrat- ingswhereratherhighpriortotheoralexamfollowedbyadistinct declineafterstress.Incontrast,thenegativeaffectpeaklevelsinthe TSSTconditionwereobservedimmediatelyafterstressexposure hasended.

4. Discussion

Theaimofthepresentstudywastoexploretheecologicalvalid- ityoftheTSST,bycomparing itwitha real-lifeandmeaningful acutepsychologicalstressor.Inasampleof31younghealthysub- jects,wefoundthatsalivarycortisolaswellasaffectresponsesto theTSSTandtoanoraluniversityexamweresignificantlyassoci- ated.ThesefindingssupporttheviewthatTSSTresponsesindeed are significantly associated with acute stress responses in real life.Meansalivarycortisolresponsecurveswhereverysimilarin bothconditionssuggestingasimilarinitialintensityoftheover- allperceivedstressresultinginasubsequentHPAaxisactivation includingareleaseofcortisolfromtheadrenals.However,mean affectresponsecurvesdidsignificantlydifferbetweenconditions.

Whilesubjectsreportedtoberathernervous,anxiousordistressed priortotheoralexam,theirpositiveaffectlevelsincreasedand theirnegativeaffectlevelsdecreasedimmediatelyafterit,apattern thatcanperhapsbeinterpretedassignificantrelief.Thisassump- tionappearsplausibleasthesubjectswereimmediatelyinformed abouttheirperformanceandasallsubjectspassedtheungraded exam.Remarkably, meanaffectratingsclearly differedbetween conditionsalreadyatourfirstmeasurementpoint(−30min).These pre-stressdifferencescouldindicatethattheupcomingexamwas appraisedasbeingmorerelevantthantheparticipationinapsycho- logicalstudyresultinginamoredistinctanticipationresponseprior totheoralexam.Moreover,affectratingspriortotheTSSTexposure mayindicatethatthesubjectshadnoclearexpectationsregard- ingtheTSSTandthattheythusunderratedthestressinducedby this“artificial”scenario(althoughthesubjectscertainlyreceiveda detailedwritteninformationdescribingtheTSST-procedurebefore theysignedtheconsentform).AffectratingsaftertheTSSTdid not suggest thatthe subjectsfelt relieved,perhaps asa conse- quenceofforcedfailuresandperceivedsocial-evaluativethreat.

Duetothepartialmismatchbetweenexpectationspriortoexpo- sureand actualsituational characteristicsof theTSST (e.g.two examinersnotgivingany(non-)verbalsupportivefeedbacketc.) subjectsmayalsohaveperceivedmoreuncontrollabilityduringthe TSSTthanintheoralexam.Thispatterncanperhapsbedescribed as‘worsethananticipated’.Althoughendocrine andpsychologi- calstressresponsestheoreticallyrepresentindicatorsofthesame construct,anapparentinconsistencybetweenthesedomainsisa well-knownphenomenonthat,atleastinpart,canbeexplainedby differentresponsedynamics(Andrewsetal.,2013;Schlotzetal., 2008).

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TSST

-5 0 5 10 15 20 25

oral exam

-5 0 5 10 15 20 r = .67

increase

time [minutes]

-30 -20 -10 0 10 20 30 40

salivary cortisol [nmol/l]

0 5 6 7 8 9 10

TSST oral exam

stress

A B

C

TSST

0 500 1000 1500 2000 2500

oralexam

0 200 400 600 800 1000 1200 1400 r = .56

AUC

Fig.1.(A)Meansalivarycortisolresponses(nmo/l±SEM)totheTSSTandtheoralexamandcorrelationsofcortisol(B)increasesand(C)areasundertheresponsecurve (AUC)betweentheTSSTandtheoralexam.

time [minutes]

-30 -20 -10 0 10 20 30 40

positive affect [test score]

0 25 26 27 28 29 30 31 32

TSST oral exam

A B

stress stress

time [minutes]

-30 -20 -10 0 10 20 30 40

negative affect [test score]

0 11 12 13 14 15 16 17 18 19

Fig.2.Meanresponses(score±SEM)of(A)positiveand(B)negativeaffect(PANASscores±SEM)totheTSSTandtheoralexam.

Ourstudyhasseverallimitations.Firstofall,thedurationofour naturalisticstressoraswellasitspsychologicalelements(acute challenge,uncontrollability,pressuretoperform,social-evaluative threat,fearoffailure)wererathersimilartothoseoftheTSST.While thisisnotalimitationperse–infact,wespecificallysearchedfor anaturalisticstressorwithsufficientintensitythatshowsthese characteristics–itlimitsthegeneralizabilityofourfindings.Our findingsdonotdemonstratecomprehensiveecologicalvalidityof theTSSTforstressresponsesingeneral.Furtherobviousandinter- relatedlimitationsarethesmallsamplesize,particularlythesmall number ofmale subjectsaswellas thelackof controlfor oral contraceptiveusage(OC),ofpotentialspecificeffectsofdifferent OCs(PletzerandKerschbaum,2014)andofmenstrualcyclephase includingovulationinfemalesubjects.Theseshortcomingswere causedbythefactthatexamsshowingtheabovementionedchar- acteristicsarerareatourinstituteandthatonlyhighlymotivated studentsagreetoparticipateinastudywhiletakinganexamthat isrelevantfortheirbachelor’sdegree.However,inasupplemen- taryanalysiswedidnotfindsignificantdifferencesinmeancortisol responsestotheTSSTortheoralexaminfemalesusingversusnot usingoralcontraceptives(allp>0.4formaineffectsOCandtimex

OCinteractions).Onadescriptivelevel,OCusingfemalesshowed onaveragemarginallylowercortisollevelspriortostressexposure whilecortisollevelsafterstressexposurewherealmostidentical.

Insummary,theTSSThasprovenitsusefulnessinnumerous studies.Sofar,however,ourknowledgeonthereal-lifevalidityof theTSSTwasscarce.Inourview,thecurrentstudymadeanimpor- tantcontributiontothevalidationofthisparadigm.Resultsofthe presentstudysuggestthatsalivarycortisolandaffectresponsesto theTSSTaresigniﬁcantlyassociatedwithcorrespondingresponses toabriefacutestressorinreallife.

Contributors

Gina-IsabelleHenze,Sandra Zänkert,DavidUrschler, TanjaJ.

Hiltl,BrigitteM.Kudielka,JensC.Pruessner,andStefanWüst.

JCP,BMKandSWplannedthestudy;GIH,SZ,DUandTJHpre- paredandperformedthestudy;GIHandSWwrotetheﬁrstdraftof themanuscript;allauthorscontributedtotheﬁnalversionofthe manuscript.

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55 Conﬂictofinterest

Allauthorsdeclarenoconﬂictofinterestrelatedtothisstudy.

Roleofthefundingsource

Thisresearchdidnotreceiveanyspeciﬁcgrantfromfunding agenciesinthepublic,commercial,ornot-for-proﬁtsectors.

Acknowledgements

WethankFabienneRopeter,PetraEbenschwangerandCorinna Stammingerfortheirhelpinrunningtheexperimentalsessionsand dataentry.

Thisresearchdidnotreceiveanyspeciﬁcgrantfromfunding agenciesinthepublic,commercial,ornot-for-proﬁtsectors.

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