Longitudinal effects of the SSRI paroxetine on salivary cortisol in Major Depressive Disorder

Page 1

Psychoneuroendocrinology (2015) 52, 261—271

Available online at www.sciencedirect.com

ScienceDirect

j ourna l h om epa ge : www.elsev ier .com/ locate /psyneuen

Longitudinal effects of the SSRI paroxetineon salivary cortisol in Major DepressiveDisorder

Henricus G. Ruhéa,b,∗,1, Sharina J. Khoenkhoena,1,Koen W. Ottenhofa, Maarten W. Koetera, Roel J.T. Mockinga,Aart H. Schenea,c,d

a Program for Mood Disorders, Department of Psychiatry, Academic Medical Center, University ofAmsterdam, Amsterdam, The Netherlandsb University of Groningen, University Medical Center Groningen, University Center for Psychiatry, Mood andAnxiety Disorders, Groningen, The Netherlandsc Department of Psychiatry, Radboud University Medical Center, Nijmegen, The Netherlandsd Donders Institute for Brain, Cognition and Behavior, Radboud University, Nijmegen, The Netherlands

Received 8 July 2014; received in revised form 10 October 2014; accepted 30 October 2014

KEYWORDSSSRI;Depressive disorder;HPA-axis;Cortisol;Treatment response;Remission

Summary Hypothalamic-pituitary-adrenal (HPA)-axis dysregulation is a prominent findingin more severe Major Depressive Disorder (MDD), and is characterized by increased baselinecortisol levels at awakening (BCL), blunted cortisol awakening response (CAR) and increasedarea under the cortisol curve (AUC). Selective serotonin reuptake inhibitors (SSRIs) appear tonormalize HPA-axis dysfunction, but this is hardly investigated longitudinally.

We studied salivary BCL, CAR and AUC at awakening and 30 min thereafter. We comparedmeasurements in initially drug-free MDD-patients with healthy controls (HCs) at study-entry.In patients, we repeated measures after 6 and 12 weeks’ treatment with the SSRI paroxetine.Non-responding patients received a randomized dose-escalation after six weeks’ treatment.

We found no significant study-entry differences in BLC, CAR or AUC between MDD-patients(n = 70) and controls (n = 51). In MDD-patients, we found general decreases of BCL and AUCduring paroxetine treatment (p ≤ 0.007), especially in late and non-responders. Importantly,while overall CAR did not change significantly over time, it robustly increased over 12 weeksespecially when patients achieved remission (p ≤ 0.041). The dose-escalation intervention didnot significantly influence CAR or other cortisol parameters.

∗ Corresponding author at: Room 5.16, Mood and Anxiety Disorders, University Center for Psychiatry, University Medical Center GroningenHanzeplein 1, 9700 RD Groningen, The Netherlands. Phone: +31 50 361 2367; fax: +31 50 361 1699.

E-mail address: [email protected] (H.G. Ruhé).1 Both authors contributed equally to the manuscript.

http://dx.doi.org/10.1016/j.psyneuen.2014.10.0240306-4530/© 2014 Elsevier Ltd. All rights reserved.

Page 2

262 H.G. Ruhé et al.

In conclusion, paroxetine seems to interfere with HPA-axis dysregulation, reflected in significantoverall decreases in BCL and AUC during treatment. Paroxetine appears to decrease HPA-axisset-point in MDD, which might result in increased HPA-axis activity over time, which is furtherimproved when patients achieve remission (ISRCTN register nr. ISRCTN44111488).© 2014 Elsevier Ltd. All rights reserved.

1

TmtpietD2hfltC2ttbctet2(l(es

aiSet—i(HdMhosc2po2

ore

HoHtegtch(r(t(imld

rastpptii2eti(1eaa

2

2

Tstet al., 2009). Following approval by the institutional ethi-cal committee and written informed-consent, we recruiteddrug-free outpatients. Inclusion criteria were: MDD deter-

. Introduction

he hypothalamic-pituitary-adrenal-axis (HPA-axis) is theain endocrinological regulator of allostasis. A robust short-

erm HPA-axis response to acute stress may confer optimalhysiological function and reflect adaptability or reactiv-ty to environmental demands (Kudielka et al., 2009; Clowt al., 2004). However, more enduring HPA-axis hyperac-ivity is seen in approximately 73% of patients with Majorepressive Disorder (MDD) (Vreeburg et al., 2009; Holsboer,000). In general in MDD, HPA-axis alterations are found as (I)yperactivity: increased cortisol in blood and cerebrospinaluid, (II) non-suppression: higher rates of non-suppressiono the dexamethasone suppression test and dexamethasone-RH (DEX-CRH) test (Heuser et al., 1994; Stetler and Miller,011), and/or (III) decreased HPA-axis feedback inhibi-ion. These factors can be integrated by the hypothesishat impaired glucocorticoid receptor (GR)-mediated feed-ack inhibition (non-suppression) leads to a higher baselineortisol secretion (hyperactivity), which diminishes reac-ive capacity (Pariante, 2009). These HPA-disturbations arespecially observed in severe/melancholic MDD and/or inpa-ients with MDD (Kunugi et al., 2010; Stetler and Miller,011). However, decreased HPA-axis activity was also foundStetler and Miller, 2005; Huber et al., 2006), in particu-ar during chronic depressive episodes (duration >2 years)Kunugi et al., 2010). This differential stress-effect mightxplain contradictory findings of HPA-axis activity in MDDtudies.

Selective Serotonin Reuptake Inhibitors (SSRIs) arentidepressant drugs extensively used in MDD. Interest-ngly, besides increasing serotonergic neurotransmission,SRIs might also change HPA-axis disturbances (Vermettent al., 2006; Aihara et al., 2007). Only one randomizedrial has been performed — in generalized anxiety disorder

and reported reductions in HPA-axis hyperactivity dur-ng treatment with the SSRI escitalopram versus placeboLenze et al., 2010). Furthermore, in healthy controls (HCs),PA-axis awakening response significantly increased after sixays of citalopram versus placebo (Harmer et al., 2003). InDD, the SSRI fluoxetine decreased corticotropin-releasingormone (CRH) (indicative of HPA-hyperactivity) in a smallpen study (De Bellis et al., 1993). A 16 weeks opentudy with citalopram in 20 MDD-patients showed signifi-ant decreases in cortisol (after DEX-CRH) (Nikisch et al.,005). However, after 5 weeks of treatment with the SSRIaroxetine or the non-SSRI amitriptyline, HPA-axis activitynly decreased in amitriptyline responders (Deuschle et al.,003).

Importantly, effects of antidepressants, including SSRIs,n the HPA-axis seem to occur mainly in MDD-patientsesponsive to treatment (Deuschle et al., 2003; Nikischt al., 2005). Therefore, it remains largely unclear whether

masd

PA-axis abnormalities resolve as a result of SSRI treatment,r due to clinical improvement (state effect). Nevertheless,PA-axis dysregulation has also been observed in remit-ed MDD patients, indicating a persistent trait (Bhagwagart al., 2003; Lok et al., 2011). Therefore, it has been sug-ested that resolving HPA-axis abnormalities during MDDreatment indicates SSRI response. This may have importantlinical implications, also explaining why persistent HPA-axisyperactivity during SSRI treatment predicts MDD relapseAppelhof et al., 2006; Hardeveld et al., 2014), althoughelapse has also been associated with HPA-hypoactivityBockting et al., 2012). These HPA-axis abnormalities mayherefore form novel targets for (add-on) interventionsPariante, 2009). However, to date, studies longitudinallynvestigating the HPA-axis in MDD-patients during SSRI treat-ent to disentangle antidepressant and state effects are

argely lacking, especially with a randomized controlled trialesign.

To investigate (I) HPA-axis activity and awakeningesponse in MDD, (II) its modulation by SSRIs, and (III) itsssociation with treatment response, we repeatedly mea-ured salivary cortisol responses to awakening in patientsreated for 12 weeks with paroxetine. First, we comparedatients to matched HCs at study entry. Subsequently, in theatients, we investigated changes in HPA-axis activity overime during treatment. Moreover, we included a random-zed, double-blind, placebo-controlled SSRI dose-escalationn non-responders after six weeks of treatment (Ruhe et al.,009), enabling investigation of causal effects of differ-nt paroxetine doses on HPA-axis activity. We hypothesizedhat (I) MDD-patients would have increased HPA-axis activ-ty and decreased awakening response compared to HCs;II) in patients, HPA-axis dysregulation would improve during2 weeks paroxetine-treatment; (III) this change would bespecially present in treatment responders (and remitters),nd (IV) effects on the HPA-axis would be more outspokenfter dose-escalation for non-responders.

. Methods

.1. Participants

his study reports a secondary research question in a largertudy (ISRCTN register nr. ISRCTN44111488; http://www.rialregister.nl/trialreg/admin/rctview.asp?TC=193) (Ruhe

ined by the structured clinical interview for DSM-IV (SCID),ge 18—70 years and a Hamilton Depression Rating Scalecore (HDRS17-score) >18. All participants were drug-naive orrug-free for >4 weeks and, if treated before, had received

Page 3

ol in

ctma(i

2

2Aptvtb3smradi

2Witdd(w

2Wamfuigc(dtuatwyacSd

s

Longitudinal effects of the SSRI paroxetine on salivary cortis

≤1 antidepressant (other than paroxetine; at an effectivedose for >4 weeks) for the present MDD-episode.

Exclusion criteria were: bipolar disorder, psychotic fea-tures, neurological cognitive impairments, primary anxietyand/or substance abuse disorders, severe suicidal ideationand pregnancy. We allowed (low dose) benzodiazepine use,and excluded patients who used drugs which directly affectHPA-axis activity (e.g. systemic corticosteroids).

We recruited HCs by advertisements. HCs were in goodphysical health and never used psychotropic medication.Exclusion criteria for HCs were SCID-positive current orlifetime psychiatric disorder(s), including addiction disor-ders, Beck Depression Inventory score >9, >4 alcoholicbeverages/day (last month) or a 1st-degree relative withpsychiatric disorder(s). HCs could have incidentally usedillicit drugs; drug-use one month prior to participation wasnot allowed.

2.2. Intervention

Patients were treated at the outpatient department of theProgram for Mood disorders of the Academic Medical Cen-ter. After study-entry, patients were treated open labelwith paroxetine 20 mg/day for 6 weeks. After 6 weeks(T0), responders (≥50% decrease of symptoms) contin-ued treatment with paroxetine 20 mg/day for another 6weeks (T1). Non-responders were randomized at T0 by acomputer-program and received either a true paroxetine, ora placebo dose escalation, added to the initial dose of parox-etine 20 mg/day (Supplemental Fig. S1). Dose-escalationconsisted of incremental steps of one capsule every 5 days(to a maximum of 50 mg/day). Paroxetine serum concentra-tions (PSC) were measured at T0 and T1 with a validatedHPLC-MS/MS method (therapeutic range 10—75 �g/L). Formore details see Ruhe et al. (2009). Clinical measurementsfor patients were scheduled at study-entry, T0 and T1. HCswere measured at study-entry only.

2.3. HPA-axis

Several studies have indicated that salivary cortisol lev-els are valid measures of HPA-axis activity (Westermannet al., 2004; Kirschbaum and Hellhammer, 1994; Gallagheret al., 2006; Wust et al., 2000), particularly the physiologicrise in cortisol within 30 min after waking up (Clow et al.,2004). This rise has been hypothesized to be able to quantifyboth HPA-activity (cortisol at awakening; baseline cortisollevel; BCL), and HPA-axis feedback inhibition (differencebetween cortisol 30 min after awakening and awakening;Cortisol Awakening Response; CAR), which are both reflectedin the area under the curve (AUC). These measures showgood intra-individual stability across time and can quantifysubtle changes in HPA-axis regulation, thereby providing avalid method to study changes in HPA-axis activity over atreatment period (for review see Fries et al. (Fries et al.,2009)).

After instruction, all subjects collected salivary sam-

ples at home, immediately after awakening and 30 minthereafter. Waking time and the time of the second salivasample were recorded. Samples were refrigerated andbrought to the hospital at the next visit. To avoid blood

vn(c

MDD 263

ontamination, participants refrained from brushing theireeth or eat before collecting both samples. Cortisoleasurements were obtained at study-entry, T0 and T1,

nd stored at −20 ◦C until analysis by radioimmunoassayIBL Hamburg; designed for saliva samples). Intra- andnter-assay variations were 5.1% and 6.5%, respectively.

.4. Statistics

.4.1. Data cleaning and missing valuesll cortisol-measures were normally distributed. As donereviously (Vreeburg et al., 2009), we considered 160% ofhe highest BCL (41.4 nmol/L) as maximum possible CARalue (70 nmol/L) (Clow et al., 2004). Because salivary cor-isol levels above this limit are likely contaminated bylood and may distort further analyses, we considered/235 measurements as missing. We calculated CAR as thealiva cortisol level measured at 30 ± 10 min after awakeninginus the BCL. Nineteen measurements outside this ±10 min

ange were also considered missing. AUC was calculateds BCL + ½*CAR (Fig. S2). In order to quantify how missingata influenced results we also performed our analyses inmputed datasets, which is explained in the supplemental.

.4.2. Treatment responsee operationalized treatment response by dividing patients

nto three response groups based on HDRS17-score rela-ive to the pre-treatment score: (I) early responders (≥50%ecrease on HDRS17-score at T0), (II) late responders (≥50%ecrease on HDRS17-score at T1) and (III) non-responders<50% decrease on HDRS17-score at T0 and T1). Remissionas defined as a HDRS17 score ≤7.

.4.3. Analysese used IBM-SPSS v.19.0 for all analyses. Clinical data were

nalyzed on intention to treat (ITT) basis and for clinicaleasures of drop-outs we used a last observation carried

orward approach. For comparisons of patients vs. HCs, wesed a propensity score (PS1) (Bartak et al., 2009) represent-ng the predicted probability for a case to belong to a certainroup, calculated in a binary logistic model with the desiredonfounders (including age, gender, alcohol-use, smokingKudielka et al., 2009) and race (Hajat et al., 2010)) as pre-ictors (Rosenbaum and Rubin, 1983). For comparison of thehree response groups, we considered age, gender, alcohol-se, smoking, race, and body mass index (BMI) at study-entrys covariates, for which we finally included only variableshat differed trendwise (p < 0.1) univariately. In addition,e included awakening time as a fixed covariate in all anal-ses (Stalder et al., 2009). Because non-responding patientst T0 were randomized to receive a dose-escalation or not,onfounders were assumed to be equally distributed (Table1) resolving the need for propensity scores for analyses ofose-escalation.

For comparisons between groups, we used Linear Regres-ion Analysis with BCL, CAR and AUC as dependent

ariables and group (patients and HCs, final remitters andon-remitters, dose-escalation) as independent variableincluding the propensity score and/or covariates as indi-ated).

Page 4

264 H.G. Ruhé et al.

Referred for assessment of eligibility(n= 278)

Sta rt open paroxet ine 20mg/d ay(n= 70)

Randomizat ion of Non-responders open phase (n= 42)

Excluded before open phase- In vited but withdrew (n= 27)- Ineligible by crite ria (n= 8 8)- Ineligible by current use of antidepressan ts (n= 37)- Overall refusal to participate (n= 47)- Excluded other reason s (n=9)

Dropout open phase paroxetine 20mg/day (n= 11)- Inefficacy (n= 1)- Adverse effects (n= 3)- Other rea sons (n= 6)- Withdrawn after interim (n= 1)

Responders (n= 17)

Paroxet ine do se-escalat ion (n= 21)[paroxetine30-50mg/day]

Placebo do se-escalat ion (n= 21)[paroxetine 20mg/day + placebo 10-30mg/day]

Paroxet ine continuation (n= 17)[paroxetine 20mg/day]

Analyzable clinical data (n= 20)- Wk 12 completer (n= 20)

Analyzable clinical data (n= 18)- Wk 12 completer (n= 16)

Analyzable clinical data (n= 17)- Wk 12 completer (n= 17)

Dropout Rand. Pha se (n= 5)- In efficacy (n= 3)- Adverse effects (n= 3)- Other reason s (n= 1)

Dropout Rand. Pha se (n= 0)- In efficacy (n= 0)- Adverse effects (n= 0)- Other reason s (n= 0)

Dropout Rand. Pha se (n= 1)- In efficacy (n= 0)- Adverse effects (n= 0)- Other reason s (n= 1)

Enr

ollm

ent

Study-entry

Ope

nph

ase

T0

Ran

dom

ized

phas

eo r

cont

inua

tion

T1

tien

(usef

crtiagtfi(

mbvasdit

3

3

SpTrntt

rW3drw5aw4sdpo

3

Ts(phm9pmegcetdid not significantly differ for other variables (all p > 0.12).,

Figure 1 Pa

To investigate changes in cortisol parameters over timeduring treatment) in all patients and patient subgroups, wesed Linear Mixed Model Analyses, which enable to mea-ure changes of parameters over time and the interactionffects of subgroups*time (Jaeger, 2008), while correctingor covariates.

In the mixed models investigating treatment response,ortisol parameters were the dependent variable andesponse group (early, late and non-response), follow-upime, measurement moment and their interactions werendependent variables. We corrected results for age, gendernd for variables that differed between the three responseroups (p < 0.1; i.e. alcohol use and smoking) and awakeningime as a time-dependent covariate. Improvement of model-t was judged by decreasing Akaike Information criterionAIC).

With respect to quantification of remission effects, twoodels were applied. One model investigated differencesetween ‘final remitters and non-remitters’ as a group-ariable (i.e. differences between effects in final remittersnd non-remitters as a fixed variable over time), while theecond model investigated the effect of ‘remission as a time-ependent state-factor’ (i.e. difference between subjectsn remission vs. non-remitters at a certain time point duringreatment which is changing over time).

. Results

.1. Patient disposition

eventy patients (mean age 42.5 ± 7.8) started open labelaroxetine at study-entry (see patient-flow in Fig. 1). At0, 11 patients had dropped out before week 6. The ITT

esponse rate in the open phase was 17/70 (24.3%); so 42on-responding patients were randomized at T0 and enteredhe double-blind phase. A total of 36 patients completedhe 6 week randomization phase; in addition the 17 T0

FHva

t disposition.

esponders also completed another 6 weeks of treatment.e obtained at least 1 HDRS17 score after randomization for

8 patients, therefore yielding 55 patients for the longitu-inal analyses. Of these 55 patients 17 (30.9%) were earlyesponders, 18 (32.7%) were late responders and 20 (36.4%)ere non-responders. After data-cleaning we obtained 63,2 and 48 valid cortisol measurements at study-entry, T0

nd T1, respectively. We recruited 51 controls of whome obtained valid cortisol measurements at study-entry for7 subjects. Subjects without valid cortisol measures wereignificantly younger, and of non-Caucasian heritage, butid not differ on other demographic characteristics, or (foratients) depression-related characteristics (data availablen request).

.2. Population characteristics

he 70 patients had a mean HDRS17 of 25.2 ± 4.4 (SD) attudy entry, on average indicating severe MDD. Fourteen20%) had a comorbid (secondary) anxiety disorder (elevenanic disorder/agoraphobia, three specific phobia, but nonead a posttraumatic stress disorder (PTSD)), 52 (74.3%) hadelancholic features, 31 (41.3%) had a recurrent MDE and

(12.9%) had a MDE for >2 years. Compared to controls,atients had significantly lower education-levels and wereore often married and/or divorced and of non-Caucasian

thnicity (Table 1). After randomization at T0, patientroups did not differ significantly regarding study-entryharacteristics (Table S1). With regard to further analyses,arly and late responders smoked and drank trendwise morehan non-responders (p ≥ 0.06; Table S2). Response groups

inal remitters (n = 15) had significant lower study-entryDRS17 scores than final non-remitters (n = 55; 22.4 ± 2.4s. 26.0 ± 4.5; p = 0.004) but did not differ otherwise (datavailable on request).

Page 5

Longitudinal effects of the SSRI paroxetine on salivary cortisol in MDD 265

Table 1 Characteristics of patients and healthy controls.

MDD patients (n = 70) Healthy controls (n = 51) Significancea

Age (yrs ± SD) at study entry 42.5 ± 7.8 42.4 ± 8.4 0.991SexFemale, n (%) 46 (65.7) 33 (64.7) 1.000Marital state, n (%)Never married 22 (31.4) 28 (54.9) 0.010Married 25 (35.7) 15 (29.4)Divorced 21 (30.0) 4 (7.8)Widowed 1 (1.4) 1 (2.0)Education, n (%)Low 13 (18.8) 0 (0.0) <0.001Intermediate 42 (60.9) 16 (31.4)High 14 (20.3) 35 (68.6)Alcohol use (units/wk ± SD) 5.8 ± 10.7 6.9 ± 6.9 0.523Current smoking (cigarettes/day ± SD) 10.7 ± 12.4 6.9 ± 9.6 .079Race, n (%)Caucasian 38 (54.3) 45 (88.2) 0.001Creole 14 (20.0) 5 (9.8)Asian 11 (15.7) 1 (2.0)Other 7 (10.0) 0 (0.0)MDE descriptivesHDRS17 (± SD) 25.2 ± 4.4 N/ARecurrent MDD (n(%)) 30 (42.9)Episode >2 years (n(%)) 9 (13.0)Melancholic subtype (n(%)) 52 (74.3)Waking up time (h ± SD) 07:22 ± 1:45 07:20 ± 1:27 0.912Cortisolparameters b

BCL (nmol/L ± SE) 12.9 ± 1.1 14.4 ± 1.3 0.388CAR (nmol/L ± SE) 5.9 ± 1.2 6.3 ± 1.4 0.818AUC (nmol/L ± SE) 16.2 ± 1.0 17.6 ± 1.2 0.399

Abbreviations: AUC = area under the curve; BCL = baseline cortisol level; CAR = cortisol awakening response; HDRS17 = 17-item HamiltonDepression Rating Scale; MDD = Major Depressive Disorder.

a /mixed models as appropriate.ed on dataset without multiple imputation. See also Fig. S2.

3.4.1. Association with treatment responseAs a next step, we investigated differences in changes inBCL, CAR and AUC over time between the three response

Determined by chi-square/independent samples t-test/ANOVAb Corrected for propensity score and awakening time. Means bas

3.3. Cortisol parameters at study-entry

Although mean BCL, CAR and AUC were numerically lower inpatients compared to HCs, these differences were not sig-nificant at study-entry (all p > 0.24 uncorrected; p ≥ 0.39)corrected for PS1 and awakening time (Table 1/Fig. S2).In the patient-group, cortisol parameters at study-entrywere not associated with HDRS-scores (all p ≥ 0.11; LinearRegression). At study entry, response groups did not differsignificantly with respect to BCL, CAR or AUC at study entry(p > 0.103). We neither observed significant differences instudy-entry BCL, CAR and AUC between final remitters andfinal non-remitters (all p > 0.19; corrected for HDRS17 atstudy entry and awakening time).

3.4. Changes in cortisol parameters over timeduring paroxetine treatment

On average, BCL and AUC values both decreased significantlyover time (F1,50.703 = 8.090; p = 0.006 and F1,51.921 = 7.756;p = 0.007, respectively, Fig. 2), while CAR did not signifi-cantly change during the study (F1,49.135 = 0.047; p = 0.830).

Figure 2 Changes in cortisol parameters over time (allpatients).

Page 6

266 H.G. Ruhé et al.

Figure 3 Changes in cortisol parameters over time byr

giep(atcp(p

di

3eFtai(Fcvtt

(iLrCcw

3d

AHaaFdt

4

Tbmeasurements of treatment with paroxetine in the MDD-

esponse groups.

roups in a mixed model, by testing response-group*timenteractions (correcting for alcohol use, smoking and awak-ning time). Because by design late and non-respondingatients received different dosages of paroxetine after T0randomization of only non-responders), we added PSCss additional time-dependent covariate, which improvedhe models (based on lower AIC). We found signifi-ant response*time interactions for AUC (F2,42.433 = 3.976;

= 0.026) and a trendwise interaction for and BCLF2,42.832 = 2.335; p = 0.11), but not for CAR (F2,44.753 = 0.201;

= 0.819, Fig. 3). In late and non-responders we observed a

pom

Figure 4 CAR in final remitters vs non-remitters.

ecrease in AUC while in early responders the AUC slightlyncreased over 12 weeks of treatment.

.4.2. Association with remission of the depressivepisodeor final remitters and non-remitters, changes in CAR overime differed significantly, despite comparable CAR-valuest study-entry. Final remitters showed a significant increasen CAR, while CAR in final non-remitters did not changefinal-remission*time interaction F1,52.571 = 4.400; p = 0.041;ig. 4). Although by itself PSCs were not significantly asso-iated with CAR (F1,62.130 = 0.031; p = 0.860), adding thisariable contributed significantly to this model,(decreasinghe AIC). AUC and BCL did not differentially change overime for final remitters versus non-remitters (all p > 0.37).

Additionally, to investigate whether remission statuseither at T0 or T1) was associated with higher CARs, wencluded remission as a time-dependent variable in theinear Mixed Model Analyses. Indeed, this showed thatemission, at any time-point, was associated with higherARs (F1,80.519 = 5.682; p = 0.019). This association did nothange over time as the remission status*time interactionas not significant (p = 0.673).

.5. True paroxetine versus placeboose-escalation after randomization

fter randomization groups did not differ significantly forDRS17 or cortisol measures at T0 (all p > 0.18; data avail-ble on request). Remission rates were 3 (14.3%) in the truend 2 (9.5%) in the placebo-dose-escalation groups (p = 1.000isher’s Exact). Dose-escalation after 6 weeks of treatmentid not significantly affect BCL, AUC or CAR-courses (condi-ion*time interaction; all p > 0.08; Table 2).

. Discussion

his study investigated differences in salivary cortisoletween HCs and MDD-patients and the effects on cortisol

atients. We found no significant differences in BCL, CARr AUC between controls and MDD-patients. Before treat-ent, BCL, CAR and AUC at study-entry were also similar

Page 7

Longitudinal effects of the SSRI paroxetine on salivary cortisol in MDD 267

Table 2 Changes in cortisol parameters for placebo- and true dose-escalation groups.

Placebo dose-escalation True dose-escalation

T0 T1 T0 T1

AUC nmol/L 12.4 ± 1.5 11.7 ± 1.6 13.2 ± 1.3 11.3 ± 1.6BCL nmol/L 8.9 ± 1.3 9.6 ± 1.5 10.3 ± 1.2 7.5 ± 1.5CAR nmol/L 7.1 ± 1.8 2.6 ± 1.8 5.7 ± 1.6 6.7 ± 1.7

Between T0 (randomization to dose escalation) and T1 we found no significant differences in changes in cortisolparameters (mean ± SE)between patients who received placebo dose-escalation versus patients who received real dose-escalation (p > 0.08; Linear Mixed ModelAnalysis). Analyses based on 17 patients receiving a placebo dose-escalation and 19 patients receiving a true dose-escalation.

rtisol

sHeccii2rcH2CabbcabaicpuCp(CrrBhH(S

4t

OAd

Means based on dataset without multiple imputation.AUC = area under the curve, BCL = baseline cortisol level, CAR = co

in (early/late) final responders versus non-responders andin final remitters and non-remitters. More specifically, afterparoxetine-treatment, we observed a decrease of BCL andAUC in MDD-patients over time. Especially in early respon-ders the AUC increased over time, and interestingly, robustincreases in CAR were found in patients who achieved remis-sion from MDE while no increases in AUC or CAR, wereobserved in late/non-responders and non-remitters, respec-tively. Furthermore, remission status during treatment wassignificantly associated with higher CARs. The randomizeddose-escalation in 42 non-responders 6 weeks after study-entry did not significantly influence BCL, AUC or CAR.

4.1. Cortisol parameters at study-entry

4.1.1. HyperactivityOur hypothesis of HPA-axis hyperactivity in MDD-patientscompared to controls had to be rejected. Moreover, ournumerical results even indicate lower HPA-axis activ-ity. However, given the small differences, our study wasclearly underpowered (power = 0.12 for a double-sidedtest at ˛ = 0.05) to significantly detect these differencesrelative to HCs at study-entry (Fig. S2). Previous stud-ies comparing MDD-patients and HCs concerning cortisolparameters showed inconsistent results, although a recentmeta-analysis of 361 studies in 18,454 individuals reportedHPA-axis hyperactivity with small effect sizes in outpatientpopulations with MDD (Stetler and Miller, 2011).

4.1.2. Awakening responseAlthough the CAR was indeed numerically lower in ourpatient group, we could not confirm our hypothesis ofdecreased HPA-axis awakening response in patients versuscontrols. Evidence exists for a blunted CAR in MDD (Stetlerand Miller, 2005; Huber et al., 2006) and Seasonal Affec-tive Disorder (SAD) during winter (Thorn et al., 2011)which might be associated with a change in diurnal sleep-wake rhythm or lack of social contacts (Stetler and Miller,2005). However, also higher CARs (Pruessner et al., 2003;Bhagwagar et al., 2005; Vreeburg et al., 2009) were reportedin MDD-patients compared to HCs.

4.1.3. Explaining inconsistenciesSome explanations for these inconsistencies should be con-sidered. First, previous studies show larger effects in moresevere MDD-populations (Stetler and Miller, 2011). However,

2Sefi

awakening response.

ince we also selected an average severe group (meanDRS17 = 25.2), this does not seem plausible. Second, differ-nt subpopulations and (omission of) correction for differentonfounding variables (Vreeburg et al., 2009) may providelarification. Indeed, different disease duration, comorbid-ty, depression severity and subtypes of MDD affect findingsn HPA-axis abnormalities (Kunugi et al., 2010; Shelton,007; Lamers et al., 2013). Atypical depression and SADesult in HPA-axis hypoactivation (Thorn et al., 2011), inontrast to melancholic depression being characterized byPA-axis hyperactivation (Kunugi et al., 2010; Lamers et al.,013), but this is equivocal (Stetler and Miller, 2011). HigherARs were especially found in association with, more severenhedonia (Wardenaar et al., 2011), which was replicatedy Veen et al. (2011) reporting significant correlationsetween CAR and general distress symptoms. Therefore,orrection for differences in depression duration or subtype,nhedonia and general distress should ideally be applied,ut are statistically not meaningful (and even inappropri-te) in relatively small samples like ours. Nevertheless,n our moderate to severely ill, predominantly melan-holic (>74% of the patients were melancholic) depressedatients without comorbid diseases like PTSD, these factorsnlikely will explain our results. Although — indeed — meanAR at study-entry was numerically lower in chronic MDD-atients (0.60 ± 3.56 nmol/l [SE]; n = 9) versus non-chronic6.14 ± 1.21 nmol/l) MDD-patients, these differences in BCL,AR or AUC were not significant (p = 0.61; p = 0.18; p = 0.73,espectively; post hoc). Therefore, in our MDD-sample itemains speculative why we found non-significantly lowerCL- and CAR-levels at study entry. Instead of HPA-axisyperactivity, these observations might indicate bluntedPA-axis activity and diminished awakening response

Stetler and Miller, 2005; Huber et al., 2006; Chida andteptoe, 2009), which improved after remission (see below).

.2. Changes in cortisol parameters duringreatment and association with treatment response

ne robust finding is the significant decrease in BCL (andUC) during treatment, suggesting that SSRI treatmentecreases the cortisol ‘setpoint’ (Holsboer, 2000; Schule,

007). Previous studies also reported a decreasing effect ofSRIs on HPA-axis hyperactivity (Nikisch et al., 2005; Buhlt al., 2010; Lenze et al., 2010), although contradictoryndings exist (Deuschle et al., 2003; Bschor et al., 2012).

Page 8

2

Iis

BDctmiBaiano(mnlT

wtsrfPevia2o2Iotspspsroar

arvasr22itbeCr

aetcew((ba

dcorbp(eo

dcnaerHHtTstwetnhasn

4

MpMqccttNoofr

68

n theory, lowering the cortisol setpoint could facilitatemprovement of HPA-axis awakening response which wasuggested to be blunted in MDD (Pariante, 2009).

While other studies predominantly reported effects onCL only in treatment responders (Nikisch et al., 2005;euschle et al., 2003), we observed decreases in AUC espe-ially in late and non-responders, which was significant forhe AUC and showed a trend for BCL. Furthermore, at alleasurements over the treatment period, CAR was numer-

cally higher in the early response group (n.s.; Fig. 3).ecause the AUC represents a combined measure for BCLnd CAR, these data together are suggestive of an increasen CAR without changes in BCL in early responders and

decrease in BCL and no change in CAR in late andon-responders. Since groups did not differ significantlyn study-entry HDRS17-scores, other MDD-characteristicsduration of current episode, melancholic features) and HPA-easures, it remains elusive what differentiates late and

on-responders from early responders and/or whether theate/non-responders are more severely disturbed (Fig. 3 andable S2).

Importantly, we found that especially achieving remissionas associated with increases in CAR during paroxetine-

reatment. This corroborates findings that in a large sample,ignificantly higher CARs were found in remitted patientselative to controls (Vreeburg et al., 2009) which was alsoound in drug-free remitted patients (Aubry et al., 2010).ost hoc, in our sample fifteen remitters had higher CARs atndpoint than controls at study-entry (11.1 ± 2.5 nmol/l [SE]ersus 6.2 ± 1.3 nmol/l [SE], respectively (p = 0.08)). CARncreases could be interpreted as a return of normal HPA-axisctivity (Kudielka et al., 2009; Clow et al., 2004; Pariante,009). A decrease in BCL might in fact increase the rangef the awakening response, as reported before (Holsboer,000; Buhl et al., 2010; Lenze et al., 2010; Schule, 2007).ndeed, when we post hoc associated (repeated) measuresf CAR with BCL, we found a significant inverse associa-ion between BCL and CAR, which, in addition, becametronger over time (BCL*time interaction F1,91.707 = 4.388;

= 0.039), while remission-status at T0 or T1 remained aignificant independent predictor for CAR (F1,82.130 = 4.639;

= 0.034; all corrected for awakening time). These resultsuggest that paroxetine treatment improves HPA-awakeningesponse (CAR) by a stronger inverse association with BCLver time of treatment (when BCL decreases), where inddition occurrence of remission further improves HPA-axisesponsiveness.

Increases in CAR as a representation of restored HPA-axisctivity seems at odds with associations of higher CAR withisks for MDD. Furthermore, CAR was also increased in indi-iduals with a parental history of MDD (Vreeburg et al., 2010)nd in people with SAD (Thorn et al., 2011). In a prospectivetudy, young adults with higher CARs had significant moreisk to develop a depressive episode during one (Adam et al.,010) and 2.5-year follow-up (Vrshek-Schallhorn et al.,013). We previously showed that increased HPA-axis activ-ty (at 8:00 and 22:00 h) exists in highly recurrent but remit-ed MDD-patients (Lok et al., 2011). In a large population

ased study, higher CARs predicted recurrence (Hardeveldt al., 2014). These findings could be interpreted as that highARs also represent a trait marker for MDD-vulnerability orecurrence. Alternatively, although speculative, high CAR is

scis

H.G. Ruhé et al.

ssociated with improved cognition (Law et al., 2013; Evanst al., 2011). Higher CARs might thus represent an adap-ive phenomenon: as a ‘preparation of the day’ to increaseognitive compensation (e.g. for daily hassles) and improvexecutive functioning in patients with (recurrent) MDD evenhen in remission. If this adaptive phenomenon collapses

e.g. after exhaustion and decreased/blunted CARs), anew) depressive episode might occur, which is corroboratedy the finding that especially HPA-hypoactivity was associ-ted with relapse (Bockting et al., 2012).

In the present study we additionally investigated theose—response relationship of paroxetine with respect tohanges in HPA-axis disfunction. However, the second phasef six weeks true paroxetine versus placebo dose-escalationevealed no significant differences in BCL, AUC or CARetween dose-groups. This null-finding corroborates withrevious observations that dose-escalation of paroxetineand other SSRIs) does not improve symptomatology (Ruhet al., 2006; Adli et al., 2005) and neither increases SERT-ccupancy (Ruhe et al., 2009).

An explanation for the changes in cortisol measuresuring treatment with paroxetine and the absence of asso-iations with PSC or paroxetine dose, might lie in theon-serotonergic SSRI-effects on HPA-axis activity. Acutedministration of antidepressants causes increases in GRxpression and function, but after chronic treatment ofodents, GR-expression returns to control levels, while basalPA-axis activity is still reduced. Currently, changes inPA-axis activity after chronic treatment with SSRIs arehought to inhibit the multidrug resistance P-glycoprotein.his P-glycoprotein also expels glucocorticoids from cells,o SSRIs might indirectly increase intracellular concentra-ions of glucocorticoids, which can improve GR-functionith increased awakening response as a result. It is of inter-st that this P-glycoprotein inhibition might not occur inreatment resistant patients (Pariante, 2009). Especially theon-responders and/or non-remitters in this study mightave been early refractory patients, who might not havechieved final remission after several successive treatment-teps (Ruhe et al., 2012). Unfortunately these patients wereot followed up routinely to confirm this.

.3. Limitations and strengths

ost importantly, paroxetine treatment was not fullylacebo-controlled, and only patients were followed-up.easuring controls during the same follow-up would haveuantified effects of repeated sampling. A full placebo groupould have differentiated true drug effects from nonspe-ific effects of remission and/or over time. Full placeboreatment was not pursued because of ethical reasons andhe original aim of the study (efficacy of dose-escalation).evertheless, the placebo-controlled dose-escalation phasef this study did not identify dose-related drug-effectsn HPA-axis parameters. Second, although we correctedor awakening-time and age, gender, alcohol-use, smoking,ace, BMI, HDRS17-scores at study-entry in the propensity-

cores, we did not have data to control for potential otheronfounders like menstrual cyclus, late evening/night work-ng hours or childhood adversity. Neither did we instructubjects specifically to sample outside weekend-days (which

Page 9

ol in

R

TO(tDVit

C

N

A

TimfDoDN

A

Sf1

R

A

A

A

A

A

Longitudinal effects of the SSRI paroxetine on salivary cortis

was however mostly done the day before baseline visits dur-ing the week), nor did we quantify or specifically restrictalcohol use the night before sampling. Third, a moreadvanced HPA-axis sampling protocol would have enabled usto additionally detect more subtle changes. We only sampledat one day during the week, while nowadays it is consideredgood practice to base assessment upon measures repeatedon two consecutive weekdays. This could have providedsome measure of trait stability. We neither obtained salivasamples at 15, 45 and 60 min after awakening, nor a diurnalprofile beyond these timepoints, which would have enabledus to determine more complete parameters of the corti-sol awakening curve. Especially 45 min post waking samplesare important for females who peak later than males. Ourrestriction to obtain two cortisol measurements only, mightalso have obscured a difference between patients and con-trols. We did not use objective electronic monitoring or anactimeter to reduce uncertainty of the actual wake andsaliva sampling times. However, despite these limitations,our methods resulted in interesting changes in repeatedcortisol measures that were longitudinally associated withclinical course of depressive symptoms. Fourth, we didnot differentiate other sub-types than melancholic/atypicaldepression. Differentiation of other symptom-axes in MDDmight better corresponds with particular HPA-axis dysregu-lation (Veen et al., 2011; Wardenaar et al., 2011). In futurestudies sub-types should differentiated with the Mood andAnxiety Symptoms Questionnaire (Wardenaar et al., 2011).Fifth, this type of research is susceptible to confoundingby missing data, which also occurred in our sample. How-ever, the main results of this study remained the samewhen we performed multiple imputation (see supplemen-tal). Sixth, the slight different definitions of BCL- andCAR-measurements between studies complicate the discus-sion of comparisons between studies. This urges for uniformnomenclature and standardization of HPA-axis measures.

Major strengths of our study are that (I) we investigatedthe longitudinal effects of SSRI treatment on HPA-axis activ-ity, (II) in patients drug-free at study-entry and (III) treateduniformly according to a study protocol, and (IV) our resultsappeared robust when applying MI to resolve potential biasby missing values (drop-outs and outliers). Altogether, thesestrengths allowed us to longitudinally disentangle antide-pressant and state effects on HPA-axis activity in MDD.

5. Conclusion

This study investigated changes in salivary cortisol over timeduring treatment with paroxetine and a randomized dose-escalation. Without evidence for baseline differences com-pared to controls, we found significant decreases in BCL andAUC in all patients over 12 weeks of paroxetine treatment,suggesting that SSRIs decrease HPA-axis set-point in MDD,which was most prominent in late and non-responders, whileearly responders showed no change. The robust CAR increaseespecially when patients became remitters versus no change

in non-remitters during paroxetine treatment, suggests thatimproved HPA-axis feedback inhibition may result from acombination of overall decreasing cortisol values due to SSRItreatment and additional increased activity of the HPA-axiswhen patients remit from a depressive episode.

B

MDD 269

ole of the funding source

his study was supported by a grant from the Netherlandsrganization for Health Research and Development

ZonMw), program Mental Health, Education of Investiga-ors in Mental Health (OOG; #100-002-002) to Dr. H.G. Ruhé.r. H.G. Ruhé is currently supported by a NWO/ZonMWENI-Grant #016.126.059. The funding source by no means

nfluenced the design or results of the study described inhis manuscript.

onflicts of interest statement

one declared.

cknowledgements

he authors wish to thank the patients who participatedn this study. Mrs. M. Haages managed randomization andaintained blinding. This study was supported by a grant

rom the Netherlands Organization for Health Research andevelopment (ZonMw), program Mental Health, educationf investigators in mental health (OOG; #100-002-002) tor. H.G. Ruhé. Dr. H.G. Ruhé is currently supported by aWO/ZonMW VENI-Grant #016.126.059.

ppendix A. Supplementary data

upplementary data associated with this article can beound, in the online version, at http://dx.doi.org/10.016/j.psyneuen.2014.10.024.

eferences

dam, E.K., Doane, L.D., Zinbarg, R.E., Mineka, S., Craske, M.G.,Griffith, J.W., 2010. Prospective prediction of major depres-sive disorder from cortisol awakening responses in adolescence.Psychoneuroendocrinology 35, 921—931.

dli, M., Baethge, C., Heinz, A., Langlitz, N., Bauer, M., 2005. Isdose escalation of antidepressants a rational strategy after amedium-dose treatment has failed? A systematic review. Eur.Arch. Psychiatry Clin. Neurosci. 255, 387—400.

ihara, M., Ida, I., Yuuki, N., Oshima, A., Kumano, H., Takahashi,K., et al., 2007. HPA axis dysfunction in unmedicated majordepressive disorder and its normalization by pharmacotherapycorrelates with alteration of neural activity in prefrontal cortexand limbic/paralimbic regions. Psychiatry Res. 155, 245—256.

ppelhof, B.C., Huyser, J., Verweij, M., Brouwer, J.P., Van Dyck,R., Fliers, E., et al., 2006. Glucocorticoids and relapse ofmajor depression (dexamethasone/corticotropin-releasing hor-mone test in relation to relapse of major depression). Biol.Psychiatry 59, 696—701.

ubry, J.M., Jermann, F., Gex-Fabry, M., Bockhorn, L., Van der Lin-den, M., Gervasoni, N., et al., 2010. The cortisol awakeningresponse in patients remitted from depression. J. Psychiatr. Res.44, 1199—1204.

artak, A., Spreeuwenberg, M.D., Andrea, H., Busschbach, J.J.V.,Croon, M.A., Verheul, R., et al., 2009. The use of propensityscore methods in psychotherapy research. Psychother. Psycho-som. 78, 26—34.

Page 10

2

B

B

B

B

B

C

C

D

D

E

F

G

H

H

H

H

H

H

J

K

K

K

L

L

L

L

N

P

P

R

R

R

R

S

S

70

hagwagar, Z., Hafizi, S., Cowen, P.J., 2003. Increase in concen-tration of waking salivary cortisol in recovered patients withdepression. Am. J. Psychiatry 160, 1890—1891.

hagwagar, Z., Hafizi, S., Cowen, P.J., 2005. Increased salivarycortisol after waking in depression. Psychopharmacology (Berl.)182, 54—57.

ockting, C.L., Lok, A., Visser, I., Assies, J., Koeter, M.W., Schene,A.H., 2012. Lower cortisol levels predict recurrence in remittedpatients with recurrent depression: a 5.5 year prospective study.Psychiatry Res. 200, 281—287.

schor, T., Ising, M., Erbe, S., Winkelmann, P., Ritter, D., Uhr, M.,et al., 2012. Impact of citalopram on the HPA system. A study ofthe combined DEX/CRH test in 30 unipolar depressed patients.J. Psychiatr. Res. 46, 111—117.

uhl, E.S., Jensen, T.K., Jessen, N., Elfving, B., Buhl, C.S.,Kristiansen, S.B., et al., 2010. Treatment with an SSRIantidepressant restores hippocampo-hypothalamic corticoste-roid feedback and reverses insulin resistance in low-birth-weightrats. Am. J. Physiol. Endocrinol. Metab. 298, E920—E929.

hida, Y., Steptoe, A., 2009. Cortisol awakening response and psy-chosocial factors: a systematic review and meta-analysis. Biol.Psychol. 80, 265—278.

low, A., Thorn, L., Evans, P., Hucklebridge, F., 2004. The awak-ening cortisol response: methodological issues and significance.Stress 7, 29—37.

e Bellis, M.D., Gold, P.W., Geracioti Jr., T.D., Listwak, S.J., Kling,M.A., 1993. Association of fluoxetine treatment with reductionsin CSF concentrations of corticotropin-releasing hormone andarginine vasopressin in patients with major depression. Am. J.Psychiatry 150, 656—657.

euschle, M., Hamann, B., Meichel, C., Krumm, B., Lederbo-gen, F., Kniest, A., et al., 2003. Antidepressive treatment withamitriptyline and paroxetine: effects on saliva cortisol concen-trations. J. Clin. Psychopharmacol. 23, 201—205.

vans, P., Fredhoi, C., Loveday, C., Hucklebridge, F., Aitchison, E.,Forte, D., Clow, A., 2011. The diurnal cortisol cycle and cogni-tive performance in the healthy old. Int. J. Psychophysiol. 79,371—377.

ries, E., Dettenborn, L., Kirschbaum, C., 2009. The cortisolawakening response (CAR): facts and future directions. Int. J.Psychophysiol. 72, 67—73.

allagher, P., Leitch, M.M., Massey, A.E., lister-Williams, R.H.,Young, A.H., 2006. Assessing cortisol and dehydroepiandros-terone (DHEA) in saliva: effects of collection method. J.Psychopharmacol. 20, 643—649.

ajat, A., Diez-Roux, A., Franklin, T.G., Seeman, T., Shrager,S., Ranjit, N., et al., 2010. Socioeconomic and race/ethnicdifferences in daily salivary cortisol profiles: the multi-ethnic study of atherosclerosis. Psychoneuroendocrinology 35,932—943.

ardeveld, F., Spijker, J., Vreeburg, S.A., Graaf, R., Hendriks,S.M., Licht, C.M., Nolen, W.A., Penninx, B.W., Beekman, A.T.,2014. Increased cortisol awakening response was associated withtime to recurrence of major depressive disorder. Psychoneu-roendocrinology 50C, 62—71, http://dx.doi.org/10.1016/j.psyneuen.2014.07.027.

armer, C.J., Bhagwagar, Z., Shelley, N., Cowen, P.J., 2003. Con-trasting effects of citalopram and reboxetine on waking salivarycortisol. Psychopharmacology (Berl.) 167, 112—114.

euser, I., Yassouridis, A., Holsboer, F., 1994. The combined dex-amethasone/CRH test: a refined laboratory test for psychiatricdisorders. J. Psychiatr. Res. 28, 341—356.

olsboer, F., 2000. The corticosteroid receptor hypothesis of depres-sion. Neuropsychopharmacology 23, 477—501.

uber, T.J., Issa, K., Schik, G., Wolf, O.T., 2006. The corti-sol awakening response is blunted in psychotherapy inpa-tients suffering from depression. Psychoneuroendocrinology 31,900—904.

S

H.G. Ruhé et al.

aeger, T.F., 2008. Categorical data analysis: away from ANOVAs(transformation or not) and towards logit mixed models. J. Mem.Lang. 59, 434—446.

irschbaum, C., Hellhammer, D.H., 1994. Salivary cortisol inpsychoneuroendocrine research: recent developments andapplications. Psychoneuroendocrinology 19, 313—333.

udielka, B.M., Hellhammer, D.H., Wust, S., 2009. Why do werespond so differently? Reviewing determinants of human sali-vary cortisol responses to challenge. Psychoneuroendocrinology34, 2—18.

unugi, H., Hori, H., Adachi, N., Numakawa, T., 2010. Interfacebetween hypothalamic-pituitary-adrenal axis and brain-derivedneurotrophic factor in depression. Psychiatry Clin. Neurosci. 64,447—459.

amers, F., Vogelzangs, N., Merikangas, K.R., de, J.P., Beekman,A.T., Penninx, B.W., 2013. Evidence for a differential roleof HPA-axis function, inflammation and metabolic syndromein melancholic versus atypical depression. Mol. Psychiatry 18,692—699.

aw, R., Hucklebridge, F., Thorn, L., Evans, P., Clow, A., 2013.State variation in the cortisol awakening response. Stress 16,483—492.

enze, E.J., Mantella, R.C., Shi, P., Goate, A.M., Nowotny, P., But-ters, M.A., et al., 2010. Elevated cortisol in older adults withgeneralized anxiety disorder is reduced by treatment: a placebo-controlled evaluation of escitalopram. Am. J. Geriatr. Psychiatry19, 482—490.

ok, A., Mocking, R.J., Ruhe, H.G., Visser, I., Koeter, M.W., Assies,J., et al., 2011. Longitudinal hypothalamic-pituitary-adrenalaxis trait and state effects in recurrent depression. Psychoneu-roendocrinology 37, 892—902.

ikisch, G., Mathe, A.A., Czernik, A., Thiele, J., Bohner, J., Eap,C.B., et al., 2005. Long-term citalopram administration reducesresponsiveness of HPA axis in patients with major depression:relationship with S-citalopram concentrations in plasma andcerebrospinal fluid (CSF) and clinical response. Psychopharma-cology (Berl.) 181, 751—760.

ariante, C.M., 2009. Risk factors for development of depressionand psychosis. Glucocorticoid receptors and pituitary implica-tions for treatment with antidepressant and glucocorticoids.Ann. N. Y. Acad. Sci. 1179, 144—152.

ruessner, M., Hellhammer, D.H., Pruessner, J.C., Lupien, S.J.,2003. Self-reported depressive symptoms and stress levels inhealthy young men: associations with the cortisol response toawakening. Psychosom. Med. 65, 92—99.

osenbaum, P.R., Rubin, D.B., 1983. The central role of the propen-sity score in observational studies for causal effects. Biometrika70, 41—55.

uhe, H.G., Booij, J., Weert, H.C., Reitsma, J.B., Franssen, E.J.,Michel, M.C., et al., 2009. Evidence why paroxetine dose escala-tion is not effective in major depressive disorder: a randomizedcontrolled trial with assessment of serotonin transporter occu-pancy. Neuropsychopharmacology 34, 999—1010.

uhe, H.G., Huyser, J., Swinkels, J.A., Schene, A.H., 2006. Doseescalation for insufficient response to standard-dose selectiveserotonin reuptake inhibitors in major depressive disorder: sys-tematic review. Br. J. Psychiatry 189, 309—316.

uhe, H.G., van, R.G., Spijker, J., Peeters, F.P., Schene, A.H., 2012.Staging methods for treatment resistant depression. A system-atic review. J. Affect. Disord. 137, 35—45.

chule, C., 2007. Neuroendocrinological mechanisms of actions ofantidepressant drugs. J. Neuroendocrinol. 19, 213—226.

helton, R.C., 2007. The molecular neurobiology of depression.Psychiatr. Clin. North Am. 30, 1—11.

talder, T., Hucklebridge, F., Evans, P., Clow, A., 2009. Use of a

single case study design to examine state variation in the cor-tisol awakening response: relationship with time of awakening.Psychoneuroendocrinology 34, 607—614.

Page 11

ol in

V

V

W

W

Longitudinal effects of the SSRI paroxetine on salivary cortis

Stetler, C., Miller, G.E., 2011. Depression and hypothalamic-pituitary-adrenal activation: a quantitative summary of fourdecades of research. Psychosom. Med. 73, 114—126.

Stetler, C., Miller, G.E., 2005. Blunted cortisol response to awak-ening in mild to moderate depression: regulatory influences ofsleep patterns and social contacts. J. Abnorm. Psychol. 114,697—705.

Thorn, L., Evans, P., Cannon, A., Hucklebridge, F., Clow, A., 2011.Seasonal differences in the diurnal pattern of cortisol secretionin healthy participants and those with self-assessed seasonalaffective disorder. Psychoneuroendocrinology 36, 816—823.

Veen, G., van Vliet, I.M., Derijk, R.H., Giltay, E.J., van, P.J., Zitman,F.G., 2011. Basal cortisol levels in relation to dimensions andDSM-IV categories of depression and anxiety. Psychiatry Res. 185,121—128.

Vermetten, E., Vythilingam, M., Schmahl, C.D.E.K.C., Southwick,S.M., Charney, D.S., et al., 2006. Alterations in stress reactivity

after long-term treatment with paroxetine in women with post-traumatic stress disorder. Ann. N. Y. Acad. Sci. 1071, 184—202.

Vreeburg, S.A., Hartman, C.A., Hoogendijk, W.J., van, D.R., Zit-man, F.G., Ormel, J., et al., 2010. Parental history of depression

W

MDD 271

or anxiety and the cortisol awakening response. Br. J. Psychiatry197, 180—185.

reeburg, S.A., Hoogendijk, W.J., van, P.J., Derijk, R.H., Verha-gen, J.C., van, D.R., et al., 2009. Major depressive disorder andhypothalamic-pituitary-adrenal axis activity: results from a largecohort study. Arch. Gen. Psychiatry 66, 617—626.

rshek-Schallhorn, S., Doane, L.D., Mineka, S., Zinbarg, R.E.,Craske, M.G., Adam, E.K., 2013. The cortisol awakeningresponse predicts major depression: predictive stability over a4-year follow-up and effect of depression history. Psychol. Med.43, 483—493.

ardenaar, K.J., Vreeburg, S.A., van, V.T., Giltay, E.J., Veen, G.,Penninx, B.W., et al., 2011. Dimensions of depression and anxi-ety and the hypothalamo-pituitary-adrenal axis. Biol. Psychiatry69, 366—373.

estermann, J., Demir, A., Herbst, V., 2004. Determination of cor-tisol in saliva and serum by a luminescence-enhanced enzyme

immunoassay. Clin. Lab. 50, 11—24.

ust, S., Wolf, J., Hellhammer, D.H., Federenko, I., Schommer, N.,Kirschbaum, C., 2000. The cortisol awakening response — normalvalues and confounds. Noise Health 2, 79—88.