PergamonS0005-7967(96)00068-XCopyright© 1997ElsevierScienceLtd.Printed in Great Britain. All rightsreserved0005-7967/97$17.00+ 0.00 Behav. Res. Ther.Vol.35, No. I, pp. 79-89, 1997PSYCHOMETRIC PROPERTIES OF THE DEPRESSIONANXIETY STRESS SCALES (DASS) IN CLINICALSAMPLES*T I M O T H Y A. B R O W N , I.# B R U C E F. C H O R P I T A , W I L L I A M K O R O T I T S C W and D A V I D H. B A R L O W ~Center for Anxiety and Related Disorders, Boston University, 648 Beacon Street, Boston, MA 02215,U.S.A. and 2Universityof North Carolina at Greensboro, Greensboro, NC, U.S.A.(Received 9 April 1996; revised 17 July 1996)SummaryThe psychometric properties of the Depression Anxiety Stress Scales (DASS) were evaluatedin two studies using large clinical samples (N = 437 and N = 241). In Study 1, the three scales comprising the DASS were shown to have excellent internal consistency and temporal stability. An exploratoryfactor analysis (principal components extraction with varimax rotation) yielded a solution that washighly consistent with the factor structure previously found in nonclinical samples. Between-groupscomparisons indicated that the DASS distinguished various anxiety and mood disorder groups in thepredicted direction. In Study 2, the conceptual and empirical latent structure of the DASS was upheldby findings from confirmatory factor analysis. Correlations between the DASS and other questionnaireand clinical rating measures of anxiety, depression, and negative affect demonstrated the convergentand discriminant validity of the scales. In addition to supporting the psychometric properties of theDASS in clinical anxiety and mood disorders samples, the results are discussed in the context of currentconceptualizations of the distinctive and overlapping features of anxiety and depression. Copyright ©1997 Elsevier Science LtdI N T R O D U C T I O NAnxiety and depression have been typically regarded by researchers to be distinct at the conceptual level. Nevertheless, attempts to quantify these constructs using questionnaires and clinicalratings have often demonstrated a high degree of overlap (intercorrelation) between measures ofanxiety and depression (cf. Clark & Watson, 1991a). Such findings have led investigators toquestion whether clinical anxiety and depression are indeed empirically distinct phenomena andto explore the possibility that the considerable overlap evidenced by these measures reflects poordiscriminant validity of these domains (e.g. anxiety and depression as different points on thesame continuum or variations in the expression of a broader underlying disorder; Barlow, 1991;Barlow, Chorpita & Turkovsky, 1996). At the syndrome level, the high rates of comorbidityamong the anxiety and m o o d disorders have also added to the debate on the distinguishabilityof these constructs (Andrews, 1996; Brown, 1996; Brown & Barlow, 1992).Based on their review of this extensive literature, Clark and Watson (1991b) concluded thatalthough anxiety and depression share a significant nonspecific component encompassing generalaffective distress and other c o m m o n symptoms, the two constructs can be distinguished by certain unique features. Specifically, Clark and Watson have proposed a tripartite structure ofanxiety and depression consisting of general distress or negative affect (shared by anxiety anddepression), physiological hyperarousal (specific to anxiety), and an absence of positive affect(specific to depression). In a separate research program spanning from 1979 to 1990, S.H.Lovibond and P.F. Lovibond (Lovibond & Lovibond, 1993; Lovibond, 1983) conducted psychometric evaluations of a questionnaire that they developed to assess the full range of core symp-*Portions of this paper were presented at the meeting of the Association for Advancement of Behavior Therapy, SanDiego, CA, November 1994.tAuthor for correspondence.7980 TimothyA. Brownet al.toms of anxiety and depression while providing maximum discrimination between the scales ofanxiety and depression. Although the authors intended to develop a measure consisting of twoscales (i.e. anxiety and depression), a third factor emerged from their analyses of scale structureconsisting of items relating to difficulty relaxing, irritability, and agitation. Accordingly, theresulting three scales (consisting of 14 items each) were named the Depression Anxiety StressScales (DASS). Psychometric analyses of the DASS, conducted primarily with nonclinicalsamples, have provided strong support for the internal consistency and convergent and discriminant validity of the three scales (Lovibond & Lovibond, 1995). Exploratory and confirmatoryfactor analyses of the DASS items have consistently reproduced the three-factor structure inlarge nonclinical samples (Lovibond & Lovibond, 1995). Although the DASS was developedprior to Clark and Watsons model of anxiety and depression, the three psychometrically distinct DASS factors could be viewed as consistent with the three components of the tripartitemodel: DASS-Depression: characterized by low positive affect, loss of self-esteem and incentive,and a sense of hopelessness (absence of positive affect); DASS-Anxiety: characterized by autonomic arousal and fearfulness (physiological hyperarousal); and DASS-Stress: characterized bypersistent tension, irritability, and a low threshold for becoming upset or frustrated (negativeaffect). In addition to this possible parallel with the tripartite model, we have observed that theDASS-Stress scale appears to evaluate symptoms corresponding to those associated with generalized anxiety disorder (GAD; e.g. irritability, muscle tension, feeling keyed up/on edge).Findings suggesting that these symptoms which distinguish GAD from other anxiety disorderscontributed strongly to the decision to reformulate the associated symptom criterion of GAD inDSM-IV (Brown, Barlow & Liebowitz, 1994; Brown, Marten & Barlow, 1995; Marten, Brown,Barlow, Borkovec, Shear & Lydiard, 1993).Although the existing data provide strong support for the psychometric and conceptual basisof the DASS, most of this research has been conducted using nonpatient samples (Lovibond &Lovibond, 1995). Hence, the purpose of the present studies was to examine the psychometricproperties of the DASS in large clinical samples. The first study examined the reliability(internal consistency, temporal stability), factor structure, and the discriminability of the DASSin a large clinical sample (N = 437). In a second study using an independent clinical sample(N = 241), the psychometric properties of the scales were further evaluated with confirmatoryfacto
r analysis of the DASS latent structure and correlational analyses of convergent and discriminant validity.STUDY 1M e t h o dParticipants. Participants were 437 patients presenting for assessment and treatment at thePhobia and Anxiety Disorders Clinic, Center for Stress and Anxiety Disorders. Women constituted the larger portion of the sample (63.6%); the average age of the sample was 36.10 yr(SD = 10.55, range = 18-65). Diagnoses were established with the Anxiety Disorders InterviewSchedule-Revised (ADIS-R; Di Nardo & Barlow, 1988), a structured interview designed to comprehensively evaluate the DSM-III-R (American Psychiatric Association, 1987) anxiety andmood disorders as well as screen for the presence of other major disorders (e.g. somatoform,psychotic). Conservative estimates of interrater agreement using the ADIS-R for principalDSM-III-R disorders (i.e. calculated on the basis of two independent interviews) range frommoderate to excellent (Di Nardo, Moras, Barlow, Rapee & Brown, 1993). In instances wherethe patient was deemed as meeting criteria for two or more diagnoses, the principal diagnosiswas the one that received the highest ADIS-R clinical severity rating (0-8 scale) that indicatedthe diagnosticians judgment of the degree of distress and interference in functioning associatedwith the diagnosis. Patients DSM-III-R principal diagnoses were as follows: panic disorder withor without agoraphobia (n = 150); GAD (n = 64); social phobia (n = 59); simple phobia(n = 20); obsessive-compulsive disorder (OCD) (n = 20); mood disorder (collapsing acrossmajor depressive disorder and dysthymic disorder; n = 35); other (e.g. posttraumatic stress disorder, anxiety or depressive disorder NOS, coprincipal diagnoses; n = 89).Depression AnxietyStress ScalesTable 1. Reliabilityof the DASS: internal consistency(Cronbachs alpha)81 DASS-Depression0.960.960.950.950.910.960.94DASS-Anxiety0.890.890.890.890.880.880.88DASS-Stress0.930.930.940.940.940.880.89Entire sample (N = 437)PD/A (n = 150)GAD (n = 64)SOC (n = 59)SIM (n = 20)OCD (n = 20)MOOD (n = 35) Note: PD/A = panic disorder with or without agoraphobia; GAD = generalizedanxiety disorder; SOC = social phobia;SIM = simple phobia; OCD = obsessive-compulsivedisorder; MOOD = mood disorder (major depression, dysthymia).Measures. As noted earlier, the DASS is a 42-item instrument measuring current (over thepast week) symptoms of depression, anxiety, and stress. Each of the three scales consists of 14items which are responded to using a 0-3 scale, where 0 = did not apply to me at all, and3 = applied to me very much, or most of the time (range of possible scores for each scale is 0-42). Further details on the directions, items, and scoring of the DASS are presented in Lovibondand Lovibond (1995).*Procedure. Following the ADIS-R, patients completed a questionnaire battery that includedthe DASS. In order to evaluate the test-retest reliability of the DASS, 20 patients were randomly selected to be re-administered the DASS 2 weeks following their intake evaluation (seeResults for the diagnostic breakdown of the temporal stability sample).ResultsReliability. The internal consistency of the DASS was calculated for the entire sample(N = 437) and for each principal diagnosis group. As seen in Table 1, the internal consistency(i.e. Cronbachs alpha) of each scale of the DASS was quite favorable, both for the entiresample (~ = 0.96, 0.89 and 0.93 for Depression, Anxiety, and Stress, respectively) and withineach diagnostic group (range of as = 0.88-0.96). As noted above, 20 patients were re-administered the DASS 2 weeks following their initial intake evaluation. These patients had the following principal diagnoses: panic disorder (n = 7), G A D (n = 4), major depression (n = 4), socialphobia (n = 2), simple phobia (n = 2), OCD (n = 1). As shown in Table 2, test-retest correlations indicated that all three scales evidenced favorable temporal stability (range of rs = 0.71-0.81). Because test-retest correlations would fail to detect any systematic increase or decrease inscores over time, paired t-tests were conducted as another test of temporal stability. These ttests were nonsignificant for all three DASS scales (Table 2).Factor structure. Because the factor structure of the DASS has been examined using nonclinical participants in prior studies (Lovibond & Lovibond, 1995), exploratory factor analysis wasused to examine the structure of the scale in a clinical sample. Using the entire study sample(N = 437), principal components extraction with varimax rotation was performed (orthogonalrotation was used to assist in the interpretation and description of the resulting factor loadings).Selection of the number of factors to be rotated was based on conjunctive criteria requiring: (a)the eigenvalue of the factor to be greater than 1; and (b) the use of the scree test (Cattell, 1966).These criteria indicated a three-factor solution that accounted for 55% of the item variance(eigenvalues = 16.64, 3.96 and 2.53). Factor loadings for the 42 items are presented in Table 3.The first factor, Depression, reproduced the DASS-Depression scale exactly (i.e. the 14 itemscomprising the DASS-Depression scale were the only items to load on this factor). The range offactor loadings (after varimax rotation) was 0.83-0.59; there were no double-loading items(double-loading was operationalized as secondary loadings of 0.40 or greater). The second factor, Stress, reproduced the DASS-Stress scale exactly with the exception of one item. The first14 items to load on this factor corresponded to the 14 items of the DASS-Stress scale (range offactor loadings = 0.76-0.51); one of these items also loaded on the Anxiety factor (factor load-*To obtain copies of the instrument and manual, contact P.F. Lovibond, School of Psychology, University of NewSouth Wales, Sydney,NSW 2052, Australia.82 Timothy A. Brown et al.Table 2. Reliability of the DASS: temporal stability (2-week; n = 20) Time 1Time 2M10.65SD9.30M11.35SD9.25r0.713** tDASS-Depression -0.45DASS-Anxiety 10.90 8.12 11.35 9.06 0.785*** -0.35DASS-Stress 21.10 11.15 19.40 12.45 0.813?** 1.04***P all groups4 all groups4 1,3,44 S>AA> S> AS>D, AD >A, SS> D, AD >S>A0.090.490.18A> D, S-0.010.040.17S>D, A Note: PANAS = Positiveand NegativeAffectScales;ADIS-IV-L= AnxietyDisorders InterviewSchedule for DSM-IV:Lifetime Version; DEP = depression (major depression or dysthymia);PD = panic disorder with or without agoraphobia; GAD = generalizedanxietydisorder.Correlations of 0.18 or greater are significant at P D, A = DASS-Stress scale is more strongly (P