5- comorbidity of unipolar depression ii. comorbidity

7/28/2019 5- Comorbidity of Unipolar Depression II. Comorbidity

1/9

J ou r na l of A b n o r m a l Psychology1991, Vol. 100, No. 2, 214-222 Copyr ight 1991 by the A m e r i can Psychological Association, Inc.0021-843X/91/S3.00

Comorbidity of Unipolar Depression: II. ComorbidityWith Other Mental Disorders in Adolescents and Adults

Paul Rohde, Peter M. Lewinsohn, and John R. SeeleyOregon Research Institute, E ugene, OregonThe current and lifetime comorbidity of depressive (i.e., major depressive disorder and dysthymia)with other comm on me ntal disorders w as examined in com mu nity samples of older adolescents( n - 1,710) an d adults ( = 2,060). Current an d lifetime histories of depression in the adolescentswere highly comorbid w ith several other m ental disorders. Th e adults had a lower but statisticallysignificant degree of comorbidity, primarily with substance use disorder. Depression in bothgroups was more likely to occur after the other disorder rather tha n to precede it. Com orbidity didno t affect the duration or severity of depression. Com orbidity in the adolescents was associatedwith greater frequency of suicidal behav ior and treatm ent seeking. The findings suggest that early-onset depression is associated with a greater degree of comorbidity and may represent a moreserious form of the disorder.

In this article, which is the second in a series on the como r-bidity of unipolar depression, w e exam ine the degree to whichunip olar depression (i.e., m ajor depression and dysthym ia) iscomorbid with other psychiatric disorders in adult an d adoles-cent community samples. To the extent that depression is co-morbid with specific disorders, the temporal order of the twodisorders (i.e., does depression more often precede the disorderor vice versa?) and the impact of the presence of the seconddisorder on the p heno men ology of depression (e.g., age at onsetof first depression and duration and severity of depressive epi-sodes) are described.Prevalence of ComorbidityThe comorbidity of depression with other psychiatric dis-orders is a rather recent area of investigation; however, researchhas suggested th at many, perhap s even mo st, persons wh o expe-rience depression have at least on e comorbid psychiatric dis-order at some point in their life. Although em pirical evidence isstill being gath ered, a survey of the current literature indicatesthat depression is thought to be comorbid with a number ofmental disorders, w hich include anxiety disorders (Leck man,Weissman, Merikangas, Pauls, & PrusofF, 1983; M aser & Clon-inger, 1990; Regier, B urke, & Burk e, 1990), substance abuse(Weissman, Myers, & Harding, 1980; W inok u r , Black, &Nasrallah, 1988), conduct disorder in child patients (Kovacs,

Paulauskas, Gatsonis, & Richards, 1988), an d somatic disorders(Cadoret, Widmer, & Troughton, 1980; Katon, Kleinman, &Rosen, 1982).

Preparatio n of this article wa s supported in part by N ational Insti-tu te of Mental Heal th Grants MH33572, AG1449, MH35672, andMH40501.We gratefully acknowledge the assistance of the three anonymousreviewers for their comments on a draft of this article.Correspondence con cern ing this article should be addressed to PaulRohde, Oregon Research Institute, 1715 Frank l in Boulevard, Eugene,Oregon 97 403-1983.

Of the various psychiatric disorders, the comorbidity of de-pression with anxiety disorders ha s received the most researchattention. Consistent evidence for the co-occurrence of depres-sion and an xiety disorders has been reported in num erous com-munity (e.g., Angst & Dob ler-Mikola, 1985; Ang st, V ollrath,Merikangas, & E rnst, 1990; Boyd et al, 1984; Kashani et al.,1987; Murphy, Sobol, Neff, Olivier, & Leighton, 1984) and pa-tient samples (e.g., B arlow, DiNardo, Verm ilyea, V ermilyea, &Blanchard, 1986; Dealy, I sh ik i , Avery, Wilson , & Dunner ,1981).Most research stu dies have focused on ma jor depression. Animp ortant exception is the w ork of W eissman, Leaf, Bruce, andFlorio (1988). Using data from the large community-based Epi-demiologic Catch ment Area (ECA ) studies, W eissman et al. ex-amined th e degree of comorbidity between dysthymia an dother psych iatric disorders. The m ajority (77.1%) of those per-sons with a lifetime diagnosis of dysthymia also had an addi-tional lifetime disorder (most comm only major depression, anx -iety, substance abuse, and bipolar disorders) according to Diag-nostic and Statistical Manual of Mental Disorders (3rd ed.;DSM-III; American Psychiatric Association, 1980) criteria.The fact that fewer than one quarter of the persons were puredysthym ics led the researchers to qu estion the utility of dysthy-mia as a separate diagnostic entity. Elevated rates of comorbi-dity for dysthymia were a lso reported in other community(Weissman & M yers, 1978) and patient sam ples (Keller & Sha-piro, 1982; Klein, Taylor, Harding, & Dickstein, 1988; Mez-zich, Ah n, F ebrega, & Pilkonis, 1990).

Temporal Order of DisordersGiven that depression is como rbid w ith another disorder, theextent to which the comorbid disorder is more likely to precedeor to follow the depressive episode is im port ant for the reasonsmentioned earlier.When the temporal order of comorbid depressive and anxi-ety disorders has been examined, anxiety disorders generallyhave been found more often to precede rather th an to follow the

214


2/9

CO MO RBI DI TY O F DEPRESSION 21 5depression (e.g., Alloy, Kelly, Mineka , & Clements, 1990; Angstet al., 1990). H owever, this tempo ral o rdering has not been con-sistently n oted (e.g., Breier, Charney, & Heninger, 1984,1985).Alloy et al. suggested tha t such predom inant tempo ral orderingmay correspond to the m ann er in w hich persons respond tomajor life stressors; one's first response is characterized by anxi-ety and agitation, followed by despair and depression(Bowlby,1960; Seligman, 1975).

Impact of Comorbid Disorders on DepressionComorbidity may effect the onset age, presentation, course,and conseq uences of the depressive episode. These effects maybe universal across all psychiatric disorders or differ for specificdisorders. A s may be expected w hen one assumes that havingtw o disorders is worse than having one, the impact of the pres-ence of a comorbid disorder on depression h as often been nega-tive. Gersh and Fowles (1979) reviewed several investigationsthat examined the degree of comorbidity between an xiety anddepression. T hey concluded that p atients in w hom depression

and anx iety are comorbid are characterized by an earlier onsetage, a mo re chronic course, greater likelihood of relapse, poorerresponse to antidepressant treatment, an d stronger suicidaltendencies. Similarly, Keller and colleagues (Keller et al., 1984;Keller, Lavori, Lewis, & Klerman, 1983) have found that thepresence of a como rbid disorder in patients w ith major depres-sion w as associated w ith longer episode duration . O ther investi-gators have also reported that depressed persons w ith a comor-bid psychiatric disorder are more likely to have suicidal ide-ation and a yo unger onset age (Andreasen & W inokur, 1979;Winokur et al., 1988). Hirschfeld, Hasin, K eller, E ndicott, andW unde r (1990) com pared pure depressed patients with de-pressed pa tients w ith conc urrent alcoholism. The comorbid de -pressed persons differed on several demographic characteris-tics. They w ere older, less likely to be m arried, and more likelyto be men; they also had significantly lower ratings of globaladjustment at follow-up. How ever, they did not have a signifi-cantly longer episode duration, nor were they more likely torelapse once recovered. In related research, also w ith patientsamples, Kupfer and Carpenter (1990) reported that althoughthe presence of a comorbid alcoholism increased th e t imeneeded for recovery from an episode of recurrent major depres-sion, the comorbid an d pur e depressed persons w ere equallylikely to recover from the depression within the follow-up pe -riod of the study.Present Study

As part of this series of analyses to examine the extent towhich psychiatric disorders are comorbid in community sam-ples, w e reported the current and lifetime comorbidity betweenmajor depression an d dysthymia in large com mu nity samplesof adolescents and adults (Lewinsohn, Rohde, Seeley, & Hops,1991). To briefly sum ma rize those results, the two depressivedisorders were significantly but not completely comorbid. M ostdepressed persons (approximately 80%) experienced only anepisode of major depression, 10% experienced only dysthymia,an d 10% experienced both disorders. W hen the two disorderswere comorbid, dysthymia was most likely to precede major

depression, especially when the onset age was less than 21. Inmany respects the three depressed groups (i.e., pure major de-pression, pu re dysthym ia, and com orbid major depression anddysthymia) were no t significantly different from each other. O fgreatest relevance to our research w as the finding that personswithin the three group s did not differ in their rates of comor-bidity w ith other psychiatric disorders. Therefore, w e felt justi-fied in forming one grou p of depressed persons and exam iningthe com orbidity of unipolar depression w ith other psychiatricdisorders.Extensive diagnostic data are available from four large com-munity-based samples of older adolescents and adults. The agerange, sample size, and composition of the samples as well asthe use of comprehensive and reliable diagnostic proceduresprovided us wi th the opportuni ty to examine the rates ofcurrent comorbidity (i.e., simultaneous co-occurrence of twodisorders) and lifetime comorbidity (i.e., degree to which per-sons with a lifetime history of one disorder are likely to haveexperienced anothe r disorder) of depression w ith various men -tal disorders that occurred w ith sufficient frequency in the sam-ples. Given tha t depressed persons have been found to be at anelevated risk for hav ing a p articula r psychiatric disorder or acluster of them , we were interested in the tem poral order of thetw o disorders and whether the presence of the comorbid dis-order significantly affected the age at onset, course, or presenta-tion of the depressive episode.

MethodParticipants

The subjects for this study were selected from two data sets thatcomprised large samples of adolescents and adults, w hich were de-scribed in detail in Lewinsohn et al. (1991). Briefly, the adolescentsample consisted of 1,710 older adolescents (ages 14-18) who had com-pleted a quest ionnaire an d participated in a diagnostic interview (ad-ditional details about this sample w ere provided in Lew insohn, Hops,Roberts, & Seeley, 1988). The adult sample consisted of 2,060 partici-pants w ho were a subset selected fo r diagnostic interview from threeseparate longitu dinal studies (Studies 1 , 2, and 3) in which 6,742 com-munity residents participated by com pleting an extensive qu estion-naire. Written informed consent was obtained from all participantsan d from parents of the adolescents.

Assessment of Depression and Other Mental DisordersDiagnoses of all current an d past episodes of depression an d othermental disorders were based on info rma tion gathered in stand ardized

semistructured interviews. Diagnoses according to the revised D S M -III (DSM-1II-R; American Psychiatric Association, 1987) in the ado-lescent sample were based on inform ation obtained w ith a m odifiedform of the Schedule fo r Affective Disorders an d Schizophrenia forSchool-Aged Children that combined the Epidemiologic (Orvaschel,Puig-Antich, Chambers, & Johnson, 1982) and the Present Episodeversions.Information in the adu lt samples was gathered w ith the Schedule forAffective Disorders an d Schizophrenia-Lifetime version (Endicott &Spitzer, 1978), and diagnoses were based on criteria provided by theResearch D iagnost ic Cri ter ia (RD C; Spitzer , E ndicot t , & Ro bins,1978,1985). As described in Lewinsohn et al. (1991), the majori ty ofadults original ly diagnosed w ith RD C in termit tent depression or


3/9

216 P. R O H D E , P. LEWI NSO HN, AND J. SEELEYmin or depression of at least 2-years duration w ere reclassified as hav-ing experienced dysthym ia in DSM-HI-R terms.The adults also completed the Center for Epidemiological StudiesDepression Scale (CES-D; Radloff, 1977). The CES-D, which was spe-cifically designed for use with general comm unity samples, is a self-re-port m easure of the frequency of 20 depressive symptom s durin g theprevious week . It was used in the research reported herein as a measureof the cu rrent severity of depression.Diagnostic Classification

Although the RDC was a forerunner of the DSM-IIf-R, and the twodiagnostic systems share man y similarities, several important differ-ences need to be noted. T he diagnosis of major depression in the RD C,although similar to the DSM-III-R, is somew hat m ore stringent (seeLewinsohn et al., 1991, fo r more details). In the RDC the occurrence ofpanic, phobic, or obsessive-compulsive disorders ca nno t be limited intime to an episode of major depressive disorder; that is, if the personexperiences the sym ptom s of anxiety only durin g the depressive epi-sode, only the depressive episode is diagnosed. This restriction is notmade in the DSM-III-R, and a person can receive concurrent diag-noses. In b oth systems a diagnosis of generalized anxiety disorder canbe made in the presence of depression, if the anxiety symptoms areclearly dist inguished from the other disorder. In conclusion, as com-pared with the RDC, the possibility of the concurrent occurrence ofdepression and anxie ty disorders is greater with DSM-III-R diag-noses.Because of the relatively lo w frequency of occurrence, w e combinedth e categories of abuse an d dependence of various psychoactivesub-stances (including alcoh ol) to create a single category labeled substanceus e disorders. Similarly, w e comb ined panic, phobic, obsessive-com-pulsive, and generalized anxiety disorders to form a cluster labeledanxiety disorders. For the adolescents, separation anxiety and over-anx ious disorders, tw o anx iety disorders of chi ldhood and adoles-cence, were included in the cluster of anxiety disorders. Condu ct an doppositional-defiant disorders in the adolescents w ere com bined intoa category labeled disruptive behavior disorders.

On the basis of diagnost ic inform ation, four groups w ere formed fo rth e analyses: (a) persons with one or more lifetime episodes of depres-sion and no other psyc hiatric disorders (pure depressed); (b) personswith no lifetime episodes of depression but one or more episodes ofanother psych iatric disorder (pure other); (c ) persons who had experi-enced episodes of both depression and anoth er psychiatric disorder atsome point during their life (comorbid); and (d) persons with no re-ported episodes of any psyc hiatric disorder (never m enta lly ill).Assessment of Treatm ent Seeking, SuicidalIdeation, an d Suicide Attempts

Treatment fo r depression w as denned as receiving outpatient psycho-therapy or counseling , being prescribed an tidepressant med ications orl i thium, being hospitalized, or receiving electroshock therapy du ring adepressive episode. Treatment for other mental disorders w as defined aspsychotherapy, counseling , medications, or hospitalization for an y dis-order other than depression . Dur ing the diagnostic interv iew the ado-lescents reported wh ether they ha d received an y form of t reatment fo r acurrent or past psychiatric disorder. The adults in Study 3 providedtreatment information as part of their diagnost ic interview.Althoughthe adults in Studies 1 and 2 provided similar information in responseto a quest ionnaire, w e only used treatment inform ation from Study 3data, so that the m easures of treatment received in the adolescent andadult samples would be comparable.For the teenage part icipants, inform ation about the n um ber of sui-cide attempts and the adolescent's h ighest level of suicidal ideation was

gathered as part of the diagnostic interviews. If any attempt had oc-cur red , th e diagnost ic interviewers noted whether th e at tempt oc-curred durin g a period of depression, as opposed to other mental prob-lems such as conduct disorder, mania, substance abuse, schizophrenia,and so forth.

Data AnalysisThe degree of comorbidity w as measured by the prevalence oddsratio (POR ), a measure of the association between a binary variable (o rrisk factor) and the occurrence of an event. A POR of 1.00 indicatesthat the likelihood of two disorders co-occurring is equal to chance,given the base rates of the two disorders. A n estimate of the asymp toticstandard error of the odds ratio can be used to approximate the confi-dence interval (CI) boundaries. If the value 1.00 falls wi th in the 95%CI, the odds ratio is not significant at p < 05.

ResultsPrevalence of Current and Lifetime Comorbidity

Adolescents. Asshown in the upper portion ofTable 1, adoles-cents who were depressed at the time of the diagnostic inter-view were more likely than expected by chance to havean addi-tional current mental disorder, except bipolar disorder. The lat-ter diagnosis had an extremely low prevalence rate. When theyoung women and men were examined separately, the patternsof current comorbidity with depression were comparable inregard to the presence of any psychiatric disorder and specifi-cally in regard to current anxiety or substance use disorders.Gender differences were noted for the comorbidity of currentdepression with disruptive behavior and eating disorders.Currently depressed young men were significantly more likelythan the nondepressed men to havea current diagnosis of con-duct or oppositional disorder (POR = 18.24, 95% CI = [5.20,63.98 ]). A similar degreeof comorbidity was not present for thecurrently depressed young women (POR = 0.99, CI = [0.98,1.00]). Conversely, currently depressed young women had sig-nificantly greater odds of having a comorbid eating disorder ascompared with the never depressed young women (POR =51.00, CI = [4.51, 576.29]). Eating disorders were extremelyrare in the young men, regardless of whether or not they weredepressed.

A s shown in Table 1, similar patterns were noted in the adoles-cent sample with regard to the rates of lifetime comorbidity ofdepression with other disorders for the total sample. In compar-ing lifetime comorbidity rates separately for the young womenand young men, one significant difference was noted. As in thecase of current comorbidity, l i fet ime depression was signifi-cantly comorbid with eating disorders only for the youngwomen (POR = 12.53, CI= [2.69, 58.40]). However,a lifetimehistory of depression was comorbid with disruptive behaviordisorders for both young men and young women.

Adults. The rates of current and l ifetime comorbidity of de-pression with other psychiatric disorders in the adult sample areshown in Table 2. With regard to current comorbidity withdepression, only substance use disorders were significantly co-morbid. As indicated by the POR, currently depressed personswere over three times more likely than expected by chance toalso have a current substance use disorder.


4/9

COMORBIDITY OF DEPRESSION 217Table 1Frequency o f the Prevalence Odds Ratio for Current and Lifetime Comorbidity o f OtherMental Disorders With Depression in the Adolescent Sample

Depressed Not depressedDisorder n % n % FOR CI

Current comorbidity

BipolarAnxietyDisruptive behaviorSubstance useEat ingAny disorder

( =0947221

= 5 0 ) 0.018.08.014.04.042.0

(n = 15452733111 7

;,660)0.32.71.62.00.17.0

1.007.885.268.0369.129.55

0.99, 1.003.61, 17.181.77, 15.653.36, 19.166 . 1 6 , 775 . 475.28, 17.27Lifetime comorbidity

BipolarAnxietyDisruptive behaviorSubstance useEatingAny disorder

( =37342699149

347) 0.921.012.119.92.642.9

( =87783734290

1,363)0.65.66. 15.40.321.3

1.484.452.124.399.052.78

0.39, 5.603.15,6.291 .44 ,3 .143.08, 6.252.77, 29.552 . 1 7 ,3 . 57

Note. FOR = prevalence odds ratio; CI = 95% confidence interval.

The likelihood that an adult with a lifetime history of depres- Temporal Order ofComorbid Disorderssion had an additional psychiatric disorder at some point in hisor her life w as significantly greater than expected by chance. As Adolescents. Given that depression w as significantly comor-with the adolescents, lifetime depression was significantly co- bid w ith other psychiatric disorders, we examined which of themorbid with substance use disorders. The two lifetime comor- two disorders was most likely to occur first. For a small propor-bidity findings rem ained significant wh en the w omen and men tion of the comorbid adolescent depressives (6.7%), the tw o dis-were exam ined separately. orders began dur ing the same time period, and therefore w e

Table 2Frequency o f and Prevalence Odds Ratio for Current and Lifetime Comorbidity o f OtherMental Disorders With Depression in the Adult SampleDepressed Not depressed

Disorder n % n % FOR CICurrent comorbidity

BipolarSchizophreniaAnxietyAntisocial personalitySubstance useAny disorder

(n =3020515

196) 1.50.01.00.02.67.7

( n = l16667213131

,864)0.90.33.60.10.77.0

1.800.900.280.903.731.10

0.52, 6.220.89, 0.920.07, 1.140.89, 0.921.31, 10.570.63, 1.91

Lifetime comorbidityBipolarSchizophreniaAnxietyAntisocial personalitySubstance useAny disorder

( =22293193221

869) 2.50.210.70.110.725.4

( =179106266202

1,191)1.40.88.90.15.517.0

1.790.301.231.372.041.67

0.95, 3.400.07, 1.410.91, 1.640.09,21.951 .47,2 .841.35,2.07Note. FOR = prevalence odds ratio; CI = 95% confidence interval .


5/9

21 8 P. R O H D E , P. L E W I N S O H N , AND J. S EELEYwere unable to determine a clear temporal order of onset. Thetempo ral order for the rem aining comorbid depressed adoles-cents is shown in the upper portion of Table 3.Depression in the comorbid teenagers was significantly morelikely to follow than to precede all but one of the otherpsychiat-ric disorders. The one exception was eating disorders, whichhad an extremely low prevalence rate. The p redom inant tem-poral pattern in w hich depression followed the other disorderw as especially striking w ith the anxiety disorders. In 85.1% ofthese comorbid cases, the depression began after the onset ofth e anxiety disorder.Adults. The temporal order of comorbid disorders in theadult sample appears in the lower portion of Table 3. When allother men tal disorders were combined into one category, co-morbid depression was more likely to follow than to precedethe other disorder. No significant temporal pattern emergedbetween depression and substance use disorders.Impact ofComorbidity on Depression

Differences between th e pu re d epressed an d comorbid de-pressed groups for the onset age and duration of the first de-pressive episode and the number of depressive episodes wereexamined and are shown in Table 4. In addition, th e currentpure depressed and comorbid depressed subjects were com-pared on severity of depression as measured by the CES-D.From th e assumption that th e presence of another psychiatricdisorder indicates more serious psychopathology, we predictedthat the depressed subjects wh o had another mental disorderwould have an earlier depression-onset age, a longer du rationfor the first depressive episode, a greater n um ber of depressiveepisodes, and a mo re severe curr ent depression, in addition tohaving other psychiatric disorders. Results for the adolescentand adult samples appear in Table 4.

Adolescents. As shown in the upper portion of Table 4, thecomorbid teenagers did not differ significantly on onset age ordur ation of depressive episode. The c urren t pure depressed ( n =29) and comorbid (n = 21 ) adolescents did not significantly

differ on mean CES-D score at the t ime of the interview (32.1and 33.9, respectively), F(\,48) = 1.30, ns . The comorbid adoles-cents, however, were significantly more likely than the puredepressed teenagers to have had mo re than o ne depressive epi-sode thus far in their life.Adults. The lower portion of Table 4 contains inform ationabout the onset age and duration of first depression and thenumber of depressive episodes in the pure depressed and co-mo rbid adults. Lik e the adolescents the adults did not differ onduratio n of depressive episode. For severity level of curre nt de-pression, the current pure depressed (n = 181) an d comorbid( w t = 15 ) adults did not significantly differ on mean CES-Dscores (21.3 and 26.3, respectively), F(l, 193) = 1.49, ns . In con-trast to th e findings for adolescents, the comorbid adults had asignificantly earlier age for the first depressive episod e but didnot have significantly more depressive episodes.Treatment Seeking an d Suicidal Behavior

Adolescents. Table 5 presents inform ation about treatmentseeking and suicidal behavior in the four diagnostic groups.The groups differed dramatically in w hether they ha d receivedtreatment for a mental disorder. Tw o post ho c contrasts weresubsequently conducted. Com pared with the n ever mentally illgroup, the three adolescent group s w ith mental disorders had asignificantly high er rate of treatment seeking, x 2(l, N= 1710) =276.50, p < .001. Second, the three diagnosed groups signifi-cantly differed among themselves in treatment seeking, x2(2 ,N = 637) = 18.15, p < .001; the comorbid group w as most likelyand the pure depressed group was the least likely to have re-ceived treatment.As can be seen in Table 5, the four groups differed in theproportion of adolescents who had attempted suicide. Thenever mentally il l group ha d significantly lower rates than th eother groups, X 2( l, N = 1710) = 99.77, p < .001. The threegroups w ith a diagnosis differed amo ng themselves in the per-centage with a history of suicide attempt, x2(2 , N = 637) =25.22, p < .001. Adolescents with disorders other than depres-

Table 3Temporal Order of Depression and Other Mental Disorders in the Adolescent and Adult Samples

Disorder

Depressionprecededother disorder Other disorderpreceded depression

Substance us eAny disorder 3668

AdolescentsAnxietyDisruptive behaviorSubstance useEatingAny disorder

101 122329

14.928.235.550.020.9

5728403110

85.171.864.550.079.1

5.62**2.57*2.59*1.006.78**Adults50.737.2

35115 49.362.8 0.053.38***p


6/9

COMORBIDITY OF DEPRESSI O N 21 9Table 4Comparison of Pure Depressed Versus Comorbid Adolescents an d Adultson Characteristics of Depressive Episode

Pure depressed ComorbidCharacteristic

Ag e of first depression onsetDurat ion of first depressiveepisode (in weeks)No. depressive episodes

M

(n =14.018.411.15

SDAdolescents

198) 2.8915.090.40

M

( =13.6910.191.32

SD

149) 3.0620.320.56

Test

F( 1 , 3 4 5 ) = 1.02U= 11,375.5F(l, 345) = 9.42*

AdultsAge of first depression onsetDurat ion of first depressiveepisode (in weeks)No. depressive episodes

(n38.451 10.291.52

= 648)15.86182.680.76

( n34.10128.011.46

= 221)15.45198.960.64

F(l,867) = 12.61**V = 79,988.0F( 1 , 8 6 7 ) = 1.08

*p w h o received treatment (n = 221)39.0 ( = 648)35.4 (n = 202)6.2 (n = 989)2. 7 X 2 ( 3 , 7 V = 1008) = 200.14*

Note. Means with different subscript letters were significantly different from each other in a Scheffe post ho c test.* />< ; . 001 .


7/9

220 P. R O H D E , P. LEWI NSO HN, AND J. SEELEYthe adolescents who experienced an episode of depression atthe tim e of the diagnostic interview were experiencing one ormore of the other mental disorders examined. With the omis-sion of eating disorders, w hich w ere relatively rare, the PORs fo rcurrent comorbidity with specific disorders ranged from 5.26for disruptiv e behavior disorders to 8.03 for substance use dis-orders.The results for the adolescents can be contrasted with thefindings of a study by Kashani et al. (1987), in w hich a muchsmaller (N = 150) sample of community-residing adolescentswere interviewed. In that study, 12 teenagers (8% of the sample)m et DSM-III crite ria for depressive disorders, and all of theseadolescents had an additional diagnosis (i.e., the current comor-bidity rate was 100%). As w e also found in our study, the de-pressed adolescents h ad an elevated rate of anxiety , disrup tivebehavior, and substance use disorders. Thus, the results fromth e tw o studies corroborate each other in the k inds of disordersthat are comorbid with depress ion but differ in the rate ofcurrent comorbidity (42% versus 100% ). Several possible expla-nat ions fo r th is difference may be suggested. First, th e relativelysmall sample size of the K ashani et al. study may have resultedin an unrepresentative sample. Second, th e very high rate ofcurre nt como rbidity reported by Ka shani et al. may have beendu e to the severity level of their depressed adolescents. In addi-t ion to meeting DSM-III criteria, all of the 12 depressed teen-agers were rated by the interview er and two child psych iatristsas show ing impaired func tioning and as being in need of treat-ment . Consistent w ith these potential ex planations for the dif-ferences in results from our study and from the K ashani et al.study is the fact that the y also found a greater overall prevalenceof all disorders. Although 2 6% o f their subjects with no affectivedisorder had another disorder, only 7% of the nondepressedadolescents in our sample had a diagnosed disorder. It is impor-tant to recognize that even though th e rate of current comor-bidity for the adolescent sam ple in our study was not as elevatedas that reported by Kash ani et al., the level still is quite high.Although a statistically significant degree of comorbidity w asfound for the ad ults, the levels of current and lifetime comor-bidity were low. The difference between th e adults and the ado-lescents may be related to the fact that the adults were diag-nosed according to RDC criteria, whereas the adolescents werediagnosed according to DSM-III-R criteria. The current andlifetime occurrence of depression in the adults w as significantlycomorbid only with substance use disorders. A s expected, therew as a somewhat higher lifetime occurrence of anxiety disordersin the depressed adults but this elevation w as not significant.To put our findings in perspective, it may be useful at thispoint to compare th e lifetime rates of mental disorders in theadolescents an d adults in our samples w ith those from th e E GAstudies, w hich were based on a large sample of persons 18 yearsof age or older (Regier et al., 1988). These data appear in Ta-ble 6.As can be seen, our adult sample had a m uch higher lifetimeprevalence of depression, which of course is to be expectedbecause many of the adults were chosen to be interviewed onthe basis of an elevated CES-D score. However, the lifetimeprevalence of major depression in the adolescent sample w asalso higher than that reported for the EC A data.Several possible reasons for this discrepancy can be offered.

Table 6Lifetime Prevalence of Disorders in the EpidemiologicCatchment Area (ECA) Data Set and in the Adultan d Adolescent Samples From This StudyDisorder ECA' Adults Adolescents

Major depressionDysthymiaSchizophreniaObsessive-compulsivePhobiaPanicAntisocial personalitySubstance use

.06.03.01.02.1 2.02.12.16

.38.09.01".01.04.01.001.08

.1 8.03.001.005.04.01

.08" Standardized lifetime prevalence rates for persons 18 years of age andolder in the ECA data set (taken from Regier et al, 1988). b Categorycombines lifetime prevalenceof schizophrenia an d schizoaffective dis-orders.

As was suggested by Parker (1987), the E CA lifetime prevalencerates for depression are discordant with prev ious find ings (e.g.,Murphy et al, 1984; Weissman & Myers, 1978) and are also toolow in comparison with the 6-month prevalence figures. Thefact that ou r lifetime rates fo r depression for the adolescents ar ehigher than those of the ECA for the adults may also reflectdifferences in the interview procedures betw een th e NationalInstitute of Mental H ealth Diagnostic Interview Schedule andth e Schedule fo r Affective Disorders an d Schizophrenia.Another difference is that the total prevalence of anxiety dis-orders in both our adult and adolescent samples is much lowerthan in the E CA studies. This difference appears to be dueprimari ly to the higher prevalence of phobias in the EC A stud-ies. The prevalence of substance use disorders in our adult sam-ple is also m uch low er than in the E CA samples. This may bedue to two factors. First, w e oversampled th e elderly. Thu s w ehad m any participa nts born early in this century, and it is likelythat these birth co horts have particularly low rates of substanceuse disorders. Second, substance dependent adults, regardlessof their age, m ay have been less likely to participate in ourstudies. These assumptions may also account for the low preva-lence of antisocial personality disorders in our adult sample.It is imp ortan t to note that w e could not study the comorbid-ity of depression with disorders that occurred w ith very lowfrequency in our samples, such as schizophrenia, serious sub-stance abuse problems, and antisocial personality disorder.Even though a large num ber of subjects w ere interviewed, thenum ber of participants w ith these disorders w as very small, andnegative findings need to be interpreted w ith caution. To exam-ine the comorbidity of depression with less frequent disorderswould have required oversampling fo r these disorders in thegeneral population.As expected, the frequency of suicide attempts and the de-gree of suicidal ideation w as elevated in the depressed teen-agers, an d both measures of suicidal behavior were especiallyhigh in the comorbid depressed adolescents, one four th o fwhom had m ade a suicide attempt. C ompared w ith purely de-pressed teenagers, teenagers w ith a disorder other than depres-sion had a lower rate of suicide attempts and a much lowerdegree of suicidal ideation. These findings suggest that al-


8/9

CO MO RBI DI TY O F DEPRESSION 221though depression is an impo rtant factor in adolescent suicide,those adolescents who have another mental disorder in con-junc tion w ith depression are at greatest risk.

Although the comorbidity of depression w ith another mentaldisorder did not significantly impact the duration and severityof the depression in either adolescents or adults, it apparentlyacted as a stimulus for the adolescents to receive treatment: 45 %of the comorbid adolescents had received treatm ent, comparedwith 30% of those with other disorders and 24% of the puredepressed. The results suggest that the presence of the otherdisorder substantially augmented th e likelihood that a de-pressed adolescent received treatment. The pattern of treat-ment seeking among the adult groups w as noticeably different.Unlike the teenagers, adults were most likely to have soughttreatment w hen depressed; the presence of another men tal dis-order did not substantially increase treatment utilization.The findings with regard to temporal order are of theoreticalimportance. F or most comorbid adolescents the other mentaldisorder preceded the depression. Similarly, depression in theadults w as more likely to follow than to precede the other men -tal disorder in general, although this pattern did not apply tosubstanc e use disorders. T he fact that depression was morelikely to follow the occurrence of another mental disorder isconsistent w ith theoretical form ulations, such as that of Lewin-sohn, Hob erman, Teri, and Hautzinger (1985), which concep-tualize the depressive episode as being evoked by the occur-rence of stressful events, that is, events that disrup t person-en-vironment interactions an d ongoing behavioral patterns. It isreasonable to assume that th e development of a men tal disorderis likely to be disruptive to interactions between persons andtheir environm ent and consequently to increase their likeli-hood of becoming depressed.In interpreting the results of any study, on e must ask whetherth e findings can be generalized to other populations or areunique to the particula r sample. It is probably fair to say that nosample is ever perfectly representative of the larger populationfrom w hich it was draw n, and ours likew ise is not. O ur interestin generating a large num ber of adults w ith a history of depres-sion may have resulted in biased samples. For the adolescents,however, we made a strong effort to have a representative andrandom sample of the population of high school students fromwhich they were chosen, and the adolescent results probably aregeneralizable to other community samples.Perhaps the most important finding to emerge from thisstudy is the high degree of com orbidity in the depressed adoles-cents. This finding clearly ha s important clinical and theoreti-ca l implications. Clinically, the possibility of comorbidity indepressed adolescents needs to be seriously considered and in-corporated into assessment procedures and may require a moreextensive treatment plan. Theoretically, a num ber of issues needto be addressed. First, why is the rate of comorbidity in de-pressed teenagers so high? Second, is the degree of como rbidityas elevated for other disorders? In other w ords, are all disordersin adolescence highly comorbid, or is this finding unique todepression? In conclusion, the significance of this finding pres-ents a challenge that w ill need to be replicated and addressed infuture research. T he fact that depressed adolescents are muchmore likely to have a comorbid mental disorder than persons

who become depressed later in life suggests that early-onsetdepression is a more serious form of the disorder.References

Alloy, L. B., Kelly, K. A., Minek a, S., & Clements, C. M . (1990). Comor-bidity ofanxiety and depressive disorders:A helplessness-hopeless-ness perspective. In J. D. Maser & C. R. Cloninger (Eds.),Comorbi-dity in anxiety and m ood disorders (pp. 499-544). Washington, DC :American Psychiatric Press.Am erican Psychiatric Association. (1980). Diagnostic and statisticalmanual of mental disorders (3rd ed.). Washington, DC : Author.American Psychiatric Association. (1987). Diagnostic and statisticalmanual of mental disorders (Rev. 3rd ed.). Washington, DC : Author.Andreasen, N. C., & W inokur, G. (1979). Secondary depression: F amil-ial, clinical an d research perspectives. American Journal of Psychia-try, 136, 62-66.Angst, J., & Dobler-Mikola, A. (1985). Th e Zurich studyA prospec-tive epidemiological study of depressive, neurotic and psychoso-matic syndrom es: IV Recu rrent and non recurrent brief depression.European Archives of Psychological and Neurological Science, 234,408-416.Angst, J., Vollrath, M., Merikangas, K . R ., & E rnst, C. (1990). Com or-bidity of anxiety and depression in the Zu rich Cohort Study of youngadults. In J. D. Maser & C. R. C loninger (Eds.), Comorbidity in anxi-ety and mood disorders (pp. 123-138). Washington, DC : Amer icanPsychiatric Press.Barlow, D. H., DiNardo, P. A. , Vermilyea,B. B., Vermilyea, J., & Blan-chard, E. B. (1986). Comorbidity and depression among the anxietydisorders: Issues in diagnosis an d classification. Journal of Nervousand Mental Disorders, J 74 , 63-72.Bowlby, J. (1960). Separation anxiety. International Journal of Psycho-analysis, 41 , 89-113.Boyd, J. H., Burk e, J. D., Gru enberg , E., Holzer, C. E., Rae, D. S.,George, L. K., Karno, M., Stoltzman, R., McEvoy, L., & Nestadt , G.(1984). Exclusion criteria of DSM-III: A study of co-occurrence ofhierarchy-free syndromes. Archives of General Psychiatry, 41 , 983-989.Breier, A., Charney, D. S., & Heninger, G. R. (1984). Majo r depressionin patients w ith agoraphobia an d panic disorder. Archives of GeneralPsychiatry, 41 ,1129-1135.Breier, A. , Charney, D. S., & H eninger, G. R. (1985). The diagnosticvalidity of anxie ty disorders an d their relationship to depressive ill-ness. American Journal of Psychiatry, 142, 787-797.Cadoret, R . J., Widm er, R. B., & Troughton, E. P. (1980). Somatic com -plaints: Harbinger of depression in primary care. Journal of A f f e c t i v eDisorders, 2,61-70.Dealy, R. S., Ishiki , D. M ., Avery, D. H. , Wilson, L. G, & D unner, D. L.(1981). Secondary depression in anxiety disorders. ComprehensivePsychiatry, 22 , 612-618.Endicott, J., & Spitzer, R. L. (1978). A diagnostic interview : The Sched-ule for Affective Disorders an d Schizophrenia. Archives of GeneralPsychiatry, 35 , 837-844.

Gersh, F. S., & Fow les, D. C. (1979). Neurotic depression: The conceptof anxious depression. In R. A . Depue (Ed.), Thepsychobiologyofthedepressive disorders: Implications for the e f f e c t s o f stress (pp. 81 -104).San Diego: Academic Press.Hirschfeld, R. M., Hasin, D., Keller, M . B., Endicott, J., & W under, J.(1990). Depression an d alcoholism: C omorbidity in a longitudinalstudy. In J. D. Maser & C. R . Cloninger (Eds.), Comorbidity in anxietyand mood disorders (pp. 293-304). Wa shington, DC: A merican Psy-chiatric Press.Kashani, J. H., Carlson, G. A., Beck, N. C., Hoeper, E. W , Corcoran,C. M., McAllister, J. A., Fallahi, C., Rosenberg, T. K., & R eid, J. C.


9/9

22 2 P. ROHDE, P. LEWINSOHN, AND J. SEELEY(1987) . Depression, depressive symptoms, and depressed moodamong a community sample of adolescents. American Journal ofPsychiatry, 144, 931-934.

Katon, W, K le inman , A. , & Rosen, G. (1982). Depression an d somati-zation: A review, Part I. American Journal of Medicine, 72,127-135.Keller, M. B. , Klerman, G. L., Lavori, P. W, Coryell, W , Endicott, J., &Taylor, J. (1984). Long-term outcome of episodes of major depres-

sion. Journal of th e American Medical Association, 252, 788-792.Keller, M . B., Lavori, P. W, Lewis, C. E., & Klerman, G. L. (1983).Predictors of relapse in major depressive disorder. Journal of th eAmerican Medical Association, 250, 3299-3304.Keller, M . B., & Shapiro, R . W (1982). "Double depression": Superim-position of acute depressive episodes on chronic depressive dis-orders. American Journal of Psychiatry, 139, 438-442.Klein, D . M., Taylor, E . B., Harding, K., & Dickstein, S. (1988). Doubledepression and episodic major depression: Demographic, clinical,familial , personality, and socioenvironmental characteristics andshort-term outcome. American Journal of Psychiatry, 145, 1226-

1231.Kovacs, M ., Paulauskas, S., Gatsonis, C., & Richards, C. (1988). De-pressive disorders in childhood: III. A longitudina l study of comor-bidi ty with an d risk fo r conduct disorders. Journal of Affective Dis-

orders, 15, 205-217.Kupfer, D. J., & Carpenter, L. L. (1990). Clinical evidence of comor-bidity: A critique of treated samples an d longitudinal studies. In J. D.Maser & C. R . Cloninger (Eds.), Comorbidity in anxiety an d mooddisorders (pp. 231-238). Washington, D C : American Psychiatric

Press.Leckman, J. E, Weissman, M . M., Merikangas, K. R ., Pauls, D. L., &PrusofF, B. A . (1983). Panic disorder an d major depression: In -creased risk of major depression, alcoholism, panic, and phobic dis-orders in families of depressed probands with panic disorder. A r-chives of General Psychiatry, 40 , 1055-1060.Lewinsohn, P. M., Hoberman, H., Teri, L., & Hautzinger, M . (1985).An integrative theory of depression. In S. Reiss & R . R . Bootzin(Eds.) , Theoretical issues in behavior therapy (pp. 331-359). San

Diego: Academic Press.Lew insohn, P. M., Hops, H., Roberts, R. E., & Seeley, J. R. (1988, No-vember) . Th e prevalenceof affective an d other disorders among olderadolescents. Paper presented at the meeting of the American PublicHealth Association, Boston.Lew insohn, P . M. , Rohde, P., Seeley, J. R ., & Hops, H. (1991). Comor-bidity of affective disorders: I. Major depression with dysthymia.

Journal of Abnormal Psychology, 100, 205-213.Maser, J. D, & Cloninger, C. R . (Eds.). (1990). Comorbidity in anxietyan d mood disorders. Washington, DC: American Psychiatric Press.Mezzich, J . E., Ahn, C. W, Febrega, H., & Pilkonis, P. A. (1990). Pat-terns of psychiatric Comorbidity in a large population presenting fo rcare. In J. D. Maser & C . R . Cloninger (Eds.), Comorbidity in anxiety

an d mood disorders (pp. 189-204). Washington, DC: American Psy-chiatric Press.Murphy, J. M., Sobol, A. M., Neff, R. K., Olivier, D. C., & Leighton,A. H. (1984). Stability of prevalence: Depression an d anxiety. Ar-chives of General Psychiatry, 41 , 990-997.Orvaschel, H., Puig-Antich, J., Chambers, W , & Johnson, R . (1982).Retrospective assessment of prepubertal major depression with th eKiddie-SADS-E. Journal of the American Academy of Child Psychia-try, 21 , 392-397.Parker, G. (1987). Are the lifetime prevalence estimates in the ECAstudy accurate? Psychological Bulletin, 17 , 275-282.

RadlofF, L. (1977). Th e CES-D Scale: A self-report depression scale forresearch in the general population. Applied Psychological Measure-ment, 1, 385-401.Regier, D. A. , Boyd, J. H., Burke, J. D, Rae, D. S., Myers, J. K., Kramer,M., Robins, L. N., George, L. K., Karno, M., & Locke, B. Z. (1988).One-month prevalence of mental disorders in the United States. A r-chives of General Psychiatry, 45 , 977-986.Regier, D. A. , Burke, J. D, & Burke, K. C. (1990). Comorbidity ofaffective an d anxiety disorders in the NIMH Epidemiologic Catch-ment Area program. In J. D. Maser & C. R . Cloninger (Eds.),Comor-bidityin anxiety and'mooddisorders (pp .113-122) . Washington,D C:American Psychiatric Press.Rohde , P., Lewinsohn, P. M., & Seeley, J. R. (1990). Are people changedby th e experienceof having an episode of depression? A further testof the scar hypothesis. Journal of Abnormal Psychology, 99 , 264-271.Seligman, M. E. P. (1975). Helplessness: On depression, development ,and death. San Francisco: Freeman.Spitzer, R. L., Endicott, J., & Robins, E . (1978). Research DiagnosticCriteria: Rationale and reliability. Archives of General Psychiatry, 35 ,773-782.Spitzer, R. S., Endicott, J., & Robins, E . (1985). Research DiagnosticCriteria (Rev. ed.). New York: Ne w York State Psychiatric Institute.Weissman, M. M. , Leaf, P. J., Bruce, M. L., & Florio, L. (1988). Theepidemiology of dysthymia in five communities: Rates, risks, co -morbidity, and treatment. American Journal of Psychiatry, 7 , 815-819.Weissman, M. M., & Myers, J. K. (1978). Affective disorders in a US.urban community.Archivesof General Psychiatry, 35 , 1304-1311.Weissman, M . M., Myers,J. K., & Harding,P. S. (1980). Prevalence andpsychiatric heterogeneity of alcoholism in a United States urbancommuni ty . Journal of Studies on Alcohol, 41 , 672-781.Winokur , G, Black, D. W, & Nasrallah, A. (1988). Depressions second-ar y to other psychiatric disorders and medical illnesses. AmericanJournal of Psychiatry, 145, 233-237.

Received April 27,1990Revision received November 20,1990Accepted November 21 ,1990

5- comorbidity of unipolar depression ii. comorbidity

Documents