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Home , Comorbidity, Mental disorder

Comorbidity of and Other

JMAJ 44(5): 225–229, 2001

Masaru MIMURA

Associate Professor, Department of , Showa University, School of

Abstract: This paper outlines the of depression and other diseases that are frequently seen in the primary care of depression. Since the operational diagnostic criteria of the DSM-III-R (Diagnostic and Statistical Manual of Mental Disorders, revised 3rd edition) and the current DSM-IV (4th edition) were intro- duced to Japan from the U.S., Japanese have become active in assign- ing a single patient parallel or overlapping diagnoses of mental disorders. In patients with depression, the comorbidity of disorder (, gen- eralized ), obsessive-compulsive disorder, dependence, alco- hol dependence, post-traumatic disorder, or is an issue. When depression is comorbid with another , both disorders are reported to be severer, more likely to be refractory, and more likely to be associ- ated with a poor prognosis. Although the concept of comorbidity in the field of mental disorders is useful in understanding patients’ symptoms and determining prognosis, it is also possible that the patient’s pathological structure is too greatly simplified. The concept of comorbidity should be employed within the limits of its clinical usefulness, while maintaining full recognition of this possible simplification. Key words: Comorbidity; Depression; Mental disorders; DSM-IV

Introduction period of time”. In Japanese, “comorbidity” is translated as “heison,” “heibyo,” or “kyoson,” Comorbidity is a term that has become but the original, untranslated English word is increasingly common during the past 10 years often used in practice. or so, particularly in the field of psychiatry as The assumption that a patient has comorbid practiced in Europe and North America. This mental disorders is often helpful in under- concept now represents a major theme in standing his or her pathological condition and clinical psychiatry. Comorbidity means the in formulating treatment policy and determin- state of being jointly (co-) morbid, and it is ing prognosis. General information on psychi- defined as “the presence of more than one atric comorbidity, including depression, has in a single person during a certain been the topic of several review articles that

This article is a revised English version of a paper originally published in the Journal of the Japan Medical Association (Vol. 124 No. 1, 2000, pages 55–58).

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have been published in Japanese psychiatric Comorbidity of Depression journals.1–3) This paper outlines the comor- bidity of depression and other diseases, focus- A large-scale national survey on the ing on those cases that frequently may be seen comorbidity of depression was carried out in the general clinical setting. in the U.S. principally by the University of Michigan.5) The results indicated that more Historical Development than half of all patients with a DSM-III-R diagnosis of major depressive disorder were Although the concept of the coexistence of associated with a comorbid anxiety disorder, two or more diseases is not at all new, conven- and that more than one-third of patients tional clinical psychiatry has tended to avoid showed the comorbidity of drug or alcohol it. Traditional psychiatric diagnostic criteria dependence. Thus it is safe to say that depres- have been presented as a stratified structure of sion is often present together with other men- independent disease classifications, and various tal disorders. According to Kessler et al.,5) symptoms have been subsumed under a single patients with pure depression, i.e., without psychiatric disease. For example, if a patient comorbidity, accounted for only one-fourth of had both depressive and compulsive symp- all patients with that diagnosis. However, as toms, depression and obsessive-compulsive approximately 20% of patients with depres- disorder were considered in the differential sion have comorbid post-traumatic stress dis- diagnosis, and the patient’s condition was gen- order (PTSD), diagnoses of these coexisting erally diagnosed as depression, a diagnosis disorders are based simply on the fact the that superseded obsessive-compulsive disor- patient has met the requirements for more der. Until recently there had been no ten- than one disease in the current operational dency to label a single patient with both of diagnostic criteria. This is because the previ- these diagnoses. ous system of diagnosis was likely to adopt However, since the operational diagnostic one diagnosis while deliberately or inadvert- criteria of the DSM-III-R (Diagnostic and ently excluding others; it does not mean that Statistical Manual of Mental Disorders, revised the comorbidity of mental disorders has 3rd edition) and the current DSM-IV (4th increased particularly in recent years. edition), which are based on multiaxial evalu- The presence of comorbidity brings several ation involving five axes,4) were introduced important issues to the surface. First, when from the U.S., the concept of psychiatric depression coexists with another mental disor- comorbidity has spread throughout clinical der, these disorders are reported to be severer practice in Japan, allowing Japanese psychia- than when either is present alone. The fre- trists to give a single patient two or more quencies of admissions and attempts diagnoses at the same time. Thus, a patient are higher, and the prognosis worse, in such as the one mentioned above would patients with comorbid depression.5) This be regarded as having both depression and trend is particularly prominent among young obsessive-compulsive disorder. The develop- patients with depression. A second issue is the ment of such parallel, overlapping diagnostic temporal relationship between depression and criteria in the U.S. seems to be grounded not other comorbid mental disorders. There are only on progress in the area of operational three ways of considering the order of onset6): diagnostic criteria but also on the finding that 1) When depression precedes the other disor- drug dependence is associated with various der, depression may serve as a causative factor mental disorders. for the subsequent disorder; 2) when the other disorder precedes depression, that disorder

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may serve as a causative factor for depression; therapy, to have markedly decreased social and 3) when depression and the other disor- function including occupational and marital der occur simultaneously, the symptoms of problems, and to have a high incidence these two diseases may be considered attribut- of attempted suicide, resulting in a poor able to a different cause(s). In general, in prognosis.6) patients with comorbid depression, the other mental disorder often precedes the initial epi- 2. Depression and obsessive-compulsive sode of depression (secondary depression), disorder and this is particularly so when the patient is Obsessions (such as irrational to male.5) certain ideas or repetitive thinking) or com- The comorbidity of depression and other pulsions (such as compulsive rituals or ascer- mental disorders is outlined below in relation tainment behavior) are known often to be to individual common disorders. concomitant with various mental disorders including , depression, and 1. Depression and anxiety disorder organic disease. As in cases of anxiety Comorbid anxiety disorder is the disorder disorder, secondary depression is also common most frequently found in patients with depres- in cases of comorbid obsessive-compulsive sion. Many researchers have reported that disorder and depression, with depression more than 50% of patients with panic disor- developing during the course of preceding der, characterized by sudden episodes of obsessive-compulsive symptoms. A survey of strong anxiety, or generalized anxiety disor- a large number of patients with obsessive- der, characterized by continuous anxiety, compulsive disorder showed that about one- experience at least one episode of depression third of them had comorbid depression at the in their lifetimes.5) Based on this high rate time of the survey and inferred that about of comorbidity, some researchers consider two-thirds of them would develop depression anxiety disorder and depression to have a sometime in their lives.8) common hereditary predisposition and differ- There are biological markers common to ences in clinical picture to result from differ- depression and obsessive-compulsive disorder, ences in phenotype influenced by environ- and serotonin-related , particularly selec- mental factors.7) Without going that far, it is tive serotonin reuptake inhibitors (SSRIs), are clear that many patients, at least clinically, effective for both depression and obsession. have symptoms of both depression and anxi- These findings suggest a biological relation- ety, and that the close relationship between ship between the two conditions. However, the two disorders has been pointed out. In the responses of depression and obsession to addition, the actions of and antide- are not necessarily the same pressants are considered to affect both condi- in patients with comorbidity. This is an issue tions. Further research on the comorbidity of that requires further investigation. these conditions, not only from the aspect of etiological studies and clinical evaluation, but 3. Depression and also from the viewpoint of psychopharmac- The association of depression and alcohol- ology, is awaited. ism has long been discussed. In a review As mentioned in the previous section, both of previous reports, Davidson et al.9) found depression and anxiety are severe in patients comorbidity between depression and alcohol- with comorbid depression and anxiety disor- ism in 16–88% of patients. According to the der. Moreover, these patients are more likely previously mentioned report by Kessler et al., to be resistant to tricyclic drug comorbid alcohol dependence or is

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present in nearly 30% of patients with depres- borderline (10–30%), histrionic (2–20%), anti- sion.5) When depression precedes alcoholism, social (0–10%), and obsessional (0–20%), alcoholism may be a symptom of depression, showing a great deal of diversity. Although the or the patient’s attempt to reduce depressive comorbidity of depression and personality dis- symptoms may result in alcoholism. It is order is of clinical importance, it is not an understandable that a patient may succumb to uncomplicated problem. It needs to be borne alcoholism in trying to relieve depression or in that the prognosis and treatment hostility. On the other hand, when alcoholism policy will vary according to the type of is present initially, the risk of developing comorbid personality disorder. depression is considered to be 2–3 times higher than that in the general population. 5. Depression and physical or neurologic Patients with alcoholism often fall into a diseases depressive state when they lose control of When depressive symptoms are present in drinking or are in a period of withdrawal. association with organic brain disease or gen- Therefore, caution is necessary when consider- eral physical diseases, as coded on axis III ing the nature of the comorbidity of depres- of DSM-IV, it is not particularly helpful to sion and alcoholism. It is also possible in some regard this as comorbidity of depression, as cases that common risk factors and heredity pointed out by Yoshimatsu.12) It would be are involved in the development of the two preferable to consider it a unified combination conditions. of the partial manifestations of underlying physical and organic disease or as a secondary 4. Depression and personality disorder response, if possible. For example, in It has been a firmly rooted belief that mood we often encounter patients with in disorder is related to premorbid personality whom a depressive state has preceded demen- disorder, and, specifically among psychiatrists tia. However, it seems to be of greater signifi- in this country, it is generally accepted that cance from the aspects of both early diagnosis unipolar depression and melancholic person- and integrated understanding of the patho- ality are related. However, recent etiological logical condition to regard the depressive state studies of a large number of patients have as the initial symptom of dementia rather than resulted in negative findings, indicating the consider it to be a case of comorbidity of need for caution with regard to this issue.10) depression and dementia. There is an interesting finding from the aspect of comorbidity between depression and per- Conclusion sonality disorder. According to DSM-IV,4) the original mental disorder is diagnosed on the Comorbid conditions that are likely to be first axis, and the accompanying personality seen frequently in the clinical setting for disorder, if any, is coded on the second axis. In primary care of depression have been out- this sense, the multiaxial diagnosis of DSM-IV lined. The concept of comorbidity expressed is based on the premise that comorbidity of through the names of multiple diseases that personality disorder and other mental disor- satisfy diagnostic criteria is rational from one ders exists. A recent review of patients with point of view, conforming as it does to certain depression indicated that some type of per- operational diagnostic criteria, and is helpful sonality disorder was present in 20–50% of in understanding a patient’s symptoms as well inpatients and 50–85% of outpatients with as in clarifying treatment and prognosis. How- depression.11) Among these patients, relatively ever, there is also the possibility that the frequent types of personality disorders were patient’s pathological structure is too greatly

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simplified into “a mosaic aggregate of a num- tion: results from the US National Comor- ber of diseases” (Yoshimatsu12)). The concept bidity Survey. Br J Psychiatry 1996; 168 of comorbidity should be employed within (suppl. 30): 17–30. the limits of its clinical usefulness, while 6) Ida, I.: Comorbidity of depression. Rinsho maintaining full recognition of this possible Seishin Igaku 1998; 27: 1503–1509. (in Japanese) simplification. 7) Kendler, K.S., Walters, E.E., Neale, M.C. et al.: The structure of the genetic and environ- REFERENCES mental risk factors for six major psychiatric disorders in women. Arch Gen Psychiatry 1) Higuchi, T. ed.: Special subject: Comorbidity 1995; 52: 374–383. of mental disorders I, II. Seishinka Chiryo- 8) Ohshima, A. and Higuchi, T.: Emotional gaku 1997; 12: 737–794 (I), 877–926 (II). disorder, panic disorder, and obsessive- (in Japanese) compulsive disorder: the meaning of comor- 2) Hirose, T. ed.: Concerning comorbidity of bidity from the biological viewpoint. mental disorders. Rinsho Seishin Igaku 1998; Seishinka Chiryogaku 1997; 12: 777–784. 27: 1495–1534. (in Japanese) (in Japanese) 3) The 93rd Meeting of the Japanese of 9) Davidson, K.M. and Ritson, E.B.: The rela- Psychiatry and : Symposium 5: tionship between alcohol dependence and “Comorbidity of Mental Disorders”. Seishin depression (invited review). Alcohol Alcohol Shinkeigaku Zasshi 1997; 99: 942–977. 1993; 28: 147–155. (in Japanese) 10) Sakamoto, K.: Depression and premorbid 4) American Psychiatric Association: Diagnostic personality. Rinsho Seishin Igaku 1998; 27: and Statistical Manual of Mental Disorders. 259–266. (in Japanese) 4th ed. (DSM-IV), APA, Washington, D.C., 11) Corruble, E., Ginestet, D. and Guelfi, J.D.: 1994. (Japanese version translated by Comorbidity of personality disorders and Takahashi, S., Ohno, Y. and Someya, T., unipolar major depression: a review. J Affect Igakushoin, Tokyo, 1996) Disord 1996; 37: 157–170. 5) Kessler, R.C., Nelson, C.B., McGonagle, K.A. 12) Yoshimatsu, K.: What is comorbidity? et al.: Comorbidity of DSM-III-R major Seishinka Chiryogaku 1997; 12: 739–749. depressive disorder in the general popula- (in Japanese)

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