chronic low back pain and depression

4
K. RANOA RAMA KRISHNAN. M.B. RANDAL D. FRANCE. M.D. JEFFREY L. HOUPT. M.D. ' Chronic low back pain and depression Dr. Krishnan and Dr. France are both assistant professors at Duke University Medical Center. Dr. Houpt is choirman ofthedepanment of psychiatry at Emory University, and at the time of this study he was prOfessor of psychiatry at Duke University Medical Center. Reprint requests to Dr. France, Department of Psychiatry, Duke University Medical Center, Box 3903, Durhom. NC 27710. ABSTRACT: In an attempt to clarify the relationship between chronic low back pain and depression, the authors studied the incidence of depression, alcoholism, and chronic back pain in first-degree relatives of chronic pain patients with and without depression. A higher incidence of recurrent unipolar depression was found in those relatives of patients with depression than without depression. These findings raise questions about the concept of chronic low back pain simply as a variant of depression and they suggest that the occurrence of major depression together with chronic back pain might relate to genetic vulnerability to depression. Chronic pain syndrome is often asso- ciated with depression.' but the exact nature of this association remains un- clear. Some 2 have considered chronic pain a variant of depression; others' have conceptualized it as masked depression. These hypotheses have been based on the assumption that pa- tients with chronic pain share many features with depressed patients. such as anhedonia, appetite and sleep dis- turbances. , ,2 response to tricyclic drugs,· neuroendocrine abnonnali- ties,> and increased familial incidence of alcoholism and depression. 2 .• However. as Williams and Spitzer' have pointed out, the evidence for chronic pain as a variant of depression is not compelling. Pilowsky and associates' examined the characteristics of depression in pain clinic patients and found that about 10% of them had a depressive syndrome. In a later study. Pilowsky and Bassett" noted a number of differ- ences between patients with chronic pain and those with depression in de- mographic characteristics, abnormal illness behavior patterns, and recall of childhood events. Maruta and asso- ciates lO also found similar differences between chronic pain patients and pa- tients with depression. In a recent review" we noted that at present insufficient evidence is avail- able for the efficacy of tricyclic anti- depressants in the treatment of pain. without depression. In a study'2 of the dexamethasone suppression test in chronic low back pain patients, we found a 40% incidence of abnormal suppression of cortisol in patients with major depression, but normal sup- pression in patients without it. These studies clearly raise questions about chronic pain being regarded simply as a variant of depression or as masked depression. In this paper we describe a prelimi- nary study undertaken to further clar- ify the relationship between chronic low back pain and depression by com- paring the frequency of depression, alcoholism, and chronic low back pain in first-degree relatives of APRIL 1985 VOL 26 NO 4 199

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Page 1: Chronic low back pain and depression

K. RANOA RAMA KRISHNAN. M.B.

RANDAL D. FRANCE. M.D.

JEFFREY L. HOUPT. M.D. '

Chronic low back painand depression

Dr. Krishnan and Dr. France are both assistant professors at Duke University MedicalCenter. Dr. Houpt is choirman ofthe depanment ofpsychiatry at Emory University, andatthe time ofthis study he was prOfessor ofpsychiatry at Duke University Medical Center.Reprint requests to Dr. France, Department ofPsychiatry, Duke University MedicalCenter, Box 3903, Durhom. NC 27710.

ABSTRACT: In an attempt to clarify the relationship between chroniclow back pain and depression, the authors studied the incidence ofdepression, alcoholism, and chronic back pain in first-degreerelatives of chronic pain patients with and without depression. Ahigher incidence of recurrent unipolar depression was found in thoserelatives of patients with depression than without depression. Thesefindings raise questions about the concept of chronic low back painsimply as a variant of depression and they suggest that theoccurrence of major depression together with chronic back painmight relate to genetic vulnerability to depression.

Chronic pain syndrome is often asso­ciated with depression.' but the exactnature of this association remains un­clear. Some2have considered chronicpain a variant of depression; others'have conceptualized it as maskeddepression. These hypotheses havebeen based on the assumption that pa­tients with chronic pain share manyfeatures with depressed patients. suchas anhedonia, appetite and sleep dis­turbances. ,,2 response to tricyclic

drugs,· neuroendocrine abnonnali­ties,> and increased familial incidenceof alcoholism and depression. 2.•However. as Williams and Spitzer'have pointed out, the evidence forchronic pain as a variant ofdepressionis not compelling.

Pilowsky and associates' examinedthe characteristics of depression inpain clinic patients and found thatabout 10% of them had a depressivesyndrome. In a later study. Pilowsky

and Bassett" noted a number ofdiffer­ences between patients with chronicpain and those with depression in de­mographic characteristics, abnormalillness behavior patterns, and recall ofchildhood events. Maruta and asso­ciates lO also found similar differencesbetween chronic pain patients and pa­tients with depression.

In a recent review" we noted that atpresent insufficient evidence is avail­able for the efficacy of tricyclic anti­depressants in the treatment of pain.without depression. In a study'2 of thedexamethasone suppression test inchronic low back pain patients, wefound a 40% incidence of abnormalsuppression ofcortisol in patients withmajor depression, but normal sup­pression in patients without it. Thesestudies clearly raise questions aboutchronic pain being regarded simply asa variant of depression or as maskeddepression.

In this paper we describe a prelimi­nary study undertaken to further clar­ify the relationship between chroniclow back pain and depression by com­paring the frequency of depression,alcoholism, and chronic low backpain in first-degree relatives of

APRIL 1985 • VOL 26 • NO 4 199

Page 2: Chronic low back pain and depression

~ 1-Demographlc and Clinical Characteristics ofChronic Pain Patients WIth and WIthout Major

II Depression

"alor Nomelordep.....lon depresalon

(N = 34) (N=16) Significance

Mean age ± SO (yr) 49.82±3.30 46.18±4.31 NS'

SexMale 18 9 NSFemale 16 7

Mean duration of pain 3.36± 1.70 4.93±2.20 NS'± SO (yr)

Mean number of siblings 4.52 4.56 NS'

Number currently married 33 15 NS

History of operations: Yes 20 10 NStNo 14 6

Organic pathology present:Yes 28 14 NSNo 6 2

'Student/tesltChi·square tesl

Pain and depression

chronic low back pain patients withand without major depression.

ProcedureThe 50 consecutive chronic low backpain patients involved in this studyhad been admitted to a pain manage­ment unit after initial screening at anoutpatient pain clinic. The structureand functioning of the clinic and unithave been described elsewhere. 13 Allpatients admitted to the unit were thor­oughly investigated for somatic pa­thology that might be contributing tothe pain. These investigations includ­ed orthopedic and neurosurgical eval­uations, electromyography (EMG),computed tomography, and myelog­raphy.

The inclusion criterion for the studywas the presence of daily low backpain for more than six months, with

300

that pain being the major complaintfor which help was soug~t. Based onthe above evaluations, none of the pa­tients had a somatic basis for the pain.Although 84% (42) of them had ab­normal EMG or physical findings,these findings often related to priorsurgery or injury and were not thoughtby neurosurgical and orthopedic con­sultants to be sufficient to account forthe chronic pain. Each patient was in­terviewed by one of the authors (RF orRK), and a lifetime diagnosis utilizingResearch Diagnostic Criteria (ROC)was formed as to whether or not thepatient had major depression, basedon medical records as well as on thatinterview. The proband was then in­terviewed by the other of the two au­thors, using the family history-ROCmethod." This interviewer for familyhistory was blind to the proband diag-

nosis made by the first interviewer.Family history data were obtainedonly for first-degree relatives.

Prior to initiation of the study, thetwo interviewers had obtained high in­terrater agreement (K = 1.0),using theROC, regarding the presence or ab­sence of major depression in six pa­tients. With regard to the family his­tory-ROC method, good interrateragreement (K=0.9) was achieved forthe major diagnosis, such as alcoholdependence, bipolar disorder. or re­current unipolar depression. Interrateragreement was poor (K=0.3) forchronic depression. This group wasnot included in the data analysis.

Morbidity risk was calculated usingan abridged Weinberg formula,

a

b - bo - bm

"2

in which a is the number of affectedindividuals. b is the total number of in­dividuals examined, bo the number ofindividuals who have not passed intothe risk period, and bm the number ofindividuals who are within the risk pe­riod. In addition to psychiatric disor­ders, a family history of back disor­ders was also obtained. No familymembers were interviewed. The agerange used for risk of alcoholism was20 to 40 years and for depression, ISto 60 years.

ResultsDemographic and clinical differencesbetween the two groups of chronicpain patients are shown in Table I.Thirty-four patients had major depres­sion, six of whom had it before the on­set of chronic back pain. The other 16patients did not have a history of majordepression or other psychiatric disor­ders. Sixteen of the patients with ma­jor depression satisfied criteria for en­dogenous depression, ROC type. Ac­cording to the probands, no family

PSYCHOSOMATICS

Page 3: Chronic low back pain and depression

Table 2-Morbidlty Risk (MR) for Affective Disordersand Alcoholism in Patients and Siblings of Chronic

Pain Patients With and Without Depression

Major depression No major depression

MR,% MR,% MR,% MR,%Family hi tory Parents Siblings Parents Siblingsdiagnosis-ROC (N=68) (N = 154) (N=32) (N=73)

Alcohol dependence 8.89 531 625 0

Remitting depression 0 2.56 667" 0

Recurrent unipolar 6.67 2.56 a 0depression

Bipolar disorder 1,67 128 0 0'The two parents who showed remitting depreSSion were both paren so the sameproband

history of psychopathology existed in27 (54%) of the families.

Table 2 shows the morbidity risk fordepression and alcoholism in parentsand siblings of chronic pain patientswith and without depression. Morbid­ity risk for recurrent unipolar depres­sion was higher in families of chronicpain patients with than withoutdepression. The risk for alcohol de­pendence in the parents of both groupswas not greatly dissimilar, but risk foralcohol dependence was higher in thesiblings of patients with depression.Four (12%) of the 34 probands withmajor depression had first-degree rel­atives with back problems suggestiveof disk pathology and two (13%) ofthe 16 probands without majordepres­sion had first-degree relatives withback problems. One proband with ahistory of major depression had a par­ent who had committed suicide. Onesibling of a patient with depressionhad schizoaffective disorder. None ofthe children of probands, both withand without depression, had any his­tory of psychiatric disorders or alco­holism. However. the significance ofthe results is limited because of thesmall sample size.

DiscussionThe findings indicate that chronicback pain patients with a lifetime his­tory of major depression differed fromsuch patients without major depres­sion in that a higher percentage offirst-degree relatives of probands withdepression had a history of affectivedisorders. Blumer and Heilbronn' re­ported in their study of chronic pain ahigher incidence of mental disorderssuch as depression in the families ofchronic pain patients. The fact thatthey did not separate out patients withand without major depression pre­cludes comparison of their findingswith our results. The higher incidencein their study might be a reflection of

APRIL 1985· VOL 26· NO 4

the incidence of major depression intheir population. A study· of 20chronic pain patients found that 73%of chronic pain patients with depres­sion and 40% of such patients withoutdepression had a family history ofdepressive spectrum disorder. How­ever, they did not provide sufficientdata to assess the morbidity risk ofdepression or alcoholism and thismakes it difficult to compare our re­sults with theirs.

The morbidity risk reported by usfor recurrent unipolar depression inthe families of chronic pain patientswith major depression is lower thanthat found in other studies. 15.11 Thisprobably is a consequence of themethod used. The family history­ROC method has limitations in termsof sensitivity. and this might have ledto underreporting of psychopatholo­gy. Increased sensitivity could havebeen obtained if family members hadbeen interviewed. The method doesproduce more false negatives thanfalse positives. I. Overreporting ofdepression in the relatives of de­pressed probands may occur. but thishas not been documented.

The morbidity risk for alcohol de­pendence in families of chronic painpatients is similar to that reported else­where" for families of probands withunipolar depression. probably indicat­ing that affective illness is transmittedin these families without regard towhether or not alcoholism is present.

Our findings indicate that the ideathat pain is a variant of depressionmight be an oversimplification of theissue. In some cases major depressioncould be a concomitant feature ofchronic back pain. This raises the pos­sibility that in some chronic pain pa­tients the occurrence of major depres­sion may relate to a genetic vulnerabil­ity to depression. The study must beregarded as preliminary in view of thelimited number of subjects. A familystudy ofchronic pain patients with andwithout depression may further clarifythe relationship between chronic painsyndromes and depression. 0

REFERENCES1 Sternbach RA: Pam Patients. Traits and Treat·

ment New York, Academic Press, 1974.2. Blumer D, Heilbronn M: Chronic pain as a var·

iant of depressive disease. The pain-pronedisorderJNervMentDis 170:381-406, 1979.

(continued)

301

Page 4: Chronic low back pain and depression

Pain and depression

3. Lopez-lbor J: Masked depression. Br J Psy­chiatry 120:245-258,1972.

4. Ward GN. Bloom VL, Friedel RO: The effecti·veness of tricyclic antidepressants in thetreatment of coexisting pain and depression.Pain 7:331-341, 1979.

5. Blumer D. Zorick F, Heilbronn M: Biologicalmarkers for depression in chronic pain. JNeN Ment Dis 170:425-428, 1982.

6. Schaffer CB, Donlan PT, Billie RM: Chronicpain and depression: A clinical and familyhistory survey. Am J Psychiatry 137: 118-120.1980

7. Williams JBW, Spitzer RL: Idiopathic pain dis­order. A critique of pain-prone disorder and aproposal for revision of the DSM-III categorypsychogenic pain disorders. J NeN Ment Dis170:415-419,1982.

8. Pilowsky I. Chapman CR, Bonica JJ: Pain,

CORRECTIONThe last three items were inadvertent­ly omitted from the Table in the re­cently published article, "Referral formedically unexplained somatic com­plaints: The role of histrionic traits,"by Phillip R. Slavney, Mark L. Teitel-

depression and illness behavior in a pain clin­ic population. Pain 4: 183-192, 1977.

9. Pilowsky I, Bassett DL: Pain and depression.Br JPsychiatry 14130-36,1982.

10 Maruta T, Swanson OW. Swenson WM Painas a psychiatric symptom Comparisonbetween low back pain and depression. Psy­chosomatics 17:123-127, 1976.

11 France RD, Houpt JL, Ellinwood EH: Thera­peutic effects of antidepressants in chronicpain. Gen Hosp Psychiatry 6:55·63, 1984

12. France RD, Krishnan KRR. Houpt JL. et al Dif­ferentiation of depression from chronic painwith the dexamethasone suppression testand DSM-1I1 AmJPsychiatry 141 :1577·1579,1984

13. Houpt JL, Keefe FJ. Snipes M The ClinicalSpecialty Unit: The use of the psychiatric in­patient unit to treat chronic pain syndromes.

baum, and Gary A. Chase (Psychoso­matics 26: 103-109, 1985). The para­graph referring to these lines conclud­ed: "The items least frequently ratedindicate that the referring physiciansdid not believe many patients to have

Gen Hosp Psychiatry 665-70. 198414. Andreasen NC. Endicott J, Spitzer RL: The

family history method using diagnostic crite­ria Reliability and validity. Arch Gen Psy­chiatry 341229-1235. 1977

15 Perris C Genetic transmission of depressivepsychoses Acta Psychiatr Scand203(suppl) 15-44. 1966

16 Smeraldi E. Negri F. Melica AM: A geneticstudy of affective disorder. Acta PsychiatrScand 56382-393. 1977

17. Gershon ES. Hamovlt J. Guroff JJ, et al: A fam­ily study of schizoaffective, bipolar I. bipolarII, unipolar and normal control probands.Arch Gen Psychiatry 391157-1167, 1982

18 Thompson WB. Orvaschel H, Prusoff BA, et al:Evaluation of family history method for ascer­taining psyChiatric disorder Arch Gen Psy­chiatry 3953-58. 1982

been malingerers (item 13), to havehad factitious illnesses (item 3), or tohave been motivated by secondarygain (items 14 and 15)." The correctTable appears below. We sincerely re­gret this error.

302

Table-Frequency With Which Checklist Items WereIndicated for 100 Patients by Referring Physicians

Item No.

2. The symptoms appear to be excessive for the physical findings.

1. The symptoms cannot be explained by the physical findings

5 The symptoms seem primarily emotional In nature rather than physical

7. The patient is self-dramatizing.

9. The patient is dependent.

8. The patient is attention-seeking.

12. The patient is demanding.

6. The patient cannot be reassured about his/her health.

11. The patient is suggestible about his/her symptoms.

14. The patient is using his/her symptoms to avoid responsibility.

10. The patient is vague about his/her symptoms.

4. The patient is indifferent to his/her disability.

15. The patient is using his/her symptoms for financial gain

13. The patient is lying about his/her symptoms.

3. The patient has injured himself/herself so as to produce symptoms

Frequency

69

65

48

43

41

33

32

30

21

19

18

11

8

6

5

PSYCHOSOMATICS