Research report
Long-term depression versus episodic major depression: Results from the prospective Zurich study of a community sample

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Abstract

Background

Clinical studies have demonstrated a great clinical relevance of long-term depression (LTD). Our study aims to characterise LTD in comparison with episodic (non-chronic) major depressive episodes (MDE) on the basis of data from a community sample.

Method

The Zurich Cohort Study is a prospective study of young adults followed from age 20/21 to 40/41 with six interviews. The stratified sample consisted of two thirds high scorers and one third lower scorers on the Symptom Checklist-90 R (SCL-90-R). LTD was assessed from age 27/28 to 40/41 and defined as being symptomatic more days than not over 2 years plus the presence of work impairment. MDE and dysthymia were defined by DSM-III-R criteria.

Results

The cumulative incidence of LTD was 5.7%, and of episodic MDE 20.9%. In both groups we found a similar preponderance of women. LTD subjects reported disturbed memory, feelings of inferiority, hopelessness, fear of everyday tasks, fear of being alone and thoughts of dying significantly more often than subjects with episodic MDE. Subjects with LTD had an earlier age of onset. 82% of them were treated over lifetime for depression compared to 61% with MDE. LTD subjects were less often married, less often in fulltime employment, more often unemployed, and more often receiving social benefits.

LTD was comorbid with cardiac and respiratory syndromes, and LTD subjects were more frequently treated for insomnia and pain. They suffered significantly more from social phobia and benzodiazepine abuse; there was also a statistical trend to greater comorbidity with panic attacks, agoraphobia, obsessive–compulsive syndrome, binge eating and neurasthenia. Somatic and psychological well-being were also reduced.

Conclusions

LTD is common, clinically more serious than episodic MDE and highly comorbid.

Limitations

The sample is relatively small with an attrition rate of 38.5% over 20 years. The results cannot be generalised to persons over 40 years of age and may be dependent on the definition of LTD.

Introduction

There is no general agreement on the definition of long-standing, long-term, persistent or chronic depression (Marneros and Deister, 1990). For example, the DSM-IV includes a number of categories and specifiers for chronic depression, including chronic major depressive episode, dysthymic disorder, major depressive episode with antecedent dysthymia, major depressive episode in partial remission, and recurrent major depression with incomplete interepisode recovery (American Psychiatric Association, 2000). Definitions of chronic depression vary with respect to duration, including 1 year (Weissman and Klerman, 1977, Brown and Moran, 1994, Van Os et al., 2006), 2 years (Benazzi, 1999, Scott, 1988, Garvey et al., 1986, Guensberger and Fleischer, 1972), 3 years (Marneros and Deister, 1990), and course type since first onset of depression (Mondimore et al., 2006, Stewart et al., 2002). Definitions of chronic depression also differ with respect to severity (e.g., chronic major depression versus dysthymia) and patterning (e.g., double depression, major depression in partial recovery) (Klein, in press).

Compared to non-chronic depressions, chronic depressions are reported as being associated with an earlier onset (Mondimore et al., 2006, Gilmer et al., 2005), a greater number of episodes (Marneros and Deister, 1990, Benazzi, 1998), greater comorbidity with Axis I disorders (Mondimore et al., 2006, Gilmer et al., 2005, Holm-Denoma et al., 2006) and with Axis II conditions (Garyfallos et al., 1999, Markowitz et al., 1992, Pepper et al., 1995, Spalleta et al., 1996); higher levels of neuroticism (Hirschfeld, 1990, Klein et al., 1988b), introversion (Hirschfeld, 1990, Klein et al., 1988b), and depressotypic cognitions (Klein et al., 1988b, Riso et al., 2003); greater suicidality (Garvey et al., 1986, Mondimore et al., 2006, Gilmer et al., 2005, Holm-Denoma et al., 2006, Klein et al., 1988b, Klein et al., 2000) and functional impairment (Gilmer et al., 2005, Evans et al., 1995, Hays et al., 1995); more early adversity and maladaptive parenting (Brown and Moran, 1994, Brown et al., 1994, Lizardi et al., 1995); and higher rates of mood disorders in relatives (Klein et al., 1988a, Klein et al., 1995, Klein et al., 2004, Vocisano et al., 1996). Interestingly, unipolar and bipolar depression do not seem to differ in their rates of chronicity (Angst, 1989, American Psychiatric Association, 1987, Benazzi, 1999).

This study will characterise and compare long-term depression (LTD) and episodic (non-chronic) major depressive episodes (MDE) in terms of socio-demographic characteristics, symptom profiles, treatment, somatic and psychiatric comorbidity, coping skills and quality of life (well-being).

Section snippets

Sample

The Zurich study sample was selected from 4547 subjects (2201 males, 2346 females) aged 19 (m) and 20 (f), who were representative of the canton of Zurich in Switzerland. These subjects were screened in 1978 with the Symptom Checklist 90-R (SCL-90-R) (Derogatis and Cleary, 1977) in order to over-sample persons with high global severity indices (GSI) who would be more likely to develop psychiatric syndromes. A stratified random sample of 591 subjects (292 males, 299 females) was selected for

Subgroups of depression

Table 1 shows that 55 (23%) of all depressive subjects were classified as suffering from long-term major (n = 36) or minor (n = 19) depressive syndromes. They will be compared with 112 subjects with episodic MDE and with 75 milder depressives (MinD, RBD) and 183 subjects with no depression or depressive symptoms not meeting the criteria for milder depression during the 12 months prior to the six interviews. This group does include some undiagnosed cases, because the diagnoses do not refer to

Discussion

The purpose of this paper is to characterise and compare subjects with long-term depression (LTD) with those suffering from non-chronic major depressive episodes (MDE). On the basis of weighted cumulative incidence rates, 17.3% of all MDE subjects (diagnosed from age 27/28 to 40/41) suffered from LTD. The diagnostic composition of the LTD group, which was defined by a diagnosis of depression meeting the two-year duration criterion for dysthymia, is interesting. One fourth of LTD subjects

Conclusion

Compared to episodic MDE subjects, long-term depressives were found to be diagnostically more complex and more comorbid with some anxiety-related somatic and psychiatric syndromes. Their self-assessed symptom profile was partly more severe, and they reported multiple social and psychological consequences and reduced well-being.

Role of funding source

This work was supported by Grant 3200-050881.97/1 of the Swiss National Science Foundation. The foundation had no further role in study design; in the collection, analysis and interpretation of data; in the writing of the report; and in the decision to submit the paper for publication.

Conflict of interest

I certify that there are no actual or potential conflicts of interest including any financial, personal or other relationships with other people or organizations.

There is no relevant duality of interest with a company whose products or services are directly related to the subject matter of the manuscript, e.g. employment, consultancies, membership on an advisory panel, standing committee, board of directors, stock ownership, honoraria, paid expert testimony, patent applications/registrations,

Acknowledgement

This work was supported by Grant 3200-050881.97/1 of the Swiss National Science Foundation.

References (44)

  • AngstJ.

    Der Verlauf schizoaffektiver Psychosen

  • AngstJ. et al.

    The Zurich Study—a prospective epidemiological study of depressive, neurotic, and psychosomatic syndromes. IV. Recurrent and nonrecurrent brief depression

    Eur Arch Psychiatr Neurol Sci

    (1985)
  • BechP. et al.

    Quality of life in anxiety and social phobia

    Int Clin Psychopharmacol

    (1996)
  • BenazziF.

    Chronic depression: a case series of 203 outpatients treated at a private practice

    J Psychiatry Neurosci

    (1998)
  • BrownG.W. et al.

    Clinical and psychosocial origins of chronic depressive episodes. I. A community survey

    Br J Psychiatry

    (1994)
  • BrownG.W. et al.

    Clinical and psychosocial origins of chronic depressive episodes. II. A patient enquiry

    Br J Psychiatry

    (1994)
  • DerogatisR.L.
  • DerogatisL.R. et al.

    Factorial invariance across gender for the primary symptom dimensions of the SCL-90

    Br J Soc Clin Psychol

    (1977)
  • DunnG. et al.

    Two-phase epidemiological surveys in psychiatry

    Br J Psychiatry

    (1999)
  • EatonW.W. et al.

    Population-based study of first onset and chronicity in major depressive disorder

    Arch Gen Psychiatry

    (2008)
  • EvansS. et al.

    Social-vocational adjustment in unipolar mood disorders: results of the DSM-IV field trial

    J Affect Disord

    (1995)
  • GardnerA. et al.

    High somatic distress with high long-term stability in selected patients with chronic depression: a 3-year follow-up of ratings with Karolinska Scales of Personality (KSP)

    Nord J Psychiatry

    (2004)
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