Long-term depression versus episodic major depression: results from the prospective Zurich study of a community sample.
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.


METHODS
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.


CONCLUSIONS
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.
Angst
Jules
J
Zurich University Psychiatric Hospital, Lenggstrasse 31, P.O. Box 1931, CH-8032 Zurich, Switzerland. jangst@bli.unizh.ch
Gamma
Alex
A
Rössler
Wulf
W
Ajdacic
Vladeta
V
Klein
Daniel N
DN
D000293:Adolescent; D000328:Adult; D017668:Age of Onset; D002908:Chronic Disease; D003072:Cognition Disorders / Q000175:diagnosis / Q000188:drug therapy / Q000453:epidemiology / Q000523:psychology; D003430:Cross-Sectional Studies; D003469:Culture; D003866:Depressive Disorder / Q000175:diagnosis* / Q000188:drug therapy / Q000453:epidemiology / Q000523:psychology; D003865:Major Depressive Disorder / Q000175:diagnosis* / Q000188:drug therapy / Q000453:epidemiology / Q000523:psychology; D019263:Dysthymic Disorder / Q000175:diagnosis / Q000188:drug therapy / Q000453:epidemiology / Q000523:psychology; D006306:Health Surveys; D006801:Humans; D015994:Incidence; D007406:Interview, Psychological; D008137:Longitudinal Studies; D009042:Motivation; D011446:Prospective Studies; D011619:Psychotropic Drugs / Q000627:therapeutic use; D012008:Recurrence; D012649:Self Concept; D012959:Socioeconomic Factors; D013557:Switzerland; D055815:Young Adult
D011619:Psychotropic Drugs