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Open Access Research article

Definitions and factors associated with subthreshold depressive conditions: a systematic review

Mar Rivas Rodríguez12, Roberto Nuevo12, Somnath Chatterji3 and José Luis Ayuso-Mateos124*

Author affiliations

1 Instituto de Salud Carlos III, Centro de Investigación Biomédica en Red de Salud Mental, CIBERSAM, Madrid, Spain

2 Department of Psychiatry, Universidad Autónoma de Madrid, Hospital Universitario de la Princesa, Madrid, Spain

3 Department of Health Statistics and Informatics, World Health Organization, Avenue Appia 20, Geneva 27, CH 1211, Switzerland

4 Hospital Universitario de La Princesa, C./Diego de León 62, Madrid, 28006, Spain

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Citation and License

BMC Psychiatry 2012, 12:181  doi:10.1186/1471-244X-12-181

Published: 30 October 2012

Abstract

Background

Subthreshold depressive disorders (minor and subthrehold depression) have been defined in a wide range of forms, varying on the number of symptoms and duration required. Disability associated with these conditions has also been reported. Our aim was to review the different definitions and to determine factors associated with these conditions in order to clarify the nosological implications of these disorders.

Methods

A Medline search was conducted of the published literature between January 2001 and September 2011. Bibliographies of the retrieved papers were also analysed.

Results

There is a wide heterogeneity in the definition and diagnostic criteria of minor and subthreshold depression. Minor depression was defined according to DSM-IV criteria. Regarding subthreshold depression, also called subclinical depression or subsyndromal symptomatic depression, between 2 and 5 depressive symptoms were required for the diagnosis, and a minimum duration of 2 weeks. Significant impairment associated with subthreshold depressive conditions, as well as comorbidity with other mental disorders, has been described.

Conclusions

Depression as a disorder is better explained as a spectrum rather than as a collection of discrete categories. Minor and subthreshold depression are common conditions and patients falling below the diagnostic threshold experience significant difficulties in functioning and a negative impact on their quality of life. Current diagnostic systems need to reexamine the thresholds for depressive disorders and distinguish them from ordinary feelings of sadness.