Trial document





This trial has been registered retrospectively.
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  DRKS00016350

Trial Description

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Title

Olfactory training with patients suffering from depressive disorders

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Trial Acronym

OTDD

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URL of the Trial

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Brief Summary in Lay Language

We invited 102 patients suffering from depression to take part in a "smell training", smelling on four bottled odors daily for a time-period of four months to see if it helps reduce depressive symptoms and compared this effect to a depressive control Group that solved sudokus in the same time period.

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Brief Summary in Scientific Language

By means of a randomized controlled intervention study, we investigated whether olfactory training is a useful complementary strategy for depression treatment in a sample of 102 depressive out-patients.

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Organizational Data

  •   DRKS00016350
  •   2018/12/19
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  •   yes
  •   Approved
  •   EK48022015, Ethikkommission der Medizinischen Fakultät der Technischen Universität Dresden
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Secondary IDs

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Health Condition or Problem studied

  •   F32 -  Depressive episode
  •   F33 -  Recurrent depressive disorder
  •   F43.2 -  Adjustment disorders
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Interventions/Observational Groups

  •   Experimental group: Depressive Patients diagnosed with F32, F33 and F43.2 completed an olfactory Training over a time-period of 16 weeks. This daily short-time exposure comprised smelling on the four bottled odors rose, lime, eucalyptus and glove and rating intensity of the odors, mood and energy level in a "smell diary" once a week.
  •   Control group: Depressive Patients diagnosed with F32, F33 and F43.2 completed a "cognitive Training" over a time-period of 16 weeks. This comprised solving sudokus twice a day for five minutes and rating perceived difficulty of the task, as well as mood and energy level in a "Sudoku diary" once a week.
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Characteristics

  •   Interventional
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  •   Randomized controlled trial
  •   Open (masking not used)
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  •   Placebo
  •   Treatment
  •   Parallel
  •   N/A
  •   N/A
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Primary Outcome

We aimed to investigate in a sample of clinically depressed patients whether Olfactory Training (OT) has a positive effect on depressive symptoms, compared to a placebo training, which we expected not to show any beneficial effect. In line with the previous research in this field, we furthermore hypothesized that OT improves olfactory function and, as a “side effect”, cognitive function. On average, the post-test appointment was arranged 16 weeks after pre-test. The participants had to fullfill the Training on a regular Basis at least for 12 weeks to be included in the statistical data analysis.
Depressive symptoms were assessed using the Beck Depression Inventory (BDI-II; Beck et al., 1996; Hautzinger, Keller, & Kühner, 2006). Additionally, the 36-item Short Form Health Survey (SF-36) (Bullinger et al., 1995) was applied in the pre-test to measure health-related quality of life.
Olfactory function in terms of odor threshold and identification ability was measured with a validated and reliable forced choice paradigm using the Sniffin’ Sticks testing kit (Burghart GmbH, for a detailed description see (Hummel, Sekinger, Wolf, Pauli, & Kobal, 1997)). In addition to the assessment of objective olfactory function, we also asked our participants about their individual importance of olfaction with a questionnaire (Croy, Buschhüter, Seo, Negoias, & Hummel, 2010).
In order to control for a potential cognitive impact on olfactory function and affective disorders, two cognitive tests were performed with the participants: The revised d2 attention and concentration test (Brickenkamp & Zillmer, 1998), and the Regensburger verbal fluency test (RWT; Aschenbrenner, Tucha, & Lange, 2000).
In order to control for potential confounders accompanying diseases, we included a medical history questionnaire.
The recruitment ran continuosly between November 2015 and September 2017, so that the post-test data of the last participant was collected in September 2017.

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Secondary Outcome

In the same sample of depressive out-patients, we examined the influence of severity, course and duration of depression on olfactory function. We expected severity, course and duration of depression affecting olfactory function in terms of a reduction in olfactory function (odor identification and odor threshold). We used the same methods as described above to examine this research question. Furthermore, we divided the sample into three sub-groups, taking the BDI score, the diagnoses (F32 vs. F33) and duration of depression into account.

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Countries of Recruitment

  •   Germany
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Locations of Recruitment

  • University Medical Center 
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Recruitment

  •   Actual
  •   2015/11/05
  •   121
  •   Monocenter trial
  •   National
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Inclusion Criteria

  •   Both, male and female
  •   18   Years
  •   99   Years
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Additional Inclusion Criteria

Symptoms of an at least mild depression (BDI-score >13 and <20) served as inclusion criterion. Sufficient German skills and an age of >17 yrs were also mandatory.

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Exclusion Criteria

Exclusion criteria were diagnosed anosmia, chronic nasal diseases, neurodegenerative diseases, and metabolic diseases, as well as being currently affected with acute respiratory diseases like colds and influenza, although frequent respiratory diseases in their medical history were not an exclusion criterion. Furthermore, current psychological treatment, antidepressant medication or the admission into psychotherapeutic treatment facilities during the course of training was not an exclusion criterion due to ethical reasons, but was taken into account for in the statistical data Analysis.

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Addresses

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    • Klinik für Psychotherapie und Psychosomatik Universitätsklinikum Carl Gustav Carus
    • Ms.  Jun.-Prof.  Ilona  Croy 
    • Fetscherstr. 74
    • 01307  Dresden
    • Germany
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    • Klinik für Psychotherapie und PsychosomatikUniversitätsklinikum Carl Gustav Carus Dresden
    • Ms.  Dipl.-Psych.  Luise  Pabel 
    • Fetscherstr. 74
    • 01307  Dresden
    • Germany
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    • Klinik für Psychotherapie und PsychosomatikUniversitätsklinikum Carl Gustav Carus
    • Ms.  Dipl.-Psych.  Luise  Pabel 
    • Fetscherstr. 74
    • 01307  Dresden
    • Germany
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Sources of Monetary or Material Support

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Status

  •   Recruiting complete, follow-up complete
  •   2017/09/02
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Trial Publications, Results and other Documents

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* This entry means the parameter is not applicable or has not been set.