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Validation of the Time Course of Recovery by Voice Analysis

Recovery under Antidepressants

Investigations into antidepressant drug response are generally based on observer ratings or self-ratings. Therefore, the question arises as to the extent to which the respective results reflect the expectations of raters and patients. To tackle this question, we conducted a study of 43 hospitalized depressive patients to assess the time course of recovery at a dense time points throughout the first two weeks of treatment. Our sample included 17 mild cases (HAMD-17 baseline score < 22), 13 moderately depressed patients (HAMD-17 baseline score 22-27), and 13 severely depressed patients (HAMD-17 baseline score > 27). All patients were treated with antidepressants. The patients’ psychopathology was assessed on the basis of HAMD and AMDP rating scales, and speech recordings were carried out for each patient immediately before the psychiatric exploration. We performed six repeated assessments at a fixed time in the morning, each Monday, Wednesday and Friday, plus a final assessment upon release from hospital.

Onset of Improvement

The onset of improvement (20% sustained baseline score reduction) occurred in the great majority of patients (79.1%) within the first 12 days of study, independently of the severity of depression at baseline. Early improvement was highly predictive of later outcome, since 67.6% of the patients showing improvement within the first 12 days were responders (50% sustained baseline score reduction) by the end of the observation period. Inversely, 92% of the responders at the end of the observation period exhibited an onset of improvement within the first 12 days. Early improvement could not be attributed to a few HAMD items, because score reductions were observed for virtually all items at early stages of treatment.

Speaking Behavior and Voice Sound Characteristics

The analysis of the patients’ speaking behavior and voice sound characteristics yielded, in 62.8% of the cases, an essentially parallel development over time for the HAMD scores on the one hand, and acoustic variables on the other (see Figures). The time course of improvement thus appeared to have a strong biological component and was unlikely to be attributable to the expectations of doctors and patients.


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Stassen HH, Albers M, Püschel J, Scharfetter C, Tewesmeier M, Woggon B (1995) Speaking behavior and voice sound characteristics associated with negative schizophrenia. J Psychiat Res. 29, 277-296
Stassen HH (1995) Affekt und Sprache. Stimm- und Sprachanalysen bei Gesunden, depressiven und schizophrenen Patienten. Monographien aus dem Gesamtgebiete der Psychiatrie, Bd. 79. Berlin, Heidelberg: Springer
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Püschel J., Stassen HH, Bomben G, Scharfetter C and Hell D (1998) Speaking behavior and voice sound characteristics in acute schizophrenia. J. Psychiatric Research 32, 89-97
Stassen HH, Kuny S, Hell D (1998) The speech analysis approach to determining onset of improvement under antidepressants. Eur. Neuropsychopharmacology 8(4), 303-310
Lott PR, Guggenbühl S, Schneeberger A, Pulver AE, Stassen HH (2002) Linguistic analysis of the speech output of schizophrenic, bipolar, and depressive patients. Psychopathology 35(4): 220-227
Stassen HH, Angst J (2002) Wirkung und Wirkungseintritt in der Antidepressiva-Behandlung. In: Böker H and Hell D (eds) Therapie der affektiven Störungen. Stuttgart und New York: Schattauer 141-165
Stassen HH (2004) Veränderungen der Sprechmotorik. In: T.Jahn (ed) Bewegungsstörungen bei psychischen Erkrankungen. Springer Heidelberg: 107-125


voice analysis
Fig. 7: Time course of a patient's recovery from depression as reflected by HAMD-17 scores (green square points) assessed at two-day intervals over an observation period of two weeks, plus a final assessment at the time of discharge from hospital ("day63"). The corresponding change over time of the speech parameter "F0-amplitude" is also shown (red circle points) in order to demonstrate the close relationship between the two courses of development (all but one of the chosen patients responded to therapy).
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