Aktuelle Neurologie 2007; 34 - P484
DOI: 10.1055/s-2007-987755

Motor phenotype assessment in patients with depressive disorders using isometric tongue force analysis – a readout for clinical studies?

N Bechtel 1, C Haberkamp 1, H Beckmann 1, B Baune 1, P Zwanzger 1, V Arolt 1, R Reilmann 1
  • 1Münster; Townsville, AUS

Background: Motor symptoms of depression are increasingly appreciated in the setting of research and clinical studies. Psychomotor slowing, for instance, has been identified as criterion for the severity of depression and is currently being assessed in standardized depression rating scales (e.g., Hamilton Rating Scale for Depression, DSM-IV). However, clinical ratings may be biased by subjective error and categorical scales are lacking high sensitivity. Therefore objective and quantitative measures of motor dysfunction would be desirable as possible outcome measures in clinical studies. In Huntington's Disease and ALS isometric tongue force variability (TFV) assessed by measuring tongue protrusion forces (=glossomotography) was shown to be a reliable measure of motor dysfunction and progression of disease (Reilmann et al. 2003, Wansing et al. 2006).

Objective: To investigate whether TFV assessed in an isometric tongue protrusion task is pathologically increased in patients with depression.

Subjects and methods: Patients with depression (n=10) and healthy controls (n=6) were instructed to protrude their tongue and push on a force transducer (Mini-30, ATI, USA) 2cm in front of their mouth. They were told to match force levels of 0.25 N, 0.5 N, and 1.0 N, presented on a monitor, for 30s (5 trials at each level). Data was recorded and analyzed using a flexible laboratory computer system (SC/ZOOM, University of Umeå, Sweden). TFV (i.e. coefficient of variation of tongue forces) was calculated during a 20s period. The non-parametric Mann-Whitney-Test was used to compare patients with controls. Significance was assumed at p<0.05 level.

Results: TFV was significantly increased in patients with depression in the 0.5 N condition and exhibited a tendency for increased values in the 0.25N and 1.0N conditions that failed to reach statistical significance.

Conclusion: The results suggest that isometric TFV may be an objective measure to assess the severity of motor dysfunction in depression. Significant differences between patients and controls were only found in one force level. This may be explained by the small number of patients and controls in this preliminary analysis. A possible use of TFV as a surrogate marker in treatment trials in depression should be assessed in larger cross-sectional and follow-up studies.