The three-dimensional questionnaire of depression (CTD): A new instrument for the measurement of sadness and depression

The elaboration and development of a new self-report instrument for the measurement of sadness and depression is presented in this paper: The Three-dimensional Questionnaire of Depression - CTD. This instrument is based on a multidimensional conceptualization of sadness as a basic and universal emotion, and depression as a pathological consequence of this emotion. In the elaboration of the CTD, the three-dimensional conception of emotions has been very successful in anxiety research. The knowledge derived from clinical research was examined in order to design an instrument that allows separate assessment of cognitive-subjective, physiological-somatic, and motor-expressive components of sadness/depression. Additionally, the CTD includes a suicide-prone-behavior scale, which is very useful in clinical contexts. Psychometric analyses of the CTD shows high reliability, both regarding test-retest reliability and internal consistency, high capacity to distinguish between normal and clinical populations, and a good convergent validity and solid factorial structure.