Scales of depression, ill-being and the quality of life--is there any difference? An assay in taxonomy.

The application of a model based on the three time dimensions of past, present and future can be used to generate an alternative taxonomy for the classification of depression, ill-being and quality of life. In relation to time, depression can be defined as the passage from a healthy past to a painful present, ill-being as the painful present of the individual and the quality of life (QOL) as the degree to which the subject's present life is commensurate with his aspirations. Such an approach opens up conceptual and methodological areas of research which will allow the construction of a new type of scale. Depression scales should be constructed with two time dimensions: past and present; ill-being scales only refer to the present and QOL scales should have two time dimensions: present and future. It would be possible to combine these three scales into a single scale with three dimensions. Such a scale would enable depression and ill-being to be quantified, accurately diagnosed and monitored. The relative importance of principal symptoms could be assessed, facilitating the choice of therapy and follow-up methods.