Modeling the recovery from depressive illness by an exponential model withmixed effects

In clinical trials of antidepressant treatments, a depression rating score is usually measured at several points of time for each patient. We propose an approach to fit data from this type of clinical trial using an exponenti al mixed-effects model. Compared to previous proposals, this approach has t he advantage that individual recovery curves are fitted rather than curves of means. Furthermore, no artificial fixing of model parameters is needed a s in other approaches. The flexibility of the proposed model is shown for v arious situations. The approach is illustrated by an example from a placebo -controlled study for the treatment of depression with St. John's Wort (Hyp ericum perforatum).