RECOVERY FROM DEPRESSIVE-ILLNESS DOES FIT AN EXPONENTIAL MODEL

A very large number of therapeutic trials of antidepressant drugs have been reported in the scientific literature. Until now, the comparison of one drug with another, or with placebo, has been performed typical ly by comparing the scores on depression rating scales of the two grou ps of patients at fixed points of time after the beginning of therapy. It was postulated in 1989 that the curves of the recovery scores foll owed an exponential curve of the formula y = ae(-bx) + c. This hypothe sis was tested in a double-blind controlled trial of the antidepressan t minaprine, with the nse of the scores on the Hamilton Bating Scale f or Depression (HAM-D). We found that the correlation coefficient, Pear son's r, between the log of the HAM-D value and the meek number of the study was -0.99. This gives a coefficient of determination of 0.98, w hich makes it clear that the model adequately fits the data We conclud e that the use of the formula gives a method of testing the statistica l significance of the difference between treatments as a valuable alte rnative to traditional tests. We believe that this would give a much m ore sensitive discrimination between treatments because all of the dat a points are used to calculate a single parameter - the slope of the c urve.