Background. Although there is good evidence that cognitive therapy (CBT) lessens relapse and recurrence in unipolar depression, the duration of this effect is not known.
Method. One hundred and fifty-eight subjects, from a randomized controlled trial of CBT plus medication and clinical management versus medication and clinical management alone, were followed 6 years after randomization (4½ years after completion of CBT) and the longitudinal course assessed.
Results. Effects in prevention of relapse and recurrence were found to persist, with weakening, and were not fully lost until 3½ years after the end of CBT. Residual symptoms were also lessened.
Conclusions. The effect of CBT in reduction of relapse and recurrence persists for several years. The potential value of subsequent additional CBT some time after cessation should be explored.