Psychotherapy for residual depression following initial treatment: effectiveness, relapse prevention and mechanisms of change

Although psychotherapy and antidepressants seem to help initially, many
depressed patients suffer from relapse and recurrence. Recent findings suggest
cognitive behaviour therapy (CBT) may reduce that risk in the long-term, but
the mechanisms of change that prevent relapse and recurrence are still unknown.
We will be the first to study the effectiveness of CBT compared to
interpersonal therapy (IPT) for residual depression after initial treatment
(reduction of symptoms; prevention of relapse and recurrence) and the
underlying mechanisms of change (explicit and implicit measures).

To compare the effectiveness of CBT versus IPT in the prevention of future
relapse among residually depressed patients who received initial treatment. Our
research questions: Are CBT and IPT following initial treatment effective
interventions that prevent relapse or recurrence of depression in the
long-term? What are the underlying psychological mechanisms of change in CBT,
compared to IPT? Do genetic variations in polymorphisms modify the short and
long-term efficacy of CBT and IPT?

Randomized trial with three groups: CBT (n=75), IPT (n=75) and an 8-week
waitinglist condition (n=30)

Cognitive behaviour therapy (CBT) and interpersonal therapy (IPT). CBT and IPT
will be offered at our clinical site (Riagg Maastricht). Both interventions are
written out in a treatment manual, will be delivered by qualified therapists
and will both contain 18 sessions and two booster sessions.

Participants will have to visit the research centre twice, and will spend
approximately 20 hours filling out questionnaires or being interviewed over the
course of 24 months. Part of the assessments is a clinical interview at the
beginning of the study and at the end of follow-up, and a computer task in an
observation laboratory. No risks are involved in participation.