Intervention Targeting Depressive Symptoms and Mental Rumination

This study aims to investigate the combine effects of Behavioral Activation and Attention Training on depression, well-being and other processes involved in depression as rumination.

A multiple baseline design is followed with multiple idiographic assessments, in addition to a pre-post and follow-up standardized assessment design.

Major depressive disorder (MDD) is one of the most prevalent mental disorders, as well as one of the leading causes of disability worldwide. Behavioral activation is an empirically validated treatment for depression associated with medium effect size. The rationale of behavioral activation is to increase activation and reduce avoidance in order to reduce depressive affects. In parallel, Attention Training Techniques (ATT) is also an empirically validated treatment for depression. The rationale of ATT is to attenuate the self-focused attention and increase flexible attentional control over information processing to reduce depressive affects. ATT could target specific cognitive factors that are not changed through traditional interventions, and might enhance treatment outcomes for clinical and subclinical depressed when used in adjunct to psychotherapy. Then, the use of ATT may be a promising avenue to increase effectiveness of behavioral activation treatment.

The aims of the study are multiple. First, to measure the treatment feasibility and adherence of different treatment combinations and to measure it throughout the study. Second, to investigate the efficacy of Behavioral Activation Therapy for Depression combined with Attention Training sessions in subclinical and clinical depressed participants. Third, to investigate the mechanisms of change of both interventions.

The design will follow an "A1-B-A2'" design. Daily ideographic measures will be collected during all phases. Phase A1 and A2 are non-interventional phases of baseline and follow-up period respectively. Participants are randomly allocated to baseline lengths of 7, 10 and 15 days. Phase B is the intervention phase ranging from 5 weeks to 7 weeks. Three conditions exist with participants randomly allocated to one of these conditions. The intervention is provided in individual once a week. The first condition is a combination of 5 weeks of behavioral activation treatment for depression (BATD) and Attention Training technique (ATT)(2 hours/week). The second condition is 3 weeks of ATT followed by 5 weeks of BATD (1 hour/week), and the third is 5 weeks of BATD followed by 3 weeks of ATT (1 hour/week). Nomothetic standardized measures were also collected at pre-treatment (T0), after treatment (T1), after two weeks (T2) and 3 months later (T3).

The investigators hypothesized that the three proposed conditions will have an effect on the following target variables: activation, avoidance, reward motivation, self-focused attention, awareness as well as on transfer measures: depressive symptoms, rumination, anhedonia, well-being, social and work impairments, and cognitive control (2) changes in the target variables should preceded changes in the transfer measures (3) the therapeutic effects would be greater and faster when the treatments are combined than when they are offered sequentialy (i.e., in condition 1 versus conditions 2 and, (4) the therapeutic effect observed in Phase B was maintained in follow-up.

Target measures were expected to change with the introduction of intervention in comparison to baseline phase. In Condition of combination, the investigators expected to observe in Phase B an enhancement of activation, awareness and reward motivation and a decrease in avoidance and self-focused attention in comparison to the baseline phase. In Condition 2 with ATT sessions followed by BA sessions, the investigators expected to observe a reduction of self-focus attention, and an enhancement of awareness with the introduction of ATT, and an enhancement of activation and reward motivation and a reduction of avoidance with the introduction of BA. In Condition 3 with BA sessions followed by ATT sessions, the investigators expected the opposite pattern of change with first an enhancement of activation and reward motivation and a reduction of avoidance with the introduction of BA in comparison to baseline and then a reduction of self-focus attention, and an enhancement of awareness with the introduction of ATT in comparison to baseline.

Eligibility Criteria:
Inclusion Criteria:

* good understanding of French,
* at least a medium level of depressive symptoms
* report the presence of abstract rumination that generates negative mood.

Exclusion Criteria:

* Having a history of psychotic disorder
* Having a history of Bipolar disorder,
* Having a history of severe brain trauma or epilepsy
* with a moderate or severe substance use disorder other than tobacco (according to the DSM-V; i.e., showing 4 or more symptoms
* with an organic illness (e.g. cancer),
* with a concurrent additional psychotherapy,
* with acute suicidal ideation,
* with evidence of a significant change in medication within one month prior to baseline assessment.