Behavioral Activation and Emotion-focused Interventions in the Treatment of Depression, A Single-case Study

Procedure The study will be carried out by the authors or experienced clinicians (master level students at the Psychotherapy program at the Karolinska Institute), recruiting and treating patients with recurring depression at a primary care unit in the Stockholm region. 7 patients will be treated during 15 weeks. The treatment will be carried out in a blended format with an internet-based treatment supported with therapist face-to-face sessions. The initial behavioural activation phase lasts up to 6 weeks followed by additional emotion focused interventions. The treatment is initiated by a therapist session, thereafter therapist sessions are planned approximately every 3rd week.

To be included in the study participants must meet diagnostic criteria for depression as their primary problem according to DSM-5 (Diagnostic and Statistical Manual), have basic reading and writing skills in Swedish, and not express acute suicidal ideation. Patients with concurrent co-morbid psychiatric problems are eligible for inclusion unless another psychiatric diagnosis is assessed as primary to depression. Patients will be recruited from the regular flow of patients who seek treatment for psychological problems in the selected clinic. If interested they will be contacted by the study therapists and screened and assessed for eligibility after signing an informed consent.

Participants meeting inclusion criteria and not exclusion criteria will be offered participation in the study, and randomized to one of the 7 baseline lengths.

Methodology/approach/data analysis The research question will be investigated using a multiple baseline single-case A-B design. A will be the baseline phase, varying between 7 and 14 days, assessing the pattern of depression, behavioral activation and difficulties in emotion regulation before the intervention. Phase B comprise behavioral activation and emotion focused interventions as the independent variable and makes it possible to evaluate the effect of treatment on the dependent variable depressive symptoms. The B-phase will last 15 weeks and include the full internet-based treatment supported with 5-10 face-to-face therapist sessions .

Single-case experimental design (SCED) is particularly useful when evaluating a novel treatment in a clinical context as it produces reliable results even with a small sample size. Also, it is particularly helpful for studying the details of how the intervention works for each individual patient, through detailed and repeated measures of several dependent variables and processes. It is recommended that the effect of the intervention is assessed in at least 3 individuals (1), however, we will recruit at least 7 participants to allow for higher statistical power and as a safety measure for drop out and missing data.