Optimal Dose of a Cognitive Control Training for Depression Vulnerability

Establishing a Dose-response Relationship for the Effects of a Cognitive Control Training on Depression Vulnerability

This study aims to examine the dose-response relationship of an online adaptive cognitive control training on depressive symptomatology and rumination. Participants will be randomized over six groups, each receiving a different dose (0, 1, 5, 10, 15 or 20 sessions) of a cognitive control training in remitted depressed patients. An adaptive Paced Auditory Serial Addition Task will be used as cognitive control training.

Depression is often associated with cognitive impairments and recent studies have found that for some people, these cognitive problems persist after remission of depression. These cognitive impairments could be a risk factor for recurrence of depressive episodes. Cognitive control training aims to address these cognitive impairments and decrease the risk of recurrence of depression. One promising operationalization of cognitive control training is the adaptive Paced Auditory Serial Addition Task, but currently, it's unclear how many sessions one should complete in order to obtain cognitive- and emotional transfer effects. By comparing multiple groups with a different number of sessions (0, 1, 5, 10, 15 and 20), with measures at post (one month after baseline) and two follow-up periods (at 3 months and 6 months after baseline), this study examines the effects of an online cognitive control training on depressive vulnerability factors.

Cognitive control training: The adaptive Paced Auditory Serial Addition Task (aPASAT) is a Cognitive Control Training where participants need to click on the sum of the last two heard digits. Task difficulty is modified based on the participants' current task performance, allowing training of cognitive control. Five intervention groups will each receive a different amount of sessions.

Waitlist control group: Participants randomized to the control group will not perform the cognitive control training during the study, but will be given the opportunity to follow the training afterwards.

The five intervention groups will receive either 1, 5, 10, 15 or 20 training sessions with the Adaptive Paced Auditory Serial Addition Task (aPASAT).

Self-report questionnaire with 21 items, depression symptom severity, scores can range from 0 to 63, with higher scores indicating more severe depression.

baseline, post training (one month after baseline), 3 month follow-up after baseline, 6 month follow-up after baseline

Change from baseline in perseverative thinking. The PTQ-NL consist of 15 items and are assessed using scores ranging from 0 (never) to 4 (almost always). Lower scores indicate lower levels of preservative thinking.

baseline, post training (one month after baseline), 3 month follow-up after baseline, 6 month follow-up after baseline

Self-reported measure for emotion regulation: a 36-item questionnaire, consisting of 9 subscales (Self-blame, Other-blame, Rumination, Catastrophizing, Putting into Perspective, Positive Refocusing, Positive Reappraisal, Acceptance and Planning). Each item is rated on a 1 to 5 scale (1 = almost never and 5 = almost always). Higher subscale scores represent more frequent use of a specific cognitive strategy.

baseline, post training (one month after baseline), 3 month follow-up after baseline, 6 month follow-up after baseline

baseline, post training (one month after baseline), 3 month follow-up after baseline, 6 month follow-up after baseline

The Burnout Assessment Tool (BAT) is used to assess burn-out risk. The score ranges from 1 to 5, with higher scores indicating a higher risk of burn-out.

baseline, post training (one month after baseline), 3 month follow-up after baseline, 6 month follow-up after baseline

The Remission from Depression Questionnaire has 41 items, which assess domains such as positive mental health, life satisfaction, and sense of well-being. The items are scored 0 (not at all or rarely true), 1 (sometimes true) or 2 (often or almost always true).

baseline, post training (one month after baseline), 3 month follow-up after baseline, 6 month follow-up after baseline

A non-adaptive computerized version of the Paced Auditory Serial- Addition Task (PASAT) was used as a measure of participants' working memory abilities. Higher accuracy scores suggest greater cognitive control resources.

baseline, post training (one month after baseline), 3 month follow-up after baseline, 6 month follow-up after baseline

The n-back task is a classic cognitive working memory task during which participants are asked to decide if a digit appearing on a screen is the same as the digit that appeared n stimuli earlier (n-back).

In the LTE questionnaire, unpleased life events are listed and participants are asked if these events occurred recently. The LTE-Q contains 13 items for which "yes" or "no" are the two possible answers.

The 6-item CEQ measures ratings of treatment credibility, acceptability/satisfaction, and expectations for success.

Inclusion Criteria: History of ≥ 1 depressive episode(s) Currently in remission (≥ 3 months) Access to a computer with an internet connection Exclusion Criteria: Ongoing depressive episode Psychotic disorder (current and/or previous) Neurological impairments (current and/or previous) Excessive substance abuse (current and/or previous) Use of antidepressant medication is allowed if kept at a constant level