Effects of Booster Sessions on Depression Vulnerability Following Cognitive Control Training

Evaluating the Effects of Personalized Booster Sessions on Depression Vulnerability Following Cognitive Control Training for Remitted Depressed Individuals

The current study aims to examine the impact of booster sessions of cognitive control training (CCT) on indicators of depression vulnerability. Remitted depressed individuals (RMD) will be randomized over two groups, each receiving 10 sessions of the adaptive Paced Auditory Serial Addition Task, a well-established CCT procedure (Koster et al., 2017; Siegle et al., 2007). During and following completion of the training procedure, functioning will be monitored on a weekly basis over a period of 15 weeks. During this period, one group will be offered booster sessions based on early warning signs for possible recurrence of depression, whilst the other group will not receive booster sessions.

Cognitive impairments are closely associated with depression and recent studies have found that these cognitive problems can persist following remission of depression. Internet-delivered cognitive control training (CCT), and the adaptive Paced Auditory Serial Addition Task (aPASAT) in particular, has shown to be an effective preventative intervention for remitted depressed individuals (RMD), where beneficial effects have been found for rumination, depressive symptomatology (Hoorelbeke & Koster, 2017), and risk for recurrence of depression (Hoorelbeke et al., 2021). At the same time, prior studies suggest significant heterogeneity in response to CCT, where RMD individuals can show strong fluctuations in functioning in the months following completion of aPASAT training. In line with this, recent findings suggest that, for individuals with high-risk profiles, initial training gains may diminish over time, resulting in recurrence of internalizing symptomatology (Hoorelbeke et al., 2022). As such, there may be merit in the use of CCT booster sessions. Currently, it is unclear whether offering additional CCT sessions when RMD individuals are reporting increased symptomatology (i.e., adding booster sessions based on early warning signs for possible recurrence of depression) can increase the long-term effectiveness of CCT. In this study, two groups of RMD individuals will perform 10 CCT sessions, after which one group will be offered booster sessions (contingent on indicators of functioning). For this purpose, we will rely on 15 weekly mobile assessments, using the PHQ-9 questionnaire. In addition, functioning will be assessed using a more extensive assessment battery at baseline, post-training (2 weeks after baseline) and follow-up (15 weeks after baseline).

The CCT training group without booster sessions will receive 10 training sessions with the Adaptive Paced Auditory Serial Addition Task (aPASAT). The 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.

The CCT with booster sessions group will receive 10 training sessions with the Adaptive Paced Auditory Serial Addition Task (aPASAT). After these training sessions, participants in this condition will be asked to complete additional CCT sessions after reporting two consecutive assessments of increased depressive symptoms during the monitoring period (PHQ-9 scores equal or greater to 9). Specifically, they will then be instructed to perform three additional sessions within one week. This may be repeated when the participant reports multiple consecutive assessments of increased depressive symptoms during the post-training phase, with a minimum of 3 weeks between the booster sessions and a maximum of 9 boosters (3 x 3 sessions) in total.

Self-report questionnaire measuring depression symptomatology, with higher scores indicating more severe depression symptoms.

Self-report questionnaire measuring depression symptomatology, with higher scores indicating more severe depression symptoms.

Change from baseline in repetitive negative thinking. The PTQ-NL consist of 15 items which are rated from 0 (never) to 4 (almost always). Lower scores indicate lower levels of repetitive negative thinking.

Self-report measure for emotion regulation: a 36-item questionnaire, consisting of adaptive and maladaptive emotion regulation strategies. Each item is rated on a 1 to 5 scale (1 = almost never and 5 = almost always).

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

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).

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.

The 6-item WPAI measures the effect of health problems on the ability to work and carry out daily activities.

In the LTE questionnaire, unpleasant 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. This questionnaire is included to be able to check for occurrence of life events during the intervention- and follow-up period.

Inclusion Criteria: History of ≥ 1 depressive episode(s) Currently in remission (≥ 3 months) Access to a computer with an internet connection Access to a smartphone 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