Background: Depression is a common and serious problem in older adults, but few have access to psychological treatments. Internet-delivered Cognitive Behavioral Therapy (ICBT) has the potential to improve access and has been found to be effective in adults with depression. The aim of this study was to examine the effects of tailored ICBT for depression in older adults aged 65 years or older. We also investigated if cognitive flexibility could predict outcome.

Methods: Following online recruitment from the community, included participants were randomly allocated to either ten weeks of clinician guided ICBT (n = 50) or to an active control group in the form of non-directive support (n = 51). Primary depression outcome was the Geriatric Depression Scale (GDS-15). Several secondary outcomes were used, such as the Beck Depression Inventory (BDI-II) and the Patient Health Questionnaire (PHQ-9).

Results: Both treatment and active control groups significantly reduced their levels of depression, and the treatment group showed significantly greater improvement on the GDS-15 and BDI-II, but not on the PHQ-9. Between-group effect sizes as Cohen's d were 0.78 (CI95% 0.36-1.20) on the GDS-15 and 0.53 (CI95% 0.11-0.94) on the BDI-II.

Conclusions: Tailored ICBT is superior to an active control for older adults with depression. Between-group effects were smaller than in previous RCTs, most likely because of the use of an active control condition. Cognitive flexibility did not predict outcome. We conclude that ICBT can be used for older adults with depression, and thus increase access to psychotherapy for this group.

Trial registration: This trial was retrospectively registered in clinicaltrials.gov (no. NCT05269524) the 8th of March 2022.