Efficacy of an internet-delivered cognitive enhancement intervention for subjective residual cognitive deficits in remitted major depressive disorder: A randomized crossover trial

Background: Cognitive deficits such as difficulties with attention, memory, and executive functions are frequently reported during remission from depression and relates to adverse functioning in daily life and risk of relapse. There is therefore a need for interventions targeting cognitive deficits after depression. However, few randomized controlled trials have investigated the efficacy of interventions targeting subjective residual cognitive deficits in adults remitted from depression. Methods: This randomized crossover trial aimed to investigate the efficacy of an internet-delivered cognitive enhancement intervention on subjective residual cognitive deficits. Forty-four formerly depressed adults (89 % female;mean age = 39 years) were included. Twenty-three participants received the intervention, and 21 participants were assigned to a waitlist control group. The waitlist control group received the intervention after seven weeks. Analyses of follow-up assessment after six months were conducted for the combined sample. Results: Significant differences were found between the intervention and waitlist control group in subjective cognitive functioning (d = 1.83) and rumination (d = 1.65). There was a difference in symptoms of depression between the groups (d = 1.22), whereas symptoms of depression increased in the waitlist control, but not in the intervention group. Fewer participants in the waitlist control group (43 %), compared to the intervention group (78 %) showed reliable improvement in self-reported cognitive deficits after receiving the intervention. Limitations: Findings should be interpreted with caution due to the small sample, and lack of an active control group. Conclusions: Internet-delivered cognitive enhancement interventions may improve subjective cognitive deficits. Waiting time to receive cognitive enhancement interventions may worsen symptoms and treatment response.