Does Cognitive-Behavioral Therapy for Insomnia Improve Self-reported Cognitive Functioning in Breast Cancer Survivors Experiencing Sleep Disturbances?

Purpose: The symptom cluster of sleep disturbance, fatigue, and cognitive impairment is common in breast cancer (BC) survivors with a long-term prevalence of approximately 40%. Previously, we have shown that internet-delivered and fully automated cognitive-behavioral therapy for insomnia (iCBT-I) is an effective intervention for sleep disturbances in women treated for breast cancer. Here we present results of secondary analyses of the effects of iCBT-I on self-reported cognitive functioning. Methods: A total of 255 Danish BC survivors (age=53.2, SD=8.8) experiencing sleep disturbances (Pittsburg Sleep Quality Index (PSQI)>5) were recruited and randomly allocated to iCBT-I (n=133) or waitlist control (n=122). Participants responded to questionnaires at baseline and post-intervention. Self-reported cognitive functioning was assessed with The Cognitive Failures Questionnaire (CFQ), a 25-item questionnaire assessing three different cognitive factors related to distractibility, forgetfulness, and false triggering. Results: A total of 203 participants completed questionnaires at both baseline and post-intervention. Statistically significant time × group interactions (p ≤ 0.02) were found for all sleep-related outcomes from pre- to post-intervention with small to large effect sizes (Cohen’s d= 0.33-1.17). Within-group analyses revealed no improvements on any of the cognitive factors from baseline to follow-up in the intervention group (p’s= 0.20-0.62). Furthermore, no between-group differences across time (time x group interaction) were observed (p’s>0.09). Conclusions: No evidence was found for improvements on self-reported cognitive functioning following an internet-delivered CBT-I intervention in a Danish cohort of BC survivors with sleep disturbances.