The relationship between insomnia and cognitive impairment in breast cancer survivors

Abstract

Background: Cancer-related cognitive impairment is an emerging public health burden. Growing research suggests that sleep disturbances contribute to poor cognition. Our study aimed to evaluate the association between insomnia and cognitive impairment in breast cancer survivors. Methods: We analyzed cross-sectional data from a cohort study of postmenopausal women with stage 0-III hormone receptor-positive breast cancer on aromatase inhibitor therapy. The study was conducted between November 2011 and April 2015 at an academic cancer center (Philadelphia, PA). Insomnia was assessed with the Insomnia Severity Index. Perceived cognitive impairment was assessed with the cognitive subscale of the Breast Cancer Prevention Trial Symptom Checklist. We used linear regression to evaluate the association between insomnia and perceived cognitive impairment. Results: Among 1072 patients, 556 (51.9%) reported insomnia and 847 (79.0%) were bothered by cognitive symptoms (forgetfulness, difficulty concentrating, distractibility). Greater perceived cognitive impairment was reported by patients with mild insomnia (regression coefficient [β] = 0.35, 95% confidence interval [CI] = 0.23 to 0.46, P < .001), moderate insomnia (β = 0.51, 95% CI = 0.36 to 0.65, P < .001), and severe insomnia (β = 0.94, 95% CI = 0.67 to 1.21, P < .001), compared with those without insomnia. Greater perceived cognitive impairment was also associated with patients younger than 55 years (β = 0.30, 95% CI = 0.15 to 0.45, P < .001), taxane-based chemotherapy (β = 0.11, 95% CI = 0.004 to 0.22, P = .04), anxiety (β = 0.47, 95% CI = 0.30 to 0.64, P < .001), and depression (β = 0.65, 95% CI = 0.35 to 0.94, P < .001). Conclusions: Among postmenopausal breast cancer survivors receiving aromatase inhibitor therapy, insomnia and cognitive impairment are prevalent and characterized by a graded association, in which severity of perceived cognitive impairment increases as insomnia severity increases. Our findings warrant further research to determine whether addressing sleep is a strategy to improve management of cancer-related cognitive impairment.