Reductions in sleep quality and circadian activity rhythmicity predict longitudinal changes in objective and subjective cognitive functioning in women treated for breast cancer

Purpose To examine long-term cognitive effects of chemotherapy and identify predictors among women with breast cancer (WBC). Patients and methods Sixty-nine WBC scheduled to receive chemotherapy, and 64 matched-controls with no cancer, participated. Objective and subjective cognition, total sleep time, nap time, circadian activity rhythms (CAR), sleep quality, fatigue, and depression were measured pre-chemotherapy (Baseline), end of cycle 4 (Cycle-4), and one-year post-chemotherapy (1-Year). Results WBC showed no change in objective cognitive measures from Baseline to Cycle-4 but significantly improved from both time points to 1-Year. Matched-controls showed an increase in test performance at all time points. WBC had significantly higher self-reported cognitive dysfunction at Cycle-4 and 1-Year compared to baseline and compared to matched-controls. Worse neuropsychological functioning was predicted by less robust CARs (i.e., inconsistent 24 h pattern), worse sleep quality, longer naps, and worse cognitive complaints. Worse subjective cognition was predicted by lower sleep quality and higher fatigue and depressed mood. Conclusion Objective testing showed increases in performance scores from pre- and post-chemotherapy to one year later in WBC, but matched-controls showed an increase in test performance from baseline to Cycle-4 and from Cycle-4 to 1-Year, likely due to a practice effect. The fact that WBC showed no practice effects may reflect a form of learning deficit. Compared with the matched-controls, WBC reported significant worsened cognitive function. In WBC, worse objective and subjective cognitive functioning were predicted by worse sleep and sleep-related behaviors (naps and CAR). Interventions that target sleep, circadian rhythms, and fatigue may benefit cognitive function in WBC.

Automated summary

Objective cognitive performance improved in women with breast cancer (WBC) from pre- to post-chemotherapy to one year later, while matched-controls showed consistent improvement throughout all time points. WBC reported significantly worse cognitive function compared to controls. Poorer neuropsychological functioning in WBC was predicted by inconsistent circadian activity rhythms, poor sleep quality, longer nap times, and cognitive complaints. Worse subjective cognition was predicted by lower sleep quality, higher fatigue, and depressed mood. Interventions targeting sleep, circadian rhythms, and fatigue may benefit cognitive function in WBC.