Abstract
PurposeTo examine long-term cognitive effects of chemotherapy and identify predictors among women with breast cancer (WBC).Patients and methodsSixty-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).ResultsWBC 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.ConclusionObjective 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.
Highlights
Chemotherapy can produce reports of acute cognitive dysfunction [1,2,3] with one-third of patients with cancer reporting long-term impairment lasting up to five years or more [1, 3]
The current study explored whether decreases in robustness of circadian activity rhythms (CAR) and sleep quality and increases in fatigue predict decreases in cognitive functioning, as these factors have been predictive of other outcomes in cancer, including survival [20], quality of life (QOL) [20, 21], and markers of cancer progression [22]
with breast cancer (WBC) showed significantly worse sleep, increased fatigue, more depressive symptoms, and more disrupted CARs compared to their own baseline levels and to matched-controls at cycle 4 (Cycle-4)
Summary
Chemotherapy can produce reports of acute cognitive dysfunction [1,2,3] with one-third of patients with cancer reporting long-term impairment lasting up to five years or more [1, 3]. Those receiving high-dose chemotherapy or concurrent cytotoxic agents have more cognitive disruption than those on standard doses [4, 5]. The deleterious cognitive effects, both objective and subjective, persist even after adjusting for variance attributable to depression, age, education, and premorbid IQ [6, 7]. Cognitive dysfunction is rarely diagnosed or addressed in patients with cancer
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