Links between nocturnal hypoxia and cognitive function in breast cancer.

Cognitive complaints are common in breast cancer (BC). Previous studies have linked sleep-disordered breathing (SDB) to cognitive decline in the general population, highlighting hypoxia as a key factor in cognitive decline severity. This link is understudied in BC patients. We investigated the association between nocturnal hypoxia and cognitive performance in 35 BC patients compared to 21 healthy controls (HC; mean ages: 61.6 ± 5.3 and 62.6 ± 4.3, respectively) using in-home ambulatory polysomnography, including oximeter to record oxygen saturation. All participants completed questionnaires and cognitive tests. Non-parametric Wilcoxon tests were conducted to compare the two groups and multivariable models to measure the association between hypoxia and cognitive performance, adjusting for anxiety and depression. Our results showed more frequent nocturnal hypoxia and more cognitive complaints in BC patients compared to HCs (p < 0.05). However, cognitive tests did not show significant impairment in the BC group, and no significant association was found between nocturnal hypoxia and cognitive performance. Our patients were treated with radiotherapy and/or endocrine therapy, but without chemotherapy, which may explain their normal cognitive scores despite subjective cognitive complaints. Nocturnal hypoxia is more prevalent in BC patients than in HCs, but it may not be the primary factor influencing cognitive performance in this population.Trial registration: NCT03420105, registered: January 10, 2018.