Sleep disturbances and language function impairment in the elderly: Evidence of limbic and prefrontal tracts involvement

Background Although poor sleep is widely assumed to impair cognitive function, the impact of sleep disturbances (SD) on language function and the underlying mechanisms of this relationship remains unclear. Objective This study aimed to investigate the association between SD and language function in non-demented elderly individuals, identify potential neuroimaging correlates, and analyze risk factors for SD. Methods We analyzed 784 non-demented elderly subjects from the Alzheimer's Disease Neuroimaging Initiative (ADNI), categorized into SD (n = 256) and normal sleep groups (n = 528) based on self-reported sleep status. Cognitive differences were assessed, and the findings were validated using the China Longitudinal Aging Study (CLAS) and the Chinese Longitudinal Healthy Longevity Survey (CLHLS). Diffusion tensor imaging (DTI) metrics were correlated with language function, and SD risk factors were examined. Results In the ADNI cohort, elderly individuals with SD exhibited worse language function compared to those with normal sleep, and this finding was validated in the CLAS and CLHLS cohorts. Meanwhile, the decline in longitudinal language function among elderly individuals with SD occurred at a faster rate. Differences in DTI metrics between the two groups were primarily observed in the limbic and prefrontal regions. Finally, the risk factors for elderly with SD mainly included years of education, physical and emotional conditions, lifestyles, living environment, and parental survival status. Conclusions SD correlates with language impairment in non-demented elderly, possibly due to limbic/prefrontal tract damage. Risk factors encompass demographic, health, lifestyle, and socio-environmental aspects. Effectively managing these factors and treating SD may improve language function.