Editors' Note: Association of Sleep, Neuropsychological Performance, and Gray Matter Volume With Glymphatic Function in Community-Dwelling Older Adults

Abstract

Dr. Siow et al. explored the associations between human glymphatic function—assessed using diffusion tensor imaging analysis along the perivascular space (DTI-ALPS) index—with sleep, neuropsychological performance, and cerebral gray matter volumes in a cross-sectional study of 84 participants aged 60 years or older. They found that age, N2 stage sleep duration, and apnea-hypopnea index were independently associated with DTI-APLS and that higher DTI-APLS was associated with better neuropsychological test performance and higher gray matter volume, implying that DTI-APLS may be a potential biomarker for cognitive disorders. Nonetheless, the reproducibility of this new MRI technique to assess interstitial fluid dynamics remains under investigation. In response, Dr. Kawada seeks to clarify the selection of independent variables for the multivariable models presented in the paper. Responding to these comments, the authors note that among baseline demographic and clinical variables, only age and pulse rate had a significant association with DTI-APLS. They also report the adjusted R2 of the model as requested by Dr. Kawada. The glymphatic system has emerged as an important frontier in the study of sleep, cognition, and neurodegenerative diseases, and we can expect to see further insights from in-vivo glymphatic imaging in the coming years. Dr. Siow et al. explored the associations between human glymphatic function—assessed using diffusion tensor imaging analysis along the perivascular space (DTI-ALPS) index—with sleep, neuropsychological performance, and cerebral gray matter volumes in a cross-sectional study of 84 participants aged 60 years or older. They found that age, N2 stage sleep duration, and apnea-hypopnea index were independently associated with DTI-APLS and that higher DTI-APLS was associated with better neuropsychological test performance and higher gray matter volume, implying that DTI-APLS may be a potential biomarker for cognitive disorders. Nonetheless, the reproducibility of this new MRI technique to assess interstitial fluid dynamics remains under investigation. In response, Dr. Kawada seeks to clarify the selection of independent variables for the multivariable models presented in the paper. Responding to these comments, the authors note that among baseline demographic and clinical variables, only age and pulse rate had a significant association with DTI-APLS. They also report the adjusted R2 of the model as requested by Dr. Kawada. The glymphatic system has emerged as an important frontier in the study of sleep, cognition, and neurodegenerative diseases, and we can expect to see further insights from in-vivo glymphatic imaging in the coming years.