We have read with interest a recent paper by Tian et al., which investigated the impact of body mass index (BMI) on the glymphatic system function in patients with Parkinson’s disease (PD) (1). The authors used the diffusion tensor imaging analysis along the perivascular space (DTI-ALPS) method to obtain the ALPS index as a proxy for glymphatic system activity. They found that PD patients with higher BMI exhibited a reduced ALPS index, and the ALPS index in patients with obesity was statistically significantly lower than that in patients with normal weight. Furthermore, a significant negative correlation between the ALPS index and BMI was found among the PD patients in the study.
In this letter, we aim to broaden the discussion by proposing the potential role of obstructive sleep apnea (OSA) as a mediator in the relationship between glymphatic function and BMI. Previous research has demonstrated that glymphatic activity is significantly enhanced during sleep (2). Subsequent research has suggested that the efficiency of glymphatic clearance depends on sleep depth, with reductions in deep sleep, frequent interruptions during lighter sleep stages, and shorter total sleep duration all contributing to impaired glymphatic function (3,4). This dependency on both sleep quality and quantity has also been observed specifically in PD populations (5-7).
This perspective is particularly relevant given that sleep was not assessed in the original study by Tian et al., leaving open the possibility that undiagnosed or unaccounted for sleep disturbances may have contributed to the observed association. OSA, as a well-established disruptor of sleep (8) and a condition closely associated with elevated BMI (9), is therefore of particular interest. Supporting this notion, it is noteworthy that Lee et al. identified a link between glymphatic function and OSA (10). Similarly, our recent work has demonstrated an association between glymphatic dysfunction and OSA in individuals with early-stage PD (11). Based on these findings, we propose that OSA may, at least in part, mediate the observed relationship between glymphatic function and BMI.
We believe that considering OSA in this context may offer a more comprehensive understanding of the complex interplay between obesity and glymphatic function.
Supplementary
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Acknowledgments
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Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved.
Footnotes
Funding: None.
Conflicts of Interest: Both authors have completed the ICMJE uniform disclosure form (available at https://qims.amegroups.com/article/view/10.21037/qims-2025-1124/coif). The authors have no conflicts of interest to declare.
References
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