What this means
The glymphatic system supports brain homeostasis by facilitating perivascular fluid transport and metabolic waste clearance. Diffusion-tensor imaging along the perivascular space (ALPS-index) provides a non-invasive surrogate marker of glymphatic activity.
A plain-English summary is on its way. Until then, this is the start of the authors' own summary.
- Who it was tested in
- Not stated
- Kind of research
- A study
The science
- Original title
- Reduced perivascular diffusion in multiple sclerosis is associated with aging, disease duration, and mobility impairment.
- Authors
- Sato SD, Richmond SB, Fling BW et al.
- Journal
- Multiple sclerosis and related disorders
- Published
- Oct 19, 2026
- Study type
- Study
- PMID
- 42896342 ↗
Abstract
Background
The glymphatic system supports brain homeostasis by facilitating perivascular fluid transport and metabolic waste clearance. Diffusion-tensor imaging along the perivascular space (ALPS-index) provides a non-invasive surrogate marker of glymphatic activity. The objectives of this study were to: (1) compare the ALPS-index between individuals with relapsing-remitting MS (RRMS) and non-MS controls, (2) examine the role of age in the association between ALPS-index and disease duration, and (3) examine the relationship between ALPS-index and walking speed in RRMS.
What they did
Individuals with RRMS and age‑ and sex-matched controls underwent 3T MRI, including diffusion‑weighted imaging. ALPS‑index was calculated using standardized regions of interest. Walking function was assessed using a two‑minute walk test.
What they found
Individuals with RRMS have significantly lower ALPS‑index compared to controls (p = 0.001). Across participants, older age was associated with lower ALPS‑index (p < 0.001), with no evidence that age effects differed by group (group effect: p = 0.311, group x age: p = 0.954). In RRMS, a lower ALPS‑index was associated with longer disease duration (p = 0.028); however, mediation analyses showed that chronological age largely explained this relationship (p = 0.012). In a multivariable model, both lower ALPS‑index and slower gait speed were independently associated with longer disease duration, with an interaction effect (p = 0.032) suggesting functional compensation between perivascular diffusion and mobility. These findings highlight the interconnected roles of aging, perivascular fluid transport, and mobility in MS and support the ALPS‑index as a feasible, non‑invasive imaging marker of age‑related vulnerability.
The authors' abstract, grouped under plain headings from its own section labels.
Sato SD, Richmond SB, Fling BW et al. Reduced perivascular diffusion in multiple sclerosis is associated with aging, disease duration, and mobility impairment. Multiple sclerosis and related disorders. 2026. doi:10.1016/j.msard.2026.107958. PMID: 42896342. https://pubmed.ncbi.nlm.nih.gov/42896342/