Blood-brain barrier water permeability across the adult lifespan: A multi-echo ASL study.
Level 4 - case-series / case-control
Cross-sectional observational imaging study
PubMed 39798256 · doi:10.1016/j.neurobiolaging.2024.12.012
What was done
Evaluated blood-brain barrier (BBB) permeability using the time of exchange (Tex) of water measured by non-invasive multi-echo arterial spin labeling (ASL) MRI. The authors assessed Tex, cerebral blood flow (CBF), and arterial transit time (ATT) across gray matter (GM), white matter (WM), and cerebral lobes in 209 healthy adults aged 26 to 87 years (194 included in main analyses after quality control) using general linear models stratified by age and sex.
What was found
Higher age was associated with higher BBB permeability (lower Tex) in females, with Tex decreasing by 0.47 ms per year in GM (p < 0.05) and by 0.49 ms per year in WM, but no significant association was observed in males. The largest regional change occurred in the frontal lobes (0.64 ms decrease per year, p = 0.011). GM CBF decreased with age by -0.71 mL/min/100g per year in females (p < 0.001) and -0.31 mL/min/100g per year in males (p < 0.05). After adjusting Tex models for CBF and ATT, the age effect on Tex disappeared in GM and was not statistically significant in WM (β = -0.28, p = 0.08).
Why it matters
This study provides normative reference data for non-invasive BBB water permeability across the adult lifespan and demonstrates that hemodynamic parameters like CBF and ATT strongly confound apparent age-related BBB alterations.
Limits
The cross-sectional design cannot assess longitudinal within-person changes over time. The primary age effect in gray matter disappeared after adjusting for hemodynamic covariates, and the abstract omits exact confidence intervals and detailed health screening parameters.
Cited by
- supports The blood-brain barrier naturally becomes less functional and increasingly permeable as humans age.