Multidimensional diffusion–relaxation MRI mapped cellular-scale tissue architecture in cognitively unimpaired adults aged 23 to 77, showing that brain aging proceeds as a progressive reorganization of microstructure rather than uniform tissue loss. With advancing age, fine cellular barriers break down, extracellular space expands, and tissue heterogeneity increases across both gray and white matter, alongside signatures consistent with iron accumulation and myelin loss. These changes appear in people without cognitive impairment, placing them well upstream of measurable decline.
Key Points
- Cellular barriers break down and extracellular space expands with age
- Microstructural disorder increases before detectable atrophy or cognitive symptoms
- Imaging signatures track iron accumulation and myelin loss separately
Longevity Analysis
Structural deterioration of the brain becomes measurable decades before function declines, and the resolution now exists to observe it in living people without predefined compartment models. Loss of microscopic restriction and expanding extracellular space point toward compromised barrier integrity and waste clearance — processes tied to myelin maintenance, iron handling, and the regenerative capacity of neural tissue. For anyone tracking cognitive trajectory over time, these measures offer an earlier and more specific readout than volumetric imaging, shifting the intervention window from reactive to anticipatory.
Original published by Wiley Aging Cell, by Joon Sik Park, Eppu Manninen, Shunxing Bao, Bennett A. Landman, Yihong Yang, Dan Benjamini .