Related Experiment Video
Updated: Aug 14, 2025
3D Modeling of the Lateral Ventricles and Histological Characterization of Periventricular Tissue in Humans and Mouse
Published on: May 19, 2015
Adult lifespan maturation and degeneration patterns in gray and white matter: A mean apparent propagator (MAP) MRI
Mustapha Bouhrara1, Alexandru V Avram2, Matthew Kiely1
1Magnetic Resonance Physics of Aging and Dementia Unit, National Institute on Aging, NIH, Baltimore, MD 21224, USA.
Abstract:
The relationship between brain microstructure and aging has been the subject of intense study, with diffusion MRI perhaps the most effective modality for elucidating these associations. Here, we used the mean apparent propagator (MAP)-MRI framework, which is suitable to characterize complex microstructure, to investigate age-related cerebral differences in a cohort of cognitively unimpaired participants and compared the results to those derived using diffusion tensor imaging. We studied MAP-MRI metrics, among them the non-Gaussianity (NG) and propagator anisotropy (PA), and established an opposing pattern in white matter of higher NG alongside lower PA among older adults, likely indicative of axonal degradation. In gray matter, however, these two indices were consistent with one another, and exhibited regional pattern heterogeneity compared to other microstructural parameters, which could indicate fewer neuronal projections across cortical layers along with an increased glial concentration. In addition, we report regional variations in the magnitude of age-related microstructural differences consistent with the posterior-anterior shift in aging paradigm. These results encourage further investigations in cognitive impairments and neurodegeneration.
Insights
Mean apparent propagator (MAP)-MRI reveals distinct brain aging patterns. Older adults show white matter axonal degradation and gray matter changes suggesting altered neuronal and glial function, supporting the posterior-anterior shift in aging theory.
Area of Science:
- Neuroimaging
- Brain Aging Research
- Diffusion MRI
Background:
- Brain microstructure changes with age, impacting cognitive function.
- Diffusion MRI is key to studying these age-related microstructural associations.
- Mean apparent propagator (MAP)-MRI offers advanced characterization of complex brain microstructure.
Purpose of the Study:
- To investigate age-related cerebral differences using MAP-MRI.
- To compare MAP-MRI findings with diffusion tensor imaging (DTI).
- To explore specific MAP-MRI metrics like non-Gaussianity (NG) and propagator anisotropy (PA).
Main Methods:
- Utilized the MAP-MRI framework on a cohort of cognitively unimpaired participants.
- Analyzed MAP-MRI metrics, including NG and PA, in white and gray matter.
- Compared MAP-MRI results against DTI-derived metrics.
Main Results:
- Identified an opposing pattern in white matter: higher NG and lower PA in older adults, suggesting axonal degradation.
- Observed consistent NG and PA in gray matter with regional heterogeneity, possibly indicating reduced neuronal projections and increased glial concentration.
- Reported regional variations in age-related microstructural differences aligning with the posterior-anterior shift in aging paradigm.
Conclusions:
- MAP-MRI provides novel insights into age-related brain microstructure changes.
- Findings suggest distinct white and gray matter aging mechanisms.
- These results warrant further research into neurodegeneration and cognitive impairments.
