Loss of Brain Structural qMRI Signatures in Aging

The human brain undergoes significant changes during aging, affecting its macrostructure and microstructure features and impacting its functionality. These aging related changes are oftentimes linked to different neurodegenerative diseases. Previous studies using MRI and molecular analyses have proposed that aging in each individual brain leads to increased similarity between different brain regions, whereas on the population level, they show greater variability. We investigated these hypotheses using multi-parametric, microstructural, quantitative MRI (qMRI) approaches. Using seven qMRI parametric methods in data from young and older adults, we created unique microstructural signatures of 128 brain regions. Our results supported both hypotheses: First, that inter-regional microstructural similarity is stronger within older individuals; and second, that the variability in microstructural signatures across individuals is also greater in older than in younger adults. Our findings provide new insights into the brain's microstructural changes during aging and demonstrate the potential of using multi-parameter qMRI techniques in neuroscience research.