A new study reveals that after a stroke, the undamaged side of the brain can appear biologically younger as it compensates for lost function. Researchers analyzed MRI scans from over 500 stroke survivors worldwide using AI models. The findings suggest neuroplasticity helps explain persistent motor impairments.
Researchers from the USC Mark and Mary Stevens Neuroimaging and Informatics Institute analyzed brain scans from more than 500 stroke survivors across 34 centers in eight countries. The study, part of the ENIGMA Stroke Recovery Working Group and published in The Lancet Digital Health, used deep learning to estimate the biological age of 18 brain regions via MRI data. They measured brain-predicted age difference (brain-PAD) against participants' actual ages to assess brain health changes post-stroke. This approach revealed that larger strokes speed up aging in the damaged hemisphere while making the opposite, contralesional side appear younger, particularly in the frontoparietal network involved in movement planning and attention. Hosung Kim, associate professor of research neurology at the Keck School of Medicine of USC and co-senior author, stated, 'Larger strokes accelerate aging in the damaged hemisphere but paradoxically make the opposite side of the brain appear younger.' He added that this pattern reflects the brain reorganizing undamaged networks to compensate for impaired motor function, especially evident in survivors with severe movement issues after over six months of rehabilitation. Arthur W. Toga, director of the Stevens INI, noted, 'By pooling data from hundreds of stroke survivors worldwide and applying cutting-edge AI, we can detect subtle patterns of brain reorganization.' The work, funded by the National Institutes of Health, aims to inform personalized rehabilitation by tracking these changes over time.