Brain age (MRI-based)

MRI-based brain age is a biological-age estimate derived from structural or functional brain imaging features—including cortical thickness, white-matter integrity, grey-matter volume and functional connectivity—processed by machine-learning models trained on large neuroimaging cohorts. The gap between predicted brain age and chronological age, termed the brain-age gap or BrainAGE (introduced by Franke et al., 2010), is a biomarker of brain health: a positive gap (brain appearing older) associates with cognitive decline, neurodegeneration, stroke and all-cause mortality, while a negative gap is linked to better cognitive reserve. Accuracy and interpretability vary with imaging protocol, preprocessing pipeline and training cohort demographics.