Introduction
Dementia remains a global public health challenge characterized by progressive cognitive decline impacting millions worldwide. Early and accurate risk stratification is essential for timely intervention, personalized management, and planning. Among the continuum of cognitive decline, subjective cognitive decline (SCD) and mild cognitive impairment (MCI) represent earlier clinical stages where meaningful prevention or delay of progression to dementia is possible. However, traditional clinical assessments and standard MRI-based visual rating scales have limited sensitivity to predict which patients will progress to dementia. Recent advances in neuroimaging have introduced the concept of brain-predicted age difference (brain-PAD), which generates an estimated brain age from structural MRI data and compares it to chronological age. This metric has been associated with neurodegeneration and clinical outcomes but its incremental prognostic value across cognitive stages and in relation to established biomarkers remains underexplored.
