Dual decline in cognition and gait speed is associated with lower myelin content across age

Motivation: Dual declines in cognition and gait speed are associated with increased dementia risk, yet their link to brain microstructural changes, especially myelination, is not fully understood. Goal(s): This study investigates the association between decline types and white matter myelination, a critical cerebral tissue determinant. Approach: Using advanced MRI, we performed linear regression analyses to assess the relationship between myelin content and decline type classified by rates of cognitive and gait speed decline. Results: Dual-decliners exhibited the lowest levels of myelin content, while non-decliners showed higher myelination across age. Impact: This research reveals distinct myelin content levels by decline type, suggesting that tracking cognitive and gait decline may cost-effectively monitor brain health. It highlights myelination's role in brain aging, where its degeneration may drive both declines and increased dementia risk.