Sleep Spindles and Slow Oscillations as Potential Biomarkers and Therapeutic Targets in Mild-to-Moderate Alzheimer’s Disease

This review critically evaluates evidence on sleep spindles (SP), slow oscillations (SOs), and their coordination in mild-to-moderate Alzheimer’s disease (AD), focusing on their relationships with cognition, AD biomarkers, and their therapeutic potential. Longitudinal studies associate greater SP and/or SO activity with better cognition and favourable amyloid and tau profiles after clinical onset. Spindle and SO coupling may index network integrity. Preserved NREM sleep oscillations are associated with lower orexin concentrations and weaker adverse relationships between orexin and cognitive and neuropsychiatric outcomes. Closed-loop acoustic stimulation and slow-oscillatory transcranial direct-current stimulation can modify SO activity, spindle activity, and coupling, although cognitive and biomarker benefits remain uncertain. Spindle-SO activity, including their temporal coupling, are associated with cognition and AD biomarkers across the disease continuum. Closed-loop acoustic and electrical stimulation can modify these oscillations, but biomarker-characterized trials in MCI and AD are needed to determine whether treatment produces durable cognitive and biomarker benefits.