Re-tuning the brain: The promise of 40 Hz sensory stimulation in Alzheimer's disease.

Growing interest in noninvasive neuromodulation posits 40 Hz sensory stimulation as a potential intervention for Alzheimer's disease. Early studies suggested that 40 Hz visual flicker entrains gamma activity and reduces amyloid pathology; however, later work found either absent entrainment or even increased amyloid burden, revealing strong dependence on disease stage, network integrity, and stimulation parameters. Initial clinical investigations suggest that 40 Hz stimulation is safe, well-tolerated, and capable of modulating cortical network dynamics and improving cognition, despite limited effects on amyloid burden. These findings suggest a shift from molecular pathology to network plasticity as the primary target of gamma stimulation.