Color Dependence of OLED Phototherapy for Cognitive Function and Beta-Amyloid Reduction through ADAM17 and BACE1.

Previous studies have reported that 40 Hz visual stimulation (acute white light exposure) reduced Aβ levels in Alzheimer's disease (AD) mouse model. However, whether different light colors distinctly regulate AD pathologies has not been well characterized. In the present study, an optimized organic light-emitting diode (OLED)-based visual stimulation platform was developed to provide uniform illumination without blind spots, and the color-dependent effects on cognitive function and amyloid-β (Aβ) pathology were investigated in 5xFAD mice, an Aβ-overexpressing AD model. Acute exposure to white or red OLED light (1 h/day for 2 days) significantly improved cognitive function, reduced hippocampal Aβ plaque accumulation via increasing ADAM17 activity, and downregulated proinflammatory cytokine IL-1β levels in 3-month-old 5xFAD mice, whereas green or blue OLED light did not produce these effects. In addition, chronic white and red OLED stimulation (1 h/day for 2 weeks) was shown to enhance recognition memory; however, only red light further diminished Aβ plaque deposition by upregulating ADAM17 activity and suppressing BACE-1 activity without altering neuroinflammation in 6-month-old 5xFAD mice. Moreover, acute white and red OLED exposure (1 h, single session) was observed to enhance c-fos expression, which is associated with neural activation along the visual pathway, thereby suggesting a mechanistic link between light stimulation and cognitive enhancement. Taken together, these findings demonstrate that color-dependent visual stimulation may serve as a promising electroceutical strategy for AD, with red light uniquely combining memory enhancement, Aβ reduction via ADAM17 upregulation and BACE1 suppression, and anti-inflammatory effects.