40 Hz light preserves synaptic plasticity and mitochondrial function in Alzheimer's disease model

Alzheimer's disease (AD) is the most prevalent type of dementia. Its causes are not fully understood, but it is now known that factors like mitochondrial dysfunction, oxidative stress, and compromised ion channels contribute to its onset and progression. Flickering light therapy has shown promise in AD treatment, though its mechanisms remain unclear. In this study, we used a rat model of streptozotocin (STZ)-induced AD to evaluate the effects of 40 Hz flickering light therapy. Rats received intracerebroventricular (ICV) STZ injections, and 7 days after, they were exposed to 40 Hz flickering light for 15 min daily over seven days. Cognitive and memory functions were assessed using Morris water maze, novel object recognition, and passive avoidance tests. STZ-induced AD rats exhibited cognitive decline, elevated reactive oxygen species, amyloid beta accumulation, decreased serotonin and dopamine levels, and impaired mitochondrial function. However, light therapy prevented these effects, preserving cognitive function and synaptic plasticity. Additionally, flickering light restored mitochondrial metabolites and normalized ATP-insensitive mitochondrial calcium-sensitive potassium (mitoBKCa) channel activity, which was otherwise downregulated in AD rats. Our findings suggest that 40 Hz flickering light therapy could be a promising treatment for neurodegenerative disorders like AD by preserving synaptic and mitochondrial function.