Lights for aging: Can photobiomodulation restore functionality in the cerebral networks of aged individuals?

Of all our organs, the brain is particularly prone to aging. The neurons become increasingly more dysfunctional with age, leading to less efficient patterns of functional connectivity, not only within, but also between the different large-scale resting-state networks. Further, the aged brain shows weaker, less efficient patterns of activation when undertaking a particular task, such as a motor movement or recalling a memory. Quite remarkably, however, compensatory mechanisms do develop, where other brain regions are recruited to help perform the tasks. There is, however, much variability across different individuals in the ability to recruit such compensatory processes, and this has been referred to as cognitive reserve or resilience. In addition to these neuronal dysfunctions, the aged brain suffers from widespread inflammation. In terms of options to slow the aging process, there is nothing specific on offer, except for some recommendations to live a healthier life (e.g., change in diet, more exercise, and cognitive training). In this narrative review, we explore the idea that the use of red and near infrared light, referred to often as photobiomodulation, can slow neuronal wear and tear, reduce inflammation, enhance the overall function of the cerebral networks, and improve the quality of life in aged individuals. We hypothesize that the application of these specific wavelengths of light has the potential to improve aged-induced cell dysfunction and death, leading to a restoration of more functional patterns of activity across the aged brain and reducing the risk of developing a neurological disorder such as stroke or neurodegenerative disease.