Light Exposure as a Nonpharmacological Intervention for Alzheimer’s Disease

Abstract

AbstractBackgroundIn recent years, significant advances have been made in our understanding of the non‐visible biological impact of light (Vetter et al, 2021). Many of these advances can be traced to the 2002 discovery of a previously unknown retinal photoreceptor known as the intrinsically photosensitive retinal ganglion cell, or ipRGC, which is now known to be connected directly to our master circadian clock in our superchiasmatic nucleus (SCN). Now a growing body of clinical and applied research has shown how light spectrum, intensity, and timing can be used to promote circadian entrainment, leading to significant improvements in human health outcomes, including for people with Alzheimer’s disease and related dementia (ADRD).MethodMany of these clinical studies have used lighting interventions in elder care facilities to evaluate the impact of lighting as a nonpharmacological intervention to improve mood, anxiety, sleep quality, falls and other health metrics for ADRD populations. These studies typically gather light exposure and health metric information during control periods or with control populations using traditional lighting approaches and compare results to periods or populations under “circadian‐enhanced” lighting conditions, which generally means brighter and bluer lighting during the day and dimmer and redder light in the evening and night hours.ResultThe results from these studies have consistently demonstrated significant improvements in circadian entrainment, sleep quality, mood, anxiety, falls and other health metrics for ADRD populations under circadian‐enhanced lighting conditions.ConclusionThis talk will provide an overview of our current understanding of how light exposure impacts human physiology. We will discuss several completed and ongoing clinical studies conducted with ADRD populations, including several studies on which the speaker has been the Principal Investigator. We will cover what questions remain in this area and what studies can be developed in the future to address them. Finally, we will close with a discussion of tools, products, building designs and daily routines that can be applied today by clinicians and caregivers that are most likely to improve the health and wellbeing of ADRD patients based on what is known today about the impact of light exposure.