[Role of "light therapy" among older adults with dementia: an overview and future perspectives]

Given the relatively modest therapeutic benefits of drug treatments (and their associated costs) in dementia, there is a growing interest in non pharmacological approaches, including light therapy (light based therapy, LBT). Although various literature reviews exist, little attention has been given to the effects of these therapies (according to their modalities of application) on parameters related to both circadian rhythm and clinical parameters associated with dementia.

To provide an overview of available studies using LBT as non-pharmacological approach for managing persons with dementia and to make recommendations for its use.

Systematic searches in Medline and PsycINFO were carried out, from their inception to February 2017, by means of the combination of key words including dementia and light therapy.

Forty-two articles were reviewed with particular attention to the subjects' characteristics and the modalities of the therapy. The effect of LBT has been considered as a mean of intervention to entrain the circadian rhythm as well as in a clinical approach to reduce behavioral disorders, to reduce cognitive decline or loss of independence, and so on. Depending on the parameters and modalities, the effect of LBT is partially or non-significant.

Based on this literature review, some recommendations were formulated: prioritizing 'naturalistic' devices, setting a minimum threshold of 2,000 lux light intensity peak, testing the modulation of the light intensity during the day and finally, assessing the adequacy between the type of light (color) and the desired therapeutic objective (relaxing or stimulating effect).