Shedding Light on Dementia With Lewy Bodies: a Multimodal 'Bright Light Treatment' to Modulate Brain Functions

The study presents three specific aims: 1) explore the potential alterations of mRCG cells in a population of DLB patients; 2) explore the efficacy of a multimodal intervention combining blue-enriched Bright Light Therapy (BLT) with Cognitive Behavioral Therapy (CBT); 3) explore changes in mRGCs system after BLT using a monochromatic light fMRI protocol. The study enrolled 40 patients with DLB, diagnosed according to established criteria and 40 age-matched controls. All participants underwent neurological, neuro-ophthalmological and neuropsychological assessments. This proposal is based on three main hypotheses: 1. mRGC alterations in DLB: Patients with DLB are expected to show alterations of the melanopsin retinal ganglion cell (mRGC) system, similar to those reported in Alzheimer's disease and Parkinson's disease. Given the role of mRGCs in circadian and visual functions, these alterations may contribute to circadian and visuospatial disturbances in DLB. The mRGC system were evaluated using pupillometry to assess mRGC-mediated pupillary responses in DLB and healthy controls. Associations between mRGC alterations and clinical features of DLB were also be investigated. 2. Effects of multimodal treatment: A multimodal intervention combining blue-enriched Bright Light Therapy (BLT) with Cognitive Behavioral Therapy (CBT) is hypothesized to be more effective than CBT alone in improving cognitive performance in DLB. Participants were randomly and blindly assigned to the experimental or active control group. Both groups received 15 one-hour sessions, three times per week for 5 weeks. Neuropsychological outcomes were assessed in both groups. 3. mRGC-mediated brain responses: Monochromatic light stimulation during fMRI may provide a functional measure of mRGC-mediated brain responses and help characterize changes in the mRGC system following multimodal BLT plus CBT treatment. A longitudinal monochromatic fMRI protocol was performed at baseline and within 3 weeks after the final treatment session to investigate changes in mRGC-mediated brain functional responses following treatment in DLB.