The ALZLIGHT STAGE III Study is a continuation of the ALZLIGHT Pilot - Study on Safety, Feasibility and Neural Activation of Non-Invasive Light Therapy System. As with the first two stages, this study will examine whether entrainment of 40 Hz neural oscillation by novel 40 Hz Invisible Spectral Flicker is a potential therapy for Alzheimer's Disease. In order to examine this, 62 patients with mild to moderate Alzheimer's Disease will be recruited. The patients will be exposed to the Non-Invasive Light Therapy System for 1 hour a day for 6 months. The effect will be measured by a combination of electroencephalography, cognitive testing, functional magnetic resonance imaging, magnetic resonance spectroscopy and actigraphy.

Recent studies in mouse models of Alzhimer's Disease (AD) have shown that exposure to 40 Hz stroboscopic light therapy for one hour a day, resulted in slowing disease progression and lead to multiple neuroprotective effects such as cognition and memory recovery, and even scavenged both tau and Aβ protein species. Hence, the 40 Hz stroboscopic light therapy has a considerable potential for treatment of humans.

This study will utilize a novel way of masked light by alternating the spectral composition of a white light, rendering the flicker invisible to the conscience perception, while still entraining 40 Hz oscillations in the brain.

In the study, 62 patients with probable mild to moderate AD will be exposed to either invisible spectral flickering light through the Light Therapy System (LTS) (active setting) or continuous non-flickering white light (sham setting) for 1 hour each day. The sham setting is a high quality sham intervention as subjects will be blinded to the setting, both appear as white light.

The study participation will last 12 months for each participant and consist of 3 periods: An enrollment period, a randomized intervention period of 6 months, and 6 months of active intervention.

In order to test whether the LTS intervention is a potential treatment for AD, cognition will be measured by neuropsychological tests at baseline and at follow-ups. To get a better understanding of the potential effects, markers of efficacy based on MRI, MRS, EEG and blood samples will be tested.

The results from this study will increase the understanding of the impact of gamma oscillations in the human brain, and how it can be utilized as a novel and important tool for the treatment of neurodegenerative diseases.

Inclusion Criteria:

• Adult competent person, able to understand the nature of the study and give written informed consent.
• Diagnosed with probable mild to moderate AD based on NIA-AA diagnostic criteria or in a prodromal stage of AD with at least one positive biomarker of AD.
• Age > 40 years. Females must be post-menopausal.
• Fluent in Danish.
• > 8 years of normal school education
• Pass a color-blindness test (Ishihara color test)
• Have visual and auditory capabilities, and language skills necessary for neuropsychological testing.
• Participants must have a designated caregiver, who is available to the participant and can provide the necessary assistance with using the LTS device and the Actigraph wearable at home and assist with clinical visits and other practical issues

Exclusion Criteria:

• Profound visual impairment (visual acuity > 0.5) provided correction with spectacles, if needed
• Significant abnormalities related to important parts of the brain, e.g., the visual system, prefrontal cortex, or hippocampus, or relevant lesions detected by pre-trial imaging.
• Prior history of significant diseases related to the visual system or the brain.
• Medication: Use of any antiepileptic drugs, neuromodulating drugs or high dose of sedatives will be excluded.
• Prior history of substance abuse within the past 2 years.
• Any significant systemic illness or unstable medical condition, which could lead to difficulty complying with the protocol (at the discretion of the PI)

Double-blinded