Recruitment has been too slow. We are considering some changes to the protocol.

The active Neuro RX Gamma device uses non-invasive near-infrared energy delivered to the brain with the intention to improve cognitive functioning and quality of life in patients with moderate to severe Alzheimer's Disease. Treatment will occur at home-based treatment sessions with the device.

A potential participant will undergo pre-screening and screening assessments to assess eligibility for the study. Eligible participants will undergo a baseline visit in which they will be randomized to either active or sham Neuro RX Gamma device.

The Vielight Neuro RX Gamma is a non-invasive device that administers low-energy near-infrared LED (light emitting diode) light to the brain transcranially and intranasally.

There are two treatment phases in the trial, each with a duration of 12 weeks. The patient along with the caregiver will perform home (or living facility) - based treatments with the device and document the sessions in a patient diary. The device will be applied to the patient participant by a dedicated caregiver for a 20 minute daily session, 6 days a week for a total of 12 weeks. The study participant and caregiver will be required to return to the clinic for follow-up assessments at 12 and 24 weeks post randomization, between treatment phases.

228 patients will be enrolled across 12 sites in Canada and the United States.

Inclusion Criteria:

1. Diagnosis of AD, defined as probable Alzheimer's disease of the National Institute of Neurological and Communicative Disorders and Stroke and the Alzheimer's Disease and Related Disorders Association.
2. Mini-mental state examination (MMSE) score between 8-20.
3. If receiving AD/psychotropic medication, must be on a stable dosage for at least 12 weeks prior to trial enrolment with no anticipated changes for the duration of the trial
4. Age 50 and older at the time of enrolment.
5. Severe Impairment Battery score at baseline ≤90
6. Adequate caregiver to ensure compliance of home-based treatments and to complete study assessments and questionnaires.

Exclusion Criteria:

1. Evidence of a relevant abnormality other than Alzheimer's disease on MRI or CT scan obtained within previous 24 months of enrolment into the trial, as listed below:

   1. Detection of more than 2 subcortical lacunar infarcts
   2. Any hemorrhage or infarct in a strategic location, such as the anterior nuclei of the thalamus (including dorso-medial nucleus)
   3. Space-occupying lesions compressing or compromising brain structures. (Note small meningiomas not compressing brain areas may be allowed)
   4. Patients with imaging findings that in the opinion of the investigator could be contributing to cognitive impairment (such as major cortical strokes, extensive white matter disease, etc.)

   Any patient without a scan in the past 2 years should undergo an MRI or CT as part of the study's screening assessment.

2. History of significant agitation and/or aggression.

3. History of stroke or epileptic seizures.

4. Current neurologic disease affecting cognition other than Alzheimer's disease.

5. Photosensitivity reactions to sunlight or visible light (polymorphous light eruption, solar urticaria, persistent light reactivity).

6. History of recurrent epistaxis within the last 24 weeks or currently taking major anti-coagulants (including warfarin, low molecular weight heparin)

7. Increased skin sensitivity at the treatment site including active herpes simplex in the treatment area, history of keloid formation, or history of retinoid use in the past month.

8. Pregnant or lactating or planning to become pregnant.

9. Currently undergoing light therapy treatment.

10. Current participation in another interventional clinical trial.

11. Any reason that, in the opinion of the investigator, might place a participant at unacceptable risk for participation in the trial.

12. Subject and/or caregiver does not speak English at a level necessary for the completion of the assessments.