Transcranial Near-infrared Light Therapy for Mild-Moderate Alzheimer's Disease (NIR4AD)

Inclusion Criteria:

1. 50 - 90 years old, no gender limitation;

2. Meeting clinical diagnostic criteria of probable AD according to National Instituteon Aging and the Alzheimer's Association (NIA-AA) guidelines;

3. Clinical Dementia Rating Scale Total Score (CDR-GS) score ≥ 1 and ≤ 2, ClinicalDementia Rating Scale Memory Box score ≥ 0.5;

4. Amyloid PET or cerebrospinal fluid examination or blood biomarkers conforms tochanges in AD biomarkers;

5. The MMSE score is ≥ 12 and ≤ 26;

6. Education level is non illiterate or has received cultural education for 4-6 yearsor more;

7. If taking mental or cognitive improvement drugs, the dosage must be stable for atleast 3 months before the study, and remain unchanged during the light regulationintervention period. Unless otherwise specified, participants must consistently useall other (i.e. non Alzheimer's disease related) permitted concomitant medicationsfor at least 4 weeks before baseline;

8. Having a designated guardian or caregiver who can assist them in participating inthe experiment (defined as someone who can support participants throughout theentire study period and spend at least 8 hours with them per week);

9. Subjects with informed consent;

Exclusion Criteria:

1. Any neurological and psychiatric symptoms beyond the scope of symptoms that can becaused by Alzheimer's disease;

2. A history of transient ischemic attack (TIA), stroke, or epilepsy within 12 months;

3. Any mental diagnosis or symptoms that may interfere with the participant's researchprocess (such as hallucinations, severe depression, or delusions);

4. Contraindications to MRI, including pacemakers/defibrillators, ferromagnetic metalimplants, etc;

5. MRI shows other clinically significant lesions, which may indicate the diagnosis ofdementia beyond Alzheimer's disease;

6. MRI shows other important pathological findings, including but not limited to: 4 ormore microbleeds with a diameter of 10 millimeters or less; Single bleeding lesionwith a maximum diameter greater than 10 millimeters; Surface iron deposition area;Evidence of exudative edema; Evidence of brain contusion, encephalomalacia,aneurysm, vascular malformation, or infectious disease; Multiple lacunar infarcts orstrokes involving major vascular areas, severe small vessel or white matter lesions;Space occupying lesions; Or brain tumors (diagnosed as meningiomas or arachnoidcysts, lesions with a maximum diameter of less than 1 cm may not be ruled out);

7. A photosensitive response to sunlight or visible light, with eczema or increasedsensitivity on the skin at the intervention site;

8. Severe visual or hearing impairment;

9. Individuals who are addicted to alcohol, drugs, or other drugs or have a tendency tobecome addicted;

10. Participating in other AD clinical trials;

11. Any other medical conditions that are not stable and adequately controlled (such asheart, respiratory, gastrointestinal, kidney diseases), or situations that theresearcher believes may affect the safety of participants or interfere with theevaluation of the study;

12. Other conditions that, in the opinion of the investigator, may not be suitable forthis study.