The goal of this clinical trial is to test whether transcranial photobiomodulation (tPBM), a non-invasive brain stimulation technique using near-infrared light, can improve brain blood flow regulation (neurovascular coupling) and cognitive function in people with mild cognitive impairment (MCI). The main questions it aims to answer are:
* Does tPBM enhance cognitive function and cerebral hemodynamic responses during memory and finger tapping tasks?
* Does tPBM reduce oxidative stress, inflammation, and mitigate brain cell damage?
* Is cognitive improvement linked to amyloid status, greater cerebral hemodynamic response, and lower levels of brain inflammation and oxidative stress? Researchers will compare an active tPBM treatment arm to a sham treatment arm to see if tPBM leads to measurable improvements in brain activity and cognitive function compared to no active stimulation.
Participants will:
* Receive a 20-minute-long active tPBM or sham stimulation session once per day, 6 times per week, for 12 weeks.
* Complete questionnaires and an iPad-based cognitive testing protocol.
* Complete memory and motor tasks while their brain activity is measured using non-invasive techniques: simultaneous functional near-infrared spectroscopy (fNIRS) and electroencephalography (EEG). Dynamic analysis of the vessels in the eye will also be performed based on eligibility. Transcranial Doppler (TCD) flowmetry is optionally performed.
* Provide blood samples to test for biomarkers of inflammation, oxidative stress, and brain cell damage.