Encephalitis Clinical Trials

The goal of this pilot 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 older adults. The main questions it aims to answer are: * Does tPBM enhance neurovascular coupling responses during memory and finger tapping tasks? * Are these improvements linked to better cognitive performance 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 either active tPBM or sham stimulation sessions for 4 weeks, every other day using a portable intervention device. * 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), transcranial doppler (TCD) flowmetry. * Retinal vessel reactivity will be measured during flickering light stimulus using a special camera (dynamic vessel analysis, DVA). * Provide blood samples to test for biomarkers of inflammation, oxidative stress and brain cell damage.