In this pilot study, published in the Journal of Biomedical Optics, scientists employed bNIRS to measure blood oxygenation and brain metabolism in response to visual stimulation.
A noninvasive neuromonitoring technology uses broadband near-infrared spectroscopy to measure concentrations of oxidized cytochrome c oxidase (oxCCO), a metabolic mitochondrial enzyme linked to Alzheimer’s disease. A pilot study suggests this may be an effective portable technique for diagnosing and monitoring dementia. Image courtesy of D. Acharya et al. Image Credit: University of Cambridge
Early and reliable diagnosis of dementia remains a significant difficulty. Standard techniques, such as MRI and PET scans, can give helpful information about brain anatomy and function, but they are costly, not always accessible, and sometimes too costly for repeated usage.
A team of researchers in the United Kingdom has recently proved that a small, noninvasive tool called broadband near-infrared spectroscopy (bNIRS) could offer a novel approach to identifying brain alterations associated with Alzheimer's disease, even in its early stages.
Unlike conventional near-infrared spectroscopy, which normally tracks oxygenated and deoxygenated hemoglobin, the broadband technique also assesses the oxidation status of cytochrome c oxidase (oxCCO), a critical mitochondrial enzyme involved in cellular energy generation. Previous research indicates that oxCCO activity is decreased in Alzheimer's disease, making it a possible biomarker for early identification.
The study included three small groups of older adults: healthy controls (five), those with moderate cognitive impairment (seven), and those with early Alzheimer's disease (seven). The scientists measured blood oxygen levels and oxCCO activity in the visual cortex using a simple checkerboard visual stimulus. They then compared the brain responses to typical cognitive test results.
The study discovered that specific aspects of brain signals, such as response amplitude and peak delay, differed between groups. Importantly, when the researchers employed statistical modeling to relate brain responses to cognitive function, the canonical correlation was high (r = 0.902).
However, when oxCCO-related indicators were eliminated, the association decreased dramatically (r = 0.687). This data shows that incorporating oxCCO increases bNIRS’ capacity to detect clinically important brain changes.
Although this pilot study had a modest sample size, the findings demonstrate bNIRS's promise as an accessible brain-monitoring technique. Since the device is portable and can be used in participants' homes, it can possibly allow for more extensive and frequent testing, assisting doctors in tracking disease progression or assessing treatment responses.
“Our work is the first to noninvasively measure oxCCO during functional tasks in people with dementia, using a wearable system,” stated the authors.
They believe that with additional research, bNIRS might become a valuable diagnostic tool for dementia, providing a low-cost, noninvasive, and patient-friendly alternative to present imaging approaches.
Journal Reference:
Acharya, D., et al. (2025) Mapping functional hemodynamic and metabolic responses to dementia: a broadband spectroscopy pilot study. Journal of Biomedical Optics. doi.org/10.1117/1.JBO.30.S2.S23910.