Early and accurate diagnosis of dementia remains a major challenge. Standard approaches such as MRI and PET scans can provide valuable information about brain structure and function, but they are expensive, not always accessible, and often too expensive for repeated use. A team of researchers in the UK has now demonstrated that a compact, noninvasive technology—broadband near-infrared spectroscopy (bNIRS)—may offer a new way to detect brain changes linked to Alzheimer's disease, even in the early stages.
In this pilot study reported in the Journal of Biomedical Optics , scientists used bNIRS to monitor both blood oxygenation and brain metabolism in response to visual stimulation. Unlike conventional near-infrared spectroscopy, which typically tracks only oxygenated and deoxygenated hemoglobin, the broadband approach also measures the oxidation state of cytochrome c oxidase (oxCCO), a key mitochondrial enzyme involved in cellular energy production. Previous work has shown that oxCCO activity is reduced in Alzheimer's disease, making it a promising biomarker for early detection.
The researchers enrolled three small groups of older adults: healthy controls (five participants), individuals with mild cognitive impairment (seven participants), and individuals with early Alzheimer's dementia (seven participants). Using a simple checkerboard visual stimulus, the team recorded changes in blood oxygen levels and oxCCO activity from the visual cortex. They then compared these brain responses with standard cognitive test scores.
The analysis revealed that certain features of the brain signals—such as the amplitude and peak delay of the response—varied across groups. Importantly, when the researchers used statistical modeling to link brain responses to cognitive performance, the canonical correlation was strong (r = 0.902). But when oxCCO-related measures were excluded, the correlation dropped significantly (r = 0.687). This finding suggests that including oxCCO improves the ability of bNIRS to capture clinically relevant brain changes.
Although this pilot study was in a small cohort, the results highlight the potential of bNIRS as an accessible brain-monitoring tool. Because the system is portable and can be used in participants' homes, it may eventually support wider and more frequent testing, helping clinicians track disease progression or evaluate treatment responses.
"Our work is the first to noninvasively measure oxCCO during functional tasks in people with dementia, using a wearable system," the authors write. They suggest that with further development, bNIRS could become part of the diagnostic toolkit for dementia, offering a low-cost, noninvasive, and patient-friendly complement to existing imaging methods.
For details, see the original Gold Open Access article by D. Acharya et al., " Mapping functional hemodynamic and metabolic responses to dementia: a broadband spectroscopy pilot study ," J. Biomed. Opt. 30(S2), S23909 (2025), doi 10.1117/1.JBO.30.S2.S23909 .
