In 1924, the study of brain disease took a giant leap forward when Hans Berger recorded the first human electroencephalograms (EEG).

We are now on the cusp of another innovation with “the potential to revolutionize how we study and care for the brain.” That’s according to the authors of a new review on the state of wearable technology that integrates EEG with blood flow imaging, using functional near-infrared spectroscopy (fNIRS).

The latter is similar to positron emission tomography (PET) and functional magnetic resonance imaging (fMRI) — which are also sometimes paired with EEG — in its non-invasive ability to measure hemodynamic activity in the brain. The advantage it has over these other imaging techniques is that fNIRS is inexpensive, lightweight, and portable.

The combination of EEG and fNIRS (EEG-fNIRS) has already demonstrated its utility in a number of clinical areas including stroke, Parkinson disease, epilepsy, and the care of neonates.

A new study of Alzheimer’s disease, published in the journal Biomedicines, has found considerable added value for early detection by combining these technologies.

In this study, EEG-fNIRS was used to measure neurovascular coupling, which quantifies the relationship between local electrical activity in the brain and resulting increases in blood flow. The study included 35 participants, 18 controls and 17 patients with Alzheimer’s disease. Neurovascular coupling was found to be significantly lower in the Alzheimer’s group.

This phenomenon has been linked previously to early detection of Alzheimer’s previously using EEG combined with fMRI. Using fNIRS as well, which is much less expensive and more portable than fMRI, opens up this diagnostic tool to far more people.

While the value of this type of multimodal brain analysis has been increasing over the years, the technology has been lagging. Often EEG-fNIRS is implemented using cobbled together off-the-shelf units. This poses a number of issues, including spacing all the electrodes and sensors on one scalp (especially in neonates), signal interference, and synchronizing recordings.

Since 2013, various researchers and manufacturers have collaborated to try and solve these issues by integrating the two systems into a single wearable unit.

While there continue to be glitches (outlined well in the review mentioned previously), these units have improved considerably. With the integration of microchip technology, according to the review authors, we are now in sight of perfecting the technology and exponentially expanding its use.

“With multidisciplinary efforts from engineers, medical physicists, and clinicians, this ‘ideal’ technology could become possible in the next few years, and it would potentially have wide-reaching implications for sectors including neuroscience, psychology, clinical neurology, BCI, neurorehabilitation, and personalized healthcare,” they write.