News in Short

• Deepinder Goyal’s Temple wearable has completed its first validation study.
• The study involved 23 healthy adults.
• Temple was compared with Transcranial Doppler, a medical-grade brain blood flow measurement device.
• The wearable captured changes in brain blood flow during exercise and posture changes.
• The study found a strong association between Temple-BF and TCD measurements.
• However, the study has not yet been peer-reviewed and does not prove that Temple directly measures brain blood flow.

Deepinder Goyal’s wearable health-tech startup Temple has shared early findings from its first validation study. The results suggest that the device may be able to track changes in brain blood flow, something conventional wrist-based wearables such as smartwatches cannot currently do.

The findings are interesting because Temple is designed to sit on the side of the head, around the temple region. The company is attempting to use this position to capture health signals that are difficult to measure from the wrist.

However, there is an important caveat. The study is still awaiting peer review, and the researchers have not concluded that Temple can directly and accurately measure brain blood flow.

Temple was tested against a medical-grade device

The validation study involved 23 healthy adults. Researchers compared Temple’s Brain Flow Index, known as Temple-BF, against measurements from Transcranial Doppler (TCD). TCD is a medical-grade system used to measure blood flow through the brain and is described in the study as the gold standard for assessing cerebrovascular function.

The participants were tested under two conditions.

One involved cycling followed by recovery. The other involved moving from a standing position to lying down.

These situations allowed researchers to observe whether Temple could detect changes in brain blood flow alongside the changes recorded by TCD.

Temple tracked changes during exercise

During the cycling exercise, Temple reportedly tracked heart rate well, recording a Mean Absolute Percentage Error of around 4 percent.

More importantly, researchers found a strong temporal association between the brain blood flow readings generated by Temple and the Middle Cerebral Artery Velocity (MCAv) measurements recorded by TCD. This meant that Temple was able to follow the same general trends seen by the medical-grade system.

The study also found that brain blood flow increased during cycling compared with baseline and recovery. Both Temple-BF and TCD measurements reflected those changes.

The posture test is particularly interesting

The second test produced another notable result.

When participants moved from standing to lying down, their heart rate decreased, while blood flow in the brain increased. Temple was able to capture both changes.

This distinction matters because it suggests that the wearable was not simply estimating brain blood flow based on heart rate alone. If it had done so, a falling heart rate could have incorrectly suggested falling brain blood flow.

Instead, Temple-BF showed a rise that broadly matched the TCD measurements.

That is one of the more interesting aspects of the early findings.

How is Temple different from a smartwatch?

A smartwatch can monitor several signals, including heart rate. But its position on the wrist limits what it can directly observe about the brain.

Goyal’s argument is that Temple’s placement near the temporal region could provide access to signals that are not available from a wrist-worn device.

The study’s results support that possibility. During the posture test, Temple detected the increase in brain blood flow even as heart rate fell.

However, this does not mean Temple has already replaced medical equipment.

The study does not prove Temple measures brain blood flow

This is where the findings need to be viewed carefully.

The researchers found a strong relationship between Temple-BF and TCD’s MCAv readings. But they explicitly noted that this does not conclusively establish that Temple is accurately measuring brain blood flow activity.

There is also another possibility that researchers need to investigate. Temple could be detecting signals from tissue around the temporal region rather than directly measuring cerebral blood flow.

The study therefore points to a promising correlation, rather than definitive proof of what the wearable is measuring.

Temple is not ready to replace TCD

The researchers also noted some limitations with the TCD comparison. In certain cases, the TCD recording quality dropped when the headframe holding its probe moved during testing.

A compact wearable attached directly to the side of the head could potentially avoid some of those practical issues. Still, Temple should not be considered a replacement for TCD at this stage.

The study needs peer review and further research with larger and more diverse groups before stronger conclusions can be drawn.

Why Temple’s results matter

The potential here is significant. If Temple can reliably monitor changes in brain blood flow outside a clinical setting, it could open up new possibilities for continuous health monitoring.

For now, though, the more accurate takeaway is simpler: Temple has shown that its brain-flow readings can track trends seen by a medical-grade TCD device in an early study.

That is an encouraging first step, but it is still a first step.