Temple published an early study testing whether its wearable can track changes in blood flow to the brain. The study included 23 healthy adults and compared Temple’s Brain Flow metric with transcranial Doppler ultrasound, an established method for tracking blood-flow velocity in major brain arteries.

Brain Flow tracked changes seen with ultrasound

Participants cycled and repeatedly moved between standing and lying down. Temple’s Brain Flow score was compared with ultrasound measurements from the middle cerebral artery, one of the main vessels supplying the brain.

The two measurements moved together fairly closely. The correlation was 0.795 during exercise and 0.799 during the posture test.

The study also included a posture test to isolate blood flow. When participants lay down, their heart rate fell while blood-flow velocity in the brain increased. Temple’s Brain Flow score increased at the same time. In other words, the score appears to respond to changes in cerebral circulation that cannot be explained by heart rate moving in the same direction.

The findings come with some limitations. The study tested whether Brain Flow follows relative changes. It did not test if Temple can measure brain blood flow in absolute terms. It also cannot yet show how much of the optical signal comes specifically from circulation inside the brain. Furthermore, Temple funded the study, so this is company-funded validation which has not yet been peer-reviewed.

Temple is adding more science before launch

The paper arrives as Temple builds out its research team. In August, it acquired London longevity practice Longevous, with founders Robert Mohr joining as Chief Medical Officer and Avi Roy as Head of Science. Both had already been working with Temple on validation before the acquisition.

Temple’s wider platform is increasingly centred on Entropy, its proprietary score for estimating the body’s energy use in real time. That metric is currently based on just company-reported results, while Brain Flow is now measured in a public preprint. Temple says pre-orders for its launch device will open soon, with shipping planned before the end of 2026.