Stress can scramble your brain’s internal GPS, MRI study finds

A recent MRI study conducted by researchers at Ruhr University Bochum in Germany has found that cortisol, a stress hormone, can disrupt the brain's internal navigation system, known as grid cells. The study involved 40 healthy male participants who underwent a virtual navigation task while their brain activity was monitored with MRI scanners.

Half of the participants were given cortisol, while the other half received a placebo. The results showed that cortisol significantly impaired participants' ability to navigate, causing them to make more errors in determining their path back to the starting point. This effect was consistent regardless of whether permanent landmarks were available or the complexity of the route.

The disruption in navigation was particularly noticeable when participants navigated without any permanent landmarks, causing grid cell activity to become almost entirely absent. Researchers also observed increased activity in the caudate nucleus, suggesting that the brain may attempt to compensate for the loss of the primary spatial mapping system through alternative strategies.

This finding may have implications for understanding Alzheimer's disease, as the entorhinal cortex, where grid cells are located, is one of the first regions affected by the condition. Chronic stress is also a risk factor for dementia, and the study reveals a critical mechanism through which cortisol can destabilize this sensitive brain region.