Stress hormone cortisol disrupts brain's navigation cells, study shows

In an experiment at Ruhr University Bochum, 40 male volunteers completed a spatial orientation task inside an MRI scanner on two separate days, receiving either 20 mg of cortisol or a placebo each time. Cortisol exposure caused participants to make significantly larger errors when finding their way back to a starting point, regardless of route complexity or the presence of a lighthouse landmark. Functional imaging revealed that the normally precise grid-cell activity in the entorhinal cortex became markedly less distinct, especially in landmark-free conditions where it nearly vanished.

Simultaneously, the caudate nucleus showed heightened activation, indicating the brain may switch to an alternative navigation system when the primary map is compromised. The authors note that because the entorhinal cortex is an early site of Alzheimer’s pathology, stress-induced disruption could have implications for dementia risk. Findings appear in the journal PLOS Biology.