The stress hormone, cortisol, disrupts the brain’s internal navigation system by impairing the function of grid cells, according to a new study from researchers at Ruhr University Bochum in Germany.
Published online in PLOS Biology on 12 March, 2026, the imaging study involved 40 healthy men and provides direct evidence that acute stress can compromise spatial orientation and the neural mechanisms that support it.
“It is well known that stress influences human behaviour and thinking, but the precise ways in which cortisol disrupts the brain circuits responsible for navigation have remained largely unclear until now.”
A team led by Osman Akan from the Department of Cognitive Psychology at Ruhr University Bochum conducted the research with colleagues from the Department of Neuropsychology and scientists at University Hospital Hamburg-Eppendorf.
Participants completed a virtual orientation test while undergoing MRI scans. Each of the 40 men performed the task on two separate days. On one day they received 20 milligrams of cortisol, while on another day they received a placebo. Brain activity was recorded throughout both sessions.
In the virtual environment, participants moved through a large meadow landscape. They navigated toward trees that disappeared once reached and then had to return to their starting point without directional cues.
Two navigation conditions were tested: a landmark free environment where only temporary trees were present, and a landmark condition in which a lighthouse served as a stable reference point.
Participants performed significantly worse after receiving cortisol. Compared with placebo sessions, they made larger errors when attempting to locate destinations, regardless of path complexity or the presence of landmarks.
Functional MRI results showed that under normal conditions a group of neurons in the entorhinal cortex fired in a grid like pattern during navigation tasks. These neurons, known as grid cells, act as an internal coordinate system for spatial orientation.
Under cortisol exposure, these activity patterns became unclear. The disruption was strongest when no landmarks were available, where grid cells showed almost no organised function.
“Under stress, the brain loses the ability to effectively utilize its internal navigation maps,” explains Dr Akan.
The scans also revealed increased activation in the caudate nucleus when cortisol was present.
“This indicates that the brain is trying to compensate for the loss of the main navigation system in the entorhinal cortex through alternative strategies,” says Dr Akan.
The entorhinal cortex is one of the brain regions most vulnerable in early Alzheimer’s disease. Chronic stress is already recognised as a risk factor for dementia.
“Because chronic stress is a risk factor for dementia, our study reveals a critical mechanism for how stress hormones destabilize this sensitive region,” explains Dr Akan.
The findings suggest that stress may directly impair everyday spatial abilities such as navigating unfamiliar places. The researchers say future work will examine whether long-term elevations in cortisol produce similar disruptions and whether they contribute to age related cognitive decline.