Repeated stress may cause cognitive impairment

Subjecting the brain’s prefrontal cortex (PFC) to repeated stress significantly impairs the temporal order recognition memory by suppressing glutamate receptor expression and function, according to a recently published study.

Eunice Y. Yuen, PhD, and colleagues at the department of physiology and biophysics, State University of New York at Buffalo, conducted their research on juvenile male rats. Their results, which also provided insight into why stress responses can trigger neuropsychiatric disorders, are published in the journal Neuron.

Stress hormones target the prefrontal cortex (PFC), a region of the brain that controls “high-level ‘executive’ functions, including working memory, inhibition of distraction, novelty seeking and decision making,” the researchers wrote. Yuen and colleagues sought to learn more about the physiological consequences and molecular targets of long-term stress in PFC, “especially during the adolescent period when the brain is more sensitive to stressors.”

The researchers determined that under repeated stress the lab animals experienced a reduction in glutamate receptors, resulting in a “detrimental effect on PFC-dependent cognitive processes.” Glutamate signaling plays a critical role in PFC function. They further identified molecular mechanisms that linked stress with a decrease in glutamate receptors. By inhibiting these mechanisms, Yuen and colleagues prevented the stress-induced decrease in glutamate receptors and recognition memory.

The researchers found, as a result of repeated stress, a link between a loss of glutamate receptors and PFC cognitive processes.

“Since PFC dysfunction has been implicated in various stress-related mental disorders, delineating molecular mechanisms by which stress affects PFC functions should be critical for understanding the role of stress in influencing the disease process,” they wrote.