Sustained stress erodes memory, and the immune system plays a key role in the cognitive impairment, according to the findings of a new study by scientists at Ohio State University.
Their work, which appears in The Journal of Neuroscience, builds on previous research substantiating the connections between chronic stress and lasting anxiety.
The latest study could one day lead to treatment for repeated, long-term mental assault such as that sustained by bullying victims and “those who report to beastly bosses,” the experts say.
The work is the first of its kind to establish the relationship between short-term memory and prolonged stress.
“This is chronic stress. It’s not just the stress of giving a talk or meeting someone new,” said lead researcher Jonathan Godbout, associate professor of neuroscience at Ohio State.
In animal models, mice that were repeatedly exposed to a larger, aggressive intruder mouse had difficulty remembering the location of an escape hole in a maze they’d mastered prior to the period of sustained stress.
They also had measurable changes in their brains, including evidence of inflammation brought on by the immune system’s response to the outside pressure. This was associated with the presence of immune cells, called macrophages, in the brain of the stressed mice.
The research team was able to pin the short-term memory loss on the inflammation, and on the immune system.
According to Godbout, the impact on memory and confirmation that the brain inflammation is caused by the immune system are important new discoveries.
“It’s possible we could identify targets that we can treat pharmacologically or behaviourally,” he said.
The Ohio State researchers are seeking to uncover the secrets behind stress and cognitive and mood problems with a long-range goal of finding ways to help those who are anxious, depressed and suffer from lasting problems, including post-traumatic stress disorder.
Their latest research focused on the hippocampus, a hub of memory and emotional response.
The scientists found that the stressed mice had trouble with spatial memory that resolved within 28 days. They also found that the mice displayed social avoidance, which measures depressive-like behaviour that continued after four weeks of monitoring.
And they were able to measure deficits in the development of new neurons 10 days and 28 days after the prolonged stress ended.
When they gave the mice a chemical that inhibited inflammation, the memory loss and inflammatory macrophages disappeared, but neither the brain-cell problem nor the depressive symptoms went away.
That led them to conclude that the post-stress memory trouble is directly linked to inflammation and the immune system, rather than to other damage to the brain.
Godbout believes that type of information can pave the way for immune-based treatments. (Caribbean 360)
