New research is helping to elucidate the relationship between the brain and the immune system in people experiencing prolonged anxiety after stress. The findings suggest that an excess of white blood cells in the spleen may be sending behavior-altering messages to brain for a long period of time after mice experience stress.
“We found that immune cells in the spleen can contribute to chronic anxiety following psychological stress,” said lead study author Daniel McKim, a graduate student at Ohio State University. “Our findings emphasize the possibility that the immune system represents a novel therapeutic target for the treatment of mental health conditions.”
McKim and his colleagues are focused on explaining the role between immunity and stress in mice who have faced “repeated social defeat,” in an effort to one-day improve the lives of people who suffer the effects of chronic psychological stress. The research was recently presented at Neuroscience 2016, the annual meeting of the Society for Neuroscience.
“Stress appears to prompt the release of stem cells from the bone marrow to the spleen, where they develop into white blood cells, or monocytes, and expand over time,” said co-author Jonathan Godbout. “Then the spleen becomes a reservoir of inflammatory cells.”
The researchers found that immune cell changes were consistent for nearly a month after the mice had experienced stress. They said that the spleen has been recognized as an important player in the sensitization that occurs in mice who have experienced prolonged stress, leading to both anxiety and cognitive problems later on in life.
Previous work conducted by the lab at Ohio State University, has shown that mice exposed to chronic stress face an increased risk of long-term anxiety and depression. This mouse model has been compared to the same symptoms seen in people with post-traumatic stress disorder.
“Maybe anxiety is a good thing for survival – it’s beneficial evolutionarily – but the issue becomes what happens when that system is put into overdrive,” said Godbout. “That’s when it gets problematic.”