“In stress situations, the body readies itself for fight or flight, prepares itself for potential injuries, too,” lead researcher Dr. Astrid Friebe said in a statement. “What is certain is that microglial cells adapt to the new conditions, in a way. The more frequently they get triggered due to stress, the more they are inclined to remain in that mode. This is when microglial cells start to pose a danger to the brain.”
Friebe and her colleagues have based their findings off ongoing research in the field of psychoneuroimmunology — the impact of the immune system on the progression of mental disorders. Experts in the this field of medicine focus on neural connections that go from the brain to organs of the immune system and back to the brain. Immune cells, like microglial cells, make their way to the brain where they are responsible for removing damaged synapses.
When the body senses a threat, as it does under stress, microglial cells are activated and turn destructive by triggering inflammation and releasing messengers that damage nerve cells. Multiple sclerosis and Alzheimer’s disease patients tend to have areas of the brain affected by inflammation or neurodegeneration that are bordered by microglial cells. The same cluster of microglial cells has been discovered in schizophrenic patients and are linked to the degeneration of synaptic links between neurons.
“Originally, the brain and the immune system were considered two separate systems,” said Dr. Georg Juckel, medical director at the RUB’s LWL university clinic for psychiatry, psychotherapy, and preventive medicine. “It was assumed that the brain operates independently from the immune system and has hardly anything to do with it. This, however, is not true.”
A similar study conducted by researchers from the University of California, Berkeley also found that chronic stress can lead to changes in the brain that cause the development of a mental disorder. The research team focused on the reduction of neurons and generation of white matter that results from chronic stress. This increase of white matter, particularly in the hippocampus, disrupts the balance and timing of communication in the brain.
“We studied only one part of the brain, the hippocampus, but our findings could provide insight into how white matter is changing in conditions such as schizophrenia, autism, depression, suicide, ADHD and PTSD,” lead researcher Daniela Kaufner said in a statement.
Source: Juckel G, Friebe A, et al. Mental disorders through permanent stress. Rubin. 2014.