A gateway to stress in the brain discovered

Stress leads to depression, especially if difficult events occur during childhood. A study involving three Quebec researchers has found a “door” between the blood system and the brain that plays a crucial role in the stress-depression equation. Their work could lead to drugs and a better diagnostic test for depression.

“There is more and more interest in the link between the immune system, which is stimulated by social stress, and the brain,” says Caroline Ménard, lead author of the study published yesterday in the journal Nature Neuroscience and neurobiologist at the Mount Sinai School of Medicine in New York – starting in February at Laval University. “We are trying to understand how the molecules of the immune system circulating in the blood enter the brain. We found a door in the blood-brain barrier that separates blood and brain. ”

The type of stress that leads to depression can be overwork at work. Stress during childhood (poverty, parental separation, violence) also increases the risk of depression in adulthood.

When this “door” between the blood system and the brain was open, a very important area of ​​the brain in depression and mood regulation was invaded by immune system molecules that are generated by stress. The neurons of this region, called nucleus accumbens septi , were affected by these molecules of the immune system. Researchers have demonstrated this in the mouse and also thanks to two brain banks in Texas and the Douglas Institute at McGill University in Montreal.

“With this discovery, we could use magnetic resonance imaging (MRI) to see people who have an open door. One could have a more accurate diagnosis of depression. Explains Caroline Ménard.

A preliminary step in limiting the number of people who would be screened by MRI would be to measure in the blood the presence of molecules from the brain, which also circulate through the “door” opened by stress.

The other avenue of research that Ms. Ménard wants to follow when she moves to Laval University is to study people who are more resistant to stress than others. “There resilient mice, in which the door into the blood-brain barrier does not open in the presence of stress, says M me Ménard. There may be genes or molecules that come into play. It could give targets to close doors and treat depression. ”

In numbers
1.9 TIMES

increased risk of depression in children whose parents separate before they are 7 years old

3.5 TIMES

increased risk of depression for children whose parents are separating and whose mother is recovering as a couple before they are 7 years old

3,4 TIMES

increased risk of depression in children born to single mothers

Source: American Journal of Psychiatry

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