New studies are suggesting a link between the immune system and the way the body reacts to stress. Research with rodents are raising hopes that one day, tweaking a person's immune system could be a way to treat or even prevent conditions like PTSD, Nature reports.
“I think there’s kind of a frenzy about inflammation in psychiatry right now,” says Christopher Lowry from the University of Colorado-Boulder. Lowry and colleagues found a connection between the immune system and stress in mice when they injected the rodents with a common bacterium called Mycobacterium vaccae once a week for three weeks to modulate their immune systems. These mice were tested against a group of untreated mice by putting both in cages with larger animals. The untreated mice were more timid, and later on they developed stress-based reactions, such as an inflamed colon. Meanwhile, rodents who got the immune system-boosting injection dealt with their aggressors more confidently and looked healthier afterward. They were more proactive; the others simply surrendered.
Lowry's team conducted a second experiment that reached a similar conclusion. In this one, they treated rats with the same kind of bacterium and also kept a control group of rats with untreated immune systems. Lowry and colleagues trained both groups to associate a particular sound with an electrical shock to the foot. Then, once the rats knew to fear the sound, the researchers began to play the sound without the pain. The treated rats learned not to be afraid much faster than the untreated rats did.
These findings were presented at a meeting of the International Behavioral Neuroscience Society earlier this month. And they seem to back up what many scientists already suspected -- and what early studies have already shown -- about a connection between the state of the immune system and mental conditions, such as depression and PTSD. The connection also appeared in studies involving members of the military, who are at a high risk for PTSD. Those studies found that soldiers with higher levels of a particular inflammatory protein are at a higher risk of developing the disorder.
The big question now is whether the connections seen in these new rodent studies also appear in humans, and whether that opens new avenues for treating mental health via the immune system. We may soon find out: University of Manchester's Bill Deakin is about to test whether treating schizophrenia patients with a drug that fights brain inflammation can help to slow the development of the disease.