Severe infection can cause lasting mood disorders. Sepsis is linked to a higher risk of anxiety, PTSD and other mental health problems. A new study points to a cause. Two brain circuits drive anxiety after infection: the bed nucleus of the stria terminalis and the central amygdala.
Summary: Most people do not link mental health problems with infections. But studies show the brain controls infection and swelling (inflammation) in many ways. These include hormone responses and even changes in behavior. Studies also show that severe illness like sepsis brings a higher risk of anxiety, PTSD, and other mental health problems. Until now, researchers did not know why. The new study points to certain brain circuits. When the bed nucleus of the stria terminalis and the central nucleus of the amygdala switch on, they play a key role in anxiety and PTSD after infection.
Most people do not link infections with mental health problems. But the new study shows that some severe infections may change how certain brain centers work. This can lead to different mood disorders. It would be foolish to think that infection or inflammation in the body cannot touch mental health. The brain has a say in everything the body does. It also controls the immune response.
Sometimes, severe infections can throw brain function off in many ways. Science is just starting to learn how the brain controls inflammation, both in one spot and across the whole body. The brain seems to sense and control inflammation in two ways. The first is the blood (humoral) pathway. Some inflammatory chemicals in the blood can enter the brain. So the brain can sense inflammation and how bad it is, and respond to match.
The second way is the nerve pathway. Sensory nerves send signals to the brain, including news about inflammation in one area. Then the brain can take control. Take the vagus nerve. It can sense even the tiniest inflammation in the gut and lungs. Once the brain gets signals from the blood and nerves, it starts its control responses. These involve hormones, automatic body functions, and behavior. Among the nerve pathways, the autonomic nervous system and the limbic system play key roles in these responses.
One hormone response is the release of cortisol, a stress hormone. Cortisol is quite good at controlling inflammation. Changes in behavior also help control inflammation. So shifts in mood, appetite, and sleep all play a key role in controlling inflammation.
All these changes in behavior aim to control inflammation. But sometimes the body may fail to respond the right way. This can cause mood dysregulation and raise the risk of mental disorders. Sepsis is one condition where the body often fails to respond well. It is a severe infection that spreads through the body. It causes a huge immune response and inflammation. Sepsis is one of the top causes of death in the world, because it is very hard to control with antibiotics.
Sepsis is life-threatening, so the brain’s response to it is also massive. Studies now suggest that this response may badly damage mental health. It can lead to chronic anxiety, depression, and other mental health problems. PTSD is another common result of a severe, long infection like sepsis.
Doctors know that sepsis raises the risk of anxiety, PTSD, depression, and other mental health problems. But they do not know how to lower this risk, because little is known about how it happens.
In one of the first studies of its kind, published in the journal Brain, researchers looked at how infection and inflammation might cause mental health problems. In the lab, they gave mice sepsis. After two weeks, these mice developed anxiety. They also showed signs that look like PTSD.
The study found changes in certain brain circuits, like the bed nucleus of the stria terminalis. More important, it found changes in the central nucleus of the amygdala. This study is one of the first to find changes in brain circuits tied to anxiety and PTSD after sepsis. These findings can guide future studies.
Learning how sepsis or severe inflammation harms mental health and causes depressive mood disorders may help find ways to prevent them and better treatment. These findings matter even more because brain inflammation and the mental disorders it causes also show up in people hit by Covid-19.
Frequently asked questions
Can sepsis cause anxiety?
Yes. Sepsis is a severe infection that spreads through the body. It is linked to a higher risk of anxiety, PTSD, depression, and other mental health problems. Because sepsis is life-threatening, the brain’s response to it is massive. Studies now suggest this response can damage mental health and lead to chronic anxiety.
What does sepsis do to you mentally?
Sepsis can leave lasting changes in mood. Survivors face a higher risk of chronic anxiety and depression. PTSD is another common result of a severe, long infection like sepsis. Doctors know about this risk. But they do not yet know how to lower it, because little is known about what links the infection to these mental health problems.
How can a severe infection affect your mood?
The brain senses and controls inflammation in two ways. Inflammatory chemicals in the blood reach the brain. Nerves such as the vagus nerve report inflammation in organs like the gut and lungs. The brain answers with the stress hormone cortisol. It also changes mood, appetite, and sleep. When those responses fall short, mood can get thrown off and the risk of mental disorders rises.
Which part of the brain is linked to anxiety after sepsis?
In a study published in the journal Brain, researchers gave mice sepsis. Two weeks later the mice showed anxiety and signs that look like PTSD. The researchers found changes in the bed nucleus of the stria terminalis. More important, they found changes in the central nucleus of the amygdala. It is one of the first studies to tie these brain circuits to anxiety and PTSD after sepsis.
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Sources
- Bourhy L, Mazeraud A, Costa LHA, et al. Silencing of amygdala circuits during sepsis prevents the development of anxiety-related behaviours. Brain. 2022;145(4):1391-1409. PMID 35441215 · DOI 10.1093/brain/awab475.