In this feature, we ask whether there are links between inflammation and anxiety. Although evidence is slowly mounting, we have a great deal to learn about the relationship between the two.
Anxiety is normal. Most people will feel anxious now and again. For people with an anxiety disorder, however, feeling anxious is more frequent, intense, and persistent.
For these individuals, anxiety is difficult to control and can interfere with their everyday lives.
There are a range of anxiety disorders. They include generalized anxiety disorder (GAD); social anxiety disorder, which is also called social phobia; separation anxiety disorder; and post-traumatic stress disorder (PTSD).
Some people experience more than one form of anxiety disorder at the same time.
Anxiety disorders are common. According to the World Health Organization (WHO), in 2015, an estimated 3.6% of the global population had an anxiety disorder, which is around 264 million people.
Scientists still do not know the precise causes of anxiety, but some likely factors include overactivity in certain parts of the brain, an imbalance of neurotransmitters, genetics, trauma, personality traits, chronic pain, and substance misuse.
Even before the pandemic, anxiety appeared to be increasing, particularly in the West. Understanding how and why anxiety disorders emerge is urgent. Some scientists are investigating the potential role of inflammation.
In brief, inflammation is a natural and beneficial reaction to harmful stimuli, such as irritants or pathogens.
Inflammation is a protective response that helps the body rid itself of the offending stimuli and protect the body. However, if inflammation persists, it can damage the cells and tissues it is designed to protect.
Inflammation also occurs in the brain, and although some of this inflammation may be protective, researchers are interested in whether chronic inflammation might influence the development of mental disorders.
Although there is now good evidence of links between inflammation and depression, less research has examined the relationship between inflammation and anxiety.
Steadily, scientists are building up a body of evidence.
Because these conditions involve low grade systemic inflammation and because depression often comes hand in hand with anxiety, some scientists are asking whether inflammation might therefore play a part in anxiety disorders.
When investigating inflammation, scientists hone in on key markers in the body. Markers of interest include C-reactive protein (CRP), interleukin-6 (IL-6), and tumor-necrosis factor (TNF)-alpha.
CRP is released from the liver in response to inflammation. Its primary role is to bind to markers on dead or dying cells or microorganisms. Scientists believe that by binding to its target, CRP aids the complement system, which enhances immune cells’ ability to clear away pathogens and dead cells.