In the early 20th century, the idea that mental illness was caused by chronic infection was widespread and, for the most part, accepted. Psychiatrists such as Henry Cotton from the New Jersey State Hospital at Trenton, took this idea and attempted to cure his patients by removing areas of infection: decaying teeth, tonsils, colons and even ovaries and testicles. Looking back with the information we have now about neurotransmitters, Cotton’s approach seems somewhat archaic. However, new evidence showing a link between inflammation and mental illness support the idea that infection is related, specifically for mood disorders like depression.
For the most part, imbalances in the neurotransmitter serotonin are what are thought to cause depression. Recently, though, studies have demonstrated elevated inflammatory responses in patients with depression. Inflammation is a reaction from our immune system to a harmful stimulus or cell. Our immune system, though, cannot differentiate between what is activating it. An infection may activate our system and then, for unknown reasons, may continue to create an inflammatory response that impacts our psychiatric state.
A professor at the University of Toronto explains that even infection in the womb can lead to heightened risks of mental illness such as depression, bipolar disorder and schizophrenia if more inflammatory responses occur later in life. A Danish study showed that people hospitalized for an infection were 62 percent more likely to later develop a mood disorder. There is a large correlation between inflammation and mental illness.
The next step is figuring out what this means for the treatment and prevention of mental illness. Currently, selective serotonin reuptake inhibitors are the most common type of medication-based treatment for mood disorders. It is possible, though, that the addition of certain anti-inflammatory drugs could provide aid to patients. Anti-inflammatory drugs will be more successful for some people than others, just as is the case with SSRIs. Important to note, too, is the immune-based treatments that are going to have big impacts on mood disorders most likely have not been discovered yet.
Linking infection and inflammation with mood disorders marks a huge step in fighting the stigma surrounding mental health. Infection is a physical indicator of illness, something that most mood disorders do not have. Having a physical connection with mental illness could allow people to more easily see it as something that cannot necessarily be controlled. You do not choose when you get sick or break an arm, just like you do not choose when you become depressed.