Inflammation and Depression - new link?

Once again - the role of inflammation in our mental and physical health is becoming more and more apparent. And just in case you haven't seen me say this more and more often recently, let me remind everyone that inflammation is a natural response of our immune system to danger, injury, or illness. Unfortunately, it is also a response to the long-term stress of trauma, emotional repression, and, recently, of just trying to survive in today's increasingly dysfunctional world.

The stress response, including inflammation, was never meant to be engaged long term. Doing so makes us ill.

Anyway, I love my National Geographic subscription - so many great articles on so many different subjects, and of course their famous photography. One of the main subject categories is health, and this is where I often learn about neuroscientific breakthroughs. This is the latest one, and folks, it is really exciting!

This link (in the title below) might be behind a paywall, which I must respect, but I will excerpt some key paragraphs and statements.

Can ending inflammation help win our battle against depression?
Multiple lines of research suggest that inflammation in the body can affect the brain and alter mood—a finding that could lead to new solutions for hard-to-treat issues.

National Geographic Magazine
By Emily Sohn
November 1, 2023
[excerpts only]

Chronic illness can be tough on mental health. Depression affects 42 percent of cancer patients, according to the Centers for Diseases Control and Prevention, as many as 42 percent of people with rheumatoid arthritis, 27 percent with diabetes, 17 percent with cardiovascular disease, and 11 percent of Alzheimer’s patients. [Jan edit: ask yourself: chicken, or egg?]

There is something else those diseases share: inflammation. And that’s not a coincidence. In many cases, scientists are finding that inflammation exacerbates mental health beyond the challenges of living with a chronic illness.

“We're at the stage where we have a number of different types of evidence that all point toward either a heightened inflammatory response or at least an altered immune response being involved in our future risk of depression, our current state of depression, and our response to treatment for depression,” says Wolfgang Marx, an expert in nutritional psychiatry at Deakin University’s Food & Mood Centre in Melbourne, Australia. “All along the pathway of that clinical course of depression, inflammation seems to play at least some sort of role.”

Depression was, for a long time, considered to be a simple story of neurotransmitters gone wrong...
... In the last few decades, however, multiple lines of evidence have converged to suggest that, while neurotransmitters matter, the immune system also plays a role in affecting mental health and that inflammation in the body can alter mood in the brain.
... As scientific knowledge has exploded about the number of molecules involved in the inflammatory process, so too have studies linking a variety of inflammatory cytokines with major depressive disorder, as well as bipolar disorder and schizophrenia.

Uncovering how exactly inflammation damages mental health is a work in progress, and scientists are investigating several hypotheses. Among them... that chronic inflammation may impair the production of serotonin and other neurotransmitters, inhibit the body’s ability to make new brain cells, or damage the ability of brain cells to make new connections with each other. Impacts are particularly notable in the hippocampus, the part of the brain that is responsible for memory, emotional regulation, and mood...

To understand how inflammation-related depression develops, some researchers are looking to key risk factors for depression in the earliest stages of life. Scientists have known for decades that a history of trauma in childhood raises the risk for adult depression in general and treatment-resistant depression in particular. Inflammation may help explain the association and might be the key to mitigating it...
... Kids who experience abuse and neglect in the first decade of life show elevated levels of several inflammatory molecules by the time they are in their early thirties...
Childhood maltreatment—and chronic inflammation—are also associated with a heightened risk for cardiovascular disease, type 2 diabetes, and other physical health conditions.
... early life stress related to childhood maltreatment might affect brain development in multiple ways—through activated inflammatory pathways—that lead to long-lasting impacts. Exacerbating that connection are substance misuse, unbalanced diet, poor sleep, and other behaviors related to maltreatment that can also increase inflammation.
... Chronic stress activates inflammatory circuits at any age, studies show, but exposure to stress at an early age appears to cause more stubborn forms of depression... Identifying the pathways involved provides a window into opportunities to buffer the damaging effects of childhood maltreatment and improve treatments for people with a history of depression. “Individuals who have a history of childhood maltreatment tend to have more chronic and more persistent types of depression and they also tend to respond more poorly to conventional treatment...” “Inflammation may definitely be one of the biological reasons for why this happens.”

As scientists unravel the details of inflammation’s role in mental health, they are looking for ways to fight depression by controlling inflammation. The strategy appears to be most promising for the estimated 30 percent of people with depression who don’t respond to standard anti-depressants. This group, studies show, tend to have the most elevated inflammation levels.

Many mood stabilizers and mental-health medications already have anti-inflammatory effects. And a wide variety of anti-inflammatory medications appear to ease depression, found a 2019 review of research...

Multiple approaches are welcome, Marx says, because mental health is complicated. The risk for depression is tied to genetics, biology, environmental factors, and life experience, and mood is wrapped up in many processes in the brain and body. Inflammation is only part of the story; it is elevated in at most half of people with depression. And it probably goes both ways, Marx adds, with depression leading to inflammation, too. But the strong and growing evidence linking inflammation with depression suggests that many people could benefit from addressing chronic inflammation as a mental-health strategy. And medications aren’t always necessary.
...Among lifestyle changes that can affect mental health, including exercise, diet might be one powerful way to intervene, Marx says. Mediterranean-style eating, in particular, has been linked through multiple studies to a reduction in depression symptoms... reported in a 2020 review of research.
... Evidence also supports sufficient sleep, spending time outside, and reducing stress through meditation as ways to lower inflammation and in turn, boost mood.

“As we learn more about the role that lifestyle factors have to play in our mental health and also in inflammation, I think that provides quite an empowering message,” Marx says. “By exercising, by engaging with nature, by eating healthily, we can actually make a pretty substantial difference—not only in physical outcomes, but also our mental health.”​