Depression and Inflammation: The Surprising Link

Depression is risk factor for depression. Researchers have known that for many years but couldn't really explain why—until now.

In the past 10 years, researchers have firmly established that a lot of common diseases--such as diabetes, cancer, Alzheimer’s, and yes, even heart disease--are due to inflammation. For example, physicians have noted that elevated levels of an inflammatory marked called C-reactive protein is an early harbinger of heart disease.

But here’s where the plot really thickens. Depression is also caused by inflammation, and specifically by elevated levels of molecules called proinflammatory cytokines. In fact, by specifically treating people with cytokines, as they do for conditions such as MS, doctors have actually caused depression. The more cytokines patients received, the more depressed they got. When the patients started to taper off of the cytokines, the depression got better too.

Depressed people have significantly higher levels of the cytokines in their plasma than non-depressed people. And this is where the disease-depression link comes from. High levels of proinflammatory cytokines damage blood vessels, and elevate other factors in the blood that increases the risk of clots.

And in another interesting twist, we now know that most of the effective treatments for depression have one thing in common: they are also anti-inflammatory. In fact, that knowledge has fueled some very interesting discoveries. For example, antidepressants lower inflammation levels in cardiac patients. And they’ve been added to steroids for treating asthma, leading to the use of fewer steroids in these patients.

This discovery has also led to some novel ways of treating depression. For example, anti-inflammatory medications, such as ibuprofen, which is not an antidepressant, have been added to antidepressants to make them more effective. Adding Omega-3 fatty acids to a treatment regimen helps with depression for the same reason.

Knowing about the anti-inflammatory connection also gives us a framework for understanding why non-medication treatments for depression would also work.

What’s Stress Got to Do With It?: The Many Ways That Stress Impacts Our Health

Health care providers often tell me that they came to my lectures to learn about something for their patients, but they ended up finding something useful for themselves. They could be suffering from chronic pain, or heart disease, or metabolic syndrome. But they didn’t know that psychological stress was often a key part of why they were sick--and could even kill them.

In one of the first major studies in this field, researchers noted that people who were taking care of spouses with Alzheimer’s were dying at higher than rates than their non-caregiving peers. They were developing heart disease and cancer and other fatal diseases. I often think of Christopher Reeves' wife. Had caring for her severely disabled husband contributed to her own early death?

Researchers have also studied the link between depression and heart disease. Did you know that depression is a well-known risk factor for heart disease? Or that depression, hostility and other negative mental states increases your risk of developing diabetes?

Along these same lines, researchers have discovered that depression, stress or anxiety during pregnancy dramatically increases the risk of preterm birth. We are now beginning to understand why that would be so.

Sleep problems are another fascinating area of study. A lot of people know that sleep problems increase this risk of heart disease and diabetes. But what you might not realize is why they do.

The answer to these questions has to do with how humans respond to stress. And that is the focus of our installment. Stay tuned!