Wednesday, January 20, 2010
Depression and Inflammation: The Surprising Link
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.