Inflammation may have link with increase in depression

By Drs. Kay Judge and Maxine Barish-Wreden Published: November 13, 2012
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The incidence of depression has skyrocketed in children and adults since World War II. Depression affects about 10 percent of the population in the United States, and the World Health Organization predicts that by 2030 more people will suffer from depression than any other medical condition.

Antidepressant medication use has also increased (to the tune of 400 percent) since the 1980s, when drugs such as Prozac hit the market, even though recent data suggest that these medications offer little if any benefit to people with mild to moderate depression.

Despite this, the Centers for Disease Control and Prevention reported in 2011 that 11 percent of Americans over the age of 12 take antidepressants.

Why has there been such a dramatic increase in depression?

Although traumatic life events, stress and social isolation can increase the risk of depression, our Western way of life is probably a bigger contributor. Evidence suggests that nutrient-poor diets high in refined carbohydrates and commercially raised animal foods, combined with lack of exercise, all contribute to obesity, heart disease and diabetes.

These diseases are associated with elevated levels of inflammatory markers in the blood such as C-reactive protein, and they are also all associated with depression. People with other inflammatory disorders such as rheumatoid arthritis are also at increased risk of depression.

Could inflammatory changes in the brain be one of the main drivers behind our epidemic of depression? And could this explain why antidepressant medications often don't work for people with depression?

This is an exciting new area of research.

In pursuit of the inflammation-depression connection, researchers from Emory University in Atlanta looked at the use of an anti-inflammatory drug called infliximab for the treatment of major depression in people who had not responded to antidepressants. Infliximab, also known as Remicade, is usually given to people with inflammatory disorders such as rheumatoid arthritis, inflammatory bowel disease and psoriasis.

The researchers in the study found that 62 percent of depressed people with high blood levels of C-reactive protein had a reduction in their depression while taking the infliximab, while only 33 percent of those with normal CRP levels noted improvement. This was the first time that a drug specifically targeting inflammation was used to successfully treat depression, and provides some support for the depression-inflammation theory.

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