A new study by researchers in Canada has uncovered a link between clinical depression and inflammation. Inflammation is the body's protective response to microbial invasion or injury, but there's growing evidence that inflammation may play an important role in mental health.
The findings by researchers at the Center for Addiction and Mental Health (CAMH) and others suggest clinical depression might someday be treated with ordinary over-the-counter drugs, like aspirin and ibuprofen, that are currently used to fight inflammation.
In a small study involving 20 people with clinical depression and 20 healthy subjects for comparison, three-dimensional images of the functional processes in the body showed that patients with the mental disorder had a higher rate of inflammation in their brain.
Jeffrey Meyer, who heads the neurochemical imaging program at CAMH, says they used a dye that stuck to certain brain cells -- called microglia -- that play a key role in the brain's inflammatory response.
"We found that the elevation of this marker in people with clinical depression was quite elevated," he said. "Thirty percent in the area of depression research is a large magnitude level of difference."
Depression is a leading cause of loss of life and lower quality of life. Experts say more than half of patients with the disorder do not respond to antidepressants.
Meyer says people suffering from depression and a second condition associated with inflammation, such as heart disease and diabetes, have an especially difficult time.
"People who have other illnesses tend to be less responsive to conventional treatment," he said.
Last year, as they analyzed 14 international studies of over-the-counter pain medication use by patients with depression, Danish researchers made an intriguing discovery.
Ole Kohler, a medical student at Aarhaus University and lead author of the study, says anti-inflammatory drugs, taken on a regular basis to fight pain, seemed to boost the action of antidepressant medications.
"They had a better and quicker effect when they were used in combination," he said.
Kohler says blood tests, looking for markers of inflammation, seem to support the benefits of anti-inflammatory drug use in patients with clinical depression.
"There are more often increased markers of inflammation in the peripheral blood," he said. "So there is some kind of inflammatory reaction going on in some depressed individuals."
Canadian researchers, meanwhile, are investigating whether short-term use of minocycline, an antibiotic with anti-inflammatory properties, improves the mood of people suffering from depression.