Researchers have identified an enzyme that may trigger depressive symptoms in patients with heart disease and may help to explain why general antidepressants are often not as effective for these specific patients.
"Our study confirms that depressive symptoms are associated with inflammation in patients with heart disease and suggests a mechanism by which the brain might be affected," says Walter Swardfager, lead author of a new study and PhD candidate in the Neuropsychopharmacology Research Program at Sunnybrook Health Sciences Centre.
The research focuses on an enzyme that is part of the inflammatory process in patients with coronary artery disease (CAD). The enzyme breaks down the amino acid tryptophan and it is associated with damage to brain cells. Findings show a significant association between activation of this enzyme and the degree of depressive symptoms in these patients. They also identify a trend towards even higher levels in those suffering from clinical depression.
"This enzyme makes 'brain unfriendly' chemicals," says Dr. Krista Lanctôt, principal investigator and head of the Neuropsychopharmacology Research Program at Sunnybrook. "We are trying to chase down a treatment for patients with CAD that will block the enzyme and/or prevent the inflammatory process in the first place."