People with depression have high concentrations of norepinephrine, a nervous system hormone that signals blood vessels to constrict and ratchets up blood pressure, researchers report. Treating these individuals with electroshock therapy lowers their norepinephrine concentrations—and their heart rate and blood pressure too, scientists find.
A fast pulse, vessel constriction, and high blood pressure are valuable tools in a person's fight-or-flight response. But if high norepinephrine concentrations chronically keep a person in that state, it puts a strain on the heart, says Mitchel A. Kling, a psychiatrist at the National Institute of Mental Health in Bethesda, Md. Excess norepinephrine, he says, could partly explain the long-standing connection between depression and heart failure, which is a weakening of the heart. Depression doubles the risk of death in people with heart failure, as do high norepinephrine concentrations.