Depression has so far been studied from a psychological perspective but a new study that was conducted by researchers at Canada’s Concordia University suggested that depression can have deeper physiological consequences as well.
The study looked at the stress system response of persons with mood disorders and depression and found flaws in the system that could lead to the onset of heart disease later on. The risk was estimated to be two times more for depressed persons than those who did not experience mood disorders.
The stress system response of persons was tested after the participants were made to undergo a stress test. Then their recovery heart rate was taken. Recovery heart rate refers to the rate of the heart measured at fixed intervals of time (usually after every passing minute) after some peak activity level has been stopped.
A greater reduction in recovery heart rate means the heart is in good condition as it is taking lesser time to recover from peak activity levels and thereby spiked heart rate to normal heart rate. It was found that for depressed persons who were put on the stress test, the recovery heart rate was less. This is to say, their heart took longer time to stabilize back to normal heart rate after exertive exercises. (1)
Thus the findings suggested that a dysfunctional or a sub-optimally functioning biological stress system was involved for those who experienced depression. As per first author of the study, Jennifer Gordon, PhD McGill University, “There have been two competing theories as to why depression is linked to cardiovascular disease. Depressed people may have poorer health behaviours, which may in turn lead to heart problems. The other possibility is physiological: a problem with the stress system known as the fight or flight response.” (2)
From out of the 886 participants averaging around 60 years of age who were examined, approximately 5 percent were diagnosed with major depressive disorder. Their heart rate and blood pressure were measured after the stress test along with those who were not depressive. It was found that the hearts of all those suffering from depression had taken longer to return to normal.