It must be incredibly difficult to imagine the maddening reality of living with a mental illness for someone who has never experienced it first hand. We all feel blue from time to time, but few ever experience the debilitating inability to feel joy, constant fatigue, and mind-numbing impediment of thought accompanied by major depressive disorder. William Styron once described it as being attached to a bed of nails which one carries around wherever they go, and in my experience this is strikingly accurate.
Yet for all its unpleasantness the noonday demon seems to pose an evolutionary paradox. Darwin’s legacy was that evolutionary pressures shape not only our physical characteristics but our mental and behavioural processes as well. This being the case, how is it that an illness characterized by a myriad of symptoms so obviously detrimental to evolutionary fitness – decreased cognitive function, a loss of interest in sex, socializing, and exercise, not to mention suicide – has persisted?
Not only has depression not been wiped out through the course of natural selection, it is now – and I believe rightly so – considered an epidemic. The global burden of depression is soaring; the latest estimates by the World Health Organization place the global prevalence of depression at three hundred and fifty million worldwide , and in the last forty five years alone the annual rate of suicide has increased by sixty percent . Despite our best efforts in the development of behavioural therapy, pharmacological treatment, and psychological theory the depression epidemic shows no signs of letting up. We are losing the fight against depression.