If depression is an evolved adaptation to stress, the immediate question is what possible benefit it could bring. As discussed in the Depression Reflex, it makes evolutionary sense for a creature hit by defeat, loss, or injury to withdraw – a strategic retreat that stops a bad situation from becoming worse.
Just as the ordeals of pregnancy and labour are over – right when a mother expects joy and blissful repose – there is an illness that not only feels dreadful but also impairs her ability to be the happy, adept, and loving carer she hoped to be. With mood low, energy gone and thinking foggy, normal tasks suddenly seem impossible, let alone providing the expected perfect welcome to a demanding new arrival.
Doctors generally view diagnoses as discrete, well-defined entities. You either have malaria, or you do not. You are pregnant, or you are not. There is no in-between. Settling upon one also rules out the others. For example, if a CT on a patient with a splitting headache shows a brain tumour, that’s the diagnosis.
During the Blitz of World War II, Londoners faced the terror of nightly bombardment that left 43,000 dead and millions homeless. The Nazis expected to destroy morale and force surrender, yet the British chose to fight on and among the people there was a surprising absence of crime and suicide. Not only did the expected panic and despair never materialise, but the people appeared to rise to a new level of unity and resilience.
Depression comes in many forms and affects all walks of life. Genes and experiences interweave to produce an emotional and physical response as crippling as a serious disease. While the cause remains elusive, through many years of research one finding is rock solid: women are affected around twice as much as men. Often the discrepancy is blamed on gender-based discrimination: women are more depressed, the theory goes, because they have fewer advantages and more hardships in a patriarchal society.
Scientists have long observed an association between depression and heart disease. Depressed adults have a 66% greater risk of developing coronary artery disease. These patients are also more likely to progress to serious outcomes such as a heart attack – at least a quarter of cardiac patients suffer with depression.