I don’t think it’s necessary here to outline the effects that depression on individuals or on society. Loss of productivity, the ability to work, or even life itself are all too often the outcomes of this common disease.
There are two major and related questions within the medical community on depression. They are what causes depression and what are the best treatments. They are strongly related, as treatment of any disease is usually dependant upon cause.
Harriet Hall at Science Based Medicine has a look at a new book (now my next read) called The Depths: The Evolutionary Origins of the Depression Epidemic By Jonathan Rottenberg published by Basic Books. Rottenberg discusses depression as an adaption that helped our distant ancestors survive in the wild and has continued into the present where the altered environment has changed the value of the biological process. This idea is not new to biology as researchers have postulated evolutionary benefits for both allergies and obesity.
Low mood has its benefits. Non-depressed people tend to overestimate their abilities, are prone to positive illusions, and demonstrate overconfidence and blindness to faults. When depressed, people are more realistic; they are more deliberate, skeptical, and careful in processing information from the environment.
Low mood can be triggered in animals and humans by factors such as separation from the group, removal to an unfamiliar environment, the inability to escape from a stressful situation, the death of a significant other, scarce food resources, prolonged bodily pain, and social defeat. Low mood serves as an alarm system. It gets our attention and lets us know something is wrong. Depression allows us to stop, retreat to an emotional cocoon, analyze what went wrong, and hopefully change course to avoid future calamities.
This is the adaptive side of depression, and sounds reasonable for milder episodes where we become introspective without being debilitated.
But low mood has its costs, too. Whatever the benefits, there are plenty of negative effects like distorted thinking, delusions, suicide, difficulty in concentrating and functioning, and weakened executive functions in the brain.
A shallow depression can be adaptive, but a deep depression is maladaptive. There’s a continuum, and any cut-off point to divide normal from abnormal is arbitrary.
Rottenberg discuses how depression can happen or be induced in animals by increasing stress levels to a level that certain animals find intolerable. Individual animals and humans respond differently to prolonged stress with an estimated 30-40% of susceptibility to be genetic.
According to Rottenberg, depression arises not from a defect, but from what we do well: thinking, using language, holding onto ambitious goals, and even our drive to be happy. Rottenberg says “The picture of depression that emerges is richer, more interesting, and in some ways more troubling than defect-model approaches would allow.”
He offers clues about how low moods can be better managed: appreciating the costs of thinking, sometimes accepting a low mood with equanimity, aiming for goals that are high but not too high, knowing when it is time to give up on a goal, and realizing that happiness is not itself a goal but “a fleeting byproduct of progress towards other goals.” Despite the evolutionary directive to become depressed, we retain a margin of control to shape its course.
Currently, the best treatments for mild depression are cognitive therapies and lifestyle changes, while for more severe cases, the addition of drugs is more successful. Will Rottenberg’s theories have a role to play in the future treatment of depression? It’s much too soon to say. What is important however, is that extending the chemical model of depression to include evolutionary science might help to remove the stigma that accompanies mental illness.
Many of us suffer for many years without being able to express our disability with our personal and professional cohorts. The consequences are often isolation or loss of work, or worse. One of the keys to dealing with depression is to accept it in ourselves and minimize the fear of being rejected in society.
The Depths: The Evolutionary Origins of the Depression Epidemic is available in hardcover, electronic, and audio formats.