This is not a new story, but it's new to me, and its logic compells: Molecular research shows that the receptor that governs what we think of as depression has deep mammalian roots, which means it must have been selected for by evolution. So why would depression be useful?
Depressed people often think intensely about their problems. These thoughts are called ruminations; they are persistent and depressed people have difficulty thinking about anything else. Numerousstudieshave also shown that this thinking style is often highly analytical. They dwell on a complex problem, breaking it down into smaller components, which are considered one at a time.
This analytical style of thought, of course, can be very productive. Each component is not as difficult, so the problem becomes more tractable. Indeed, when you are faced with a difficult problem, such as a math problem, feeling depressed is often a useful response that may help you analyze and solve it. For instance, in some of our research, we have found evidence that people who get more depressed while they are working on complex problems in an intelligence test tend to score higher on the test.
I can attest recently to feeling depressed in just this way, while trying to write a difficult story over a weekend. Just as authors of this study, Paul Andrews and J. Anderson Thompson Jr, said, this depressed mood led to intense concentration and disinterest in food, sex, or pleasure, or anything but the problem, in fact, and the non-stop thinking did lead to a solution. (Sez me.)
But is there any evidence that depression is useful in analyzing complex problems? For one thing, if depressive rumination were harmful, as most clinicians and researchers assume, then bouts of depression should be slower to resolve when people are given interventions that encourage rumination, such as having them write about their strongest thoughts and feelings. However, the opposite appears to be true. Severalstudieshave found that expressive writing promotes quicker resolution of depression, and they suggest that this is because depressed people gain insight into their problems.
Would we be less troubled by depression if we thought of it as a form of problem-solving? Guess it depends on whether or not the problem can be solved by rumination.