Is “depression” one condition or several? A reader’s doubts
Its coordinates: 6.14 Philosophy of Psychology
One question has followed me through years of my own analysis and of reading psychiatry: when two people receive the same diagnosis of major depression, do they have the same thing?
Consider how the diagnosis works. A person needs five of nine listed symptoms over two weeks, one of which must be low mood or loss of interest. Do the arithmetic and two people can both meet the criteria while sharing only a single symptom. One sleeps all day, eats constantly and moves slowly; the other cannot sleep, has lost weight and is agitated.
If the category tracks one underlying condition, research should converge on a mechanism and a treatment. If it bundles several conditions that look alike, every study sample will contain a different mix, effects will be modest and inconsistent, and no treatment will work for everyone. The second pattern is, roughly, what we see.
Psychoanalysis has its own way of saying this, of course: analysts ask about the structure behind a symptom, not the symptom count. But I don't want to score points for my tradition, which has its own replication problems.
The other complication is the one Ian Hacking called the looping effect. People who receive a diagnosis learn its description and sometimes come to live inside it, which changes what the category describes.
So: is depression a natural kind, several kinds, or something we are partly making as we name it? I'd like to hear from researchers, clinicians and people who have been diagnosed.