In theory, medicine works like this. You get some signs or symptoms. You go to the doctor, and depending on those, you get a diagnosis. Your doctor decides on the best available treatment on that basis.
The logic of this system depends upon the sequence. A diagnosis is meant to be an objective statement about the nature of your illness; treatments (if any) come afterwards. It would be odd if the treatments on offer influenced what diagnosis you got.
An interesting paper just out suggests that exactly this kind of reverse influence has happened. The authors looked at what happened in the USA in 2003 when antidepressants were slapped with a "black box" warning, cautioning against their use in children and adolescents, due to concerns over suicide in young people.
They used the data from the annual National Ambulatory Medical Care Survey (NAMCS) and the National Hospital Ambulatory Medical Care Survey (NHAMCS). These record data on the number of patients visiting their doctor regarding different illnesses, and what medications were prescribed if any.
What happened? The warning led to a reduction in the use of antidepressants. No surprise there, but unexpectedly, this wasn't because teens who visited their doctor regarding depression, were less likely to get given these drugs.
Actually, the proportion of depression visits, that were also antidepressant visits, was almost unchanged:
The proportion of depression visits with an antidepressant prescribed, having risen from 54% in 1998–1999 to 66% in 2002–2003, remained stable in 2004–2005 (65%) and in 2006–2007 (64%)
The difference was caused by a reduction in the number of teens getting diagnosed with depression - or rather, the number of visits where depression was mentioned; we can't tell if this meant doctors were less likely to diagnose, or patients were less likely to complain, or whatever.
This graph shows the story. After 2003, both antidepressant visits and depression visits fall, while the proportion of "antidepressant & depression" visits to the total depression visits (purple line), is constant.
The effect seen is just a correlation - it might have been a coincidence that all this happened after the black box warning in 2003. It seems very likely to be causal, though. Antidepressant use was rising steadily up until that point - and in adults, both depression and antidepressant visits rose after 2003.
It's also dangerous to pile too many heavy conclusions on the back of one study. But having said that -
Getting diagnosed with depression - at least if you're a teenager in the USA - is not just a function of having certain symptoms. The treatments on offer are a factor in determining whether you're diagnosed.
One alternative view, is that the fall in depression visits represents the fact that kids on antidepressants tend to have multiple visits - in order to monitor their progress, adjust dosage etc. So when antidepressant use fell, the number of visits fell. But if it were true, we'd presumably expect to see a fall in the proportion of visits that dealt with antidepressants, which we didn't.
This is disturbing either way you look at it. If you think the pre-2003 diagnoses were appropriate, then after 2003, kids must have been going undiagnosed with depression. On the other hand, if you think post-2003 was a welcome move away from over-diagnosis of depression, then pre-2003 must have been bad.
As to what happened to the kids who would have got a diagnosis of depression post-2003 were it not for the black box warning, we've got no way of knowing.
Why did this happen? Psychologist Abraham Maslow famously said"It's tempting, if the only tool you have is a hammer, to treat everything as if it were a nail." The history of psychiatrybears this out.
Sigmund Freud's psychoanalysis was essentially the theory that most mental disturbance was a 'neurosis' or 'complex' of the kind that's best treated by lying on a coach and talking about your dreams and your childhood, which as luck would have it, was exactly what Freud had just invented.
Along came psychiatric drugs, and suddenly everything was a 'chemical imbalance'. I've previously suggested that the invention of SSRI antidepressants, in particular, may have changed the concept of depression into one which was most amenable to treatment with SSRIs.
We always think we've hit the nail on the head.
Chen SY, & Toh S (2011). National trends in prescribing antidepressants before and after an FDA advisory on suicidality risk in youths. Psychiatric services (Washington, D.C.), 62 (7), 727-33 PMID: 21724784