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Saturday, January 30, 2010

Is Depression Undertreated?

Neuroskeptic readers will be familiar with the idea that too many people are being treated for mental illness. But not everyone agrees. Many people argue that common mental illnesses, such as depression, are undertreated. Take, for example, a paper just out in the esteemed Archives of General Psychiatry: Depression Care in the United States: Too Little for Too Few.

The authors looked at the results of three large (total N=15,762) surveys designed to measure the prevalence of mental illness in American adults. I've described how these surveys are conducted before: they took a randomly selected representative sample of Americans, and asked them a standardized series of questions (the CIDI interview) about their mood and emotions, in order to try to diagnose mental illness. The interviewers, while trained, were not clinicians.

What did they find? The rate of people experiencing Major Depressive Disorder (MDD), as defined in DSM-IV, in the past year, was 8.3%. When they examined ethnicity, this ranged from 6.7% in African Americans to 11.8% in Puerto Ricans. The average severity of the depression was roughly the same in all ethnic groups.

Of those with MDD, 51% reported that they'd had treatment in the past year, either antidepressants, psychotherapy, or both. This ranged from 53% for Whites down to just 29% of Caribbean Blacks and 33% of Mexican Americans. Therapy was somewhat more popular than drugs in all ethnic groups, although a lot of people used both. However, few of the treatments were classed as "guideline-concordant", i.e. long enough to do any good, which they defined as
use of an antidepressant for at least 60 days with supervision by a psychiatrist, or other prescribing clinician, for at least 4 visits in the past year. For psychotherapy...having at least 4 visits to a mental health professional in the past year lasting on average for at least 30 minutes each.
Only 21% of depressed people were getting such treatment, even though these strike me as very lenient guidelines, especially in the case of psychotherapy - how much good is 2 hours per year doing to do?


So depression's undertreated, especially in minorities. Too little, for too few. But this rests on an assumption: that we should treat Major Depressive Disorder.

That might not seem like an assumption, but assumptions generally don't. It seems like common sense, almost a tautology - it's a disorder, of course we should treat it! Yet it's not so simple. DSM-IV criteria for MDD require you to have 5 or more out of a list of 9 symptoms, including either depressed mood or a loss of interest in activities, lasting at least 2 weeks, and causing significant distress or impairment in social, occupational, or other important areas of functioning.

Fair enough. That's quite useful as a way of ensuring that psychiatrists in different countries are talking about the same thing when they talk about depression. But to think that depression is undertreated because only half of people meeting DSM-IV criteria for Major Depressive Disorder are being treated, is to put absolute faith in DSM-IV as a guide to who to treat. This is not what the DSM was meant to be, and there's no evidence it works for that purpose.

Is it really true that people with 5 symptoms need help, and those with 4 don't? Why not 6, or all 9? Why 2 weeks - why not 3 weeks, or 3 months? It's not as if there are loads of studies showing that treating people who have 5 symptoms for 2 weeks, and not treating people who don't, is the best strategy. I'm not aware of any such research. In particular, there's no evidence that people from the general population who meet these criteria when interviewed, but don't seek treatment, would all benefit from treatment as opposed to being left alone. Certainly some would, but they may be a minority.

This is not to say that any other criteria would be better than DSM-IV as guides to treatment, or that there is anything identifiably wrong with the DSM-IV criteria (although there is evidence that antidepressants are not useful in people with relatively "mild" MDD). The point is that doctors don't strictly apply textbook criteria when diagnosing and treating mental illness; they also use clinical judgement.

I don't know any psychiatrist who would prescribe treatment for someone solely on the basis that they met DSM-IV criteria for MDD. They would also want to know about the severity of the symptoms, whether they're related to any stresses or life events, how far they're "out of character" for that individual, etc. In general, they would deploy their training and experience to try to judge whether this person would benefit from treatment. This is why the DSM-IV carries a cautionary statement that "The proper use of these criteria requires specialized clinical training that provides both a body of knowledge and clinical skills."

So, it's far from clear that we should be treating everyone who answers interview questions in such a way that they meet DSM-IV criteria for Major Depressive Disorder. That's an assumption.

This isn't to say that everyone who needs depression treatment gets it. Sadly, there are many sufferers who would benefit from help and don't get any, or don't get it as early as they should. We need to do more to help such people. In this respect, depression is undertreated, although it's hard to know the extent of the problem. Yet it's quite possible that depression is also overtreated at the same time.

H/T Thanks to The Neurocritic for drawing my attention to this paper.

ResearchBlogging.orgGonzalez, H., Vega, W., Williams, D., Tarraf, W., West, B., & Neighbors, H. (2010). Depression Care in the United States: Too Little for Too Few Archives of General Psychiatry, 67 (1), 37-46 DOI: 10.1001/archgenpsychiatry.2009.168

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