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Depression too often reduced to a checklist of symptoms

Depression too often reduced to a checklist of symptoms

How can you tell if someone is depressed? The Diagnostic and Statistical Manual of Mental Disorders (DSM) – the ‘bible’ of psychiatry – diagnoses depression when patients tick off a certain number of symptoms on the DSM checklist. A large-scale quantitative study coordinated at KU Leuven, Belgium, now shows that some symptoms play a much bigger role than others in driving depression, and that the symptoms listed in DSM may not be the most useful ones.

To diagnose depression, psychiatrists typically tally up the number of depression symptoms that patients report in questionnaires. It does not matter which of the symptoms these patients have, as long as they have a certain number of them.

A new study challenges that approach.

“We need to stop thinking of depression as a disease that causes a number of interchangeable symptoms”, says lead author Dr Eiko Fried from the KU Leuven Faculty of Psychology and Educational Sciences.

“Depression is a complex, extremely heterogeneous system of interacting symptoms. And some of these symptoms may be far more important than others”.

The researchers analysed data on 28 symptoms provided by 3463 depressed patients. They then examined the connections between these symptoms. Their network analysis shows that some symptoms are more ‘central’ – more connected – than others. As a result, these symptoms have a much bigger impact on the depressive process.

“If you think of depression as a network of interacting symptoms, one symptom can cause another”, Fried clarifies.

“For instance, insomnia may lead to fatigue, which in turn may cause concentration problems that feed back into insomnia. This example of a vicious circle shows that the specific symptoms patients report, and their interactions, can be of crucial clinical importance”.

“Depression is not like, say, measles. When you have measles, your symptoms help the doctor figure out what underlying disease you have. But once you are diagnosed, it doesn’t really matter which of the possible symptoms you did or didn’t get. Treating the disease itself makes all your symptoms disappear.”

“Depression is more complicated. It is not an infection or a specific brain disease. There is no easy cure, no drug that makes all symptoms go away. Instead, we may want to focus treatment efforts on the symptoms driving a patient’s depression”.

In the study, the two main DSM symptoms – sad mood and decreased interest or pleasure – ranked among the top 5 in terms of centrality. But the researchers also found that DSM symptoms such as hypersomnia, agitation, and weight change are not more central than other common depression symptoms such as pessimism and anxiety.

So where does that leave psychiatry? Has the time come to chuck the DSM checklist of depression symptoms?

“Ideally, the list of depression symptoms should become more comprehensive to do justice to the heterogeneity of depression. I also think both clinicians and researchers can learn a lot from paying more attention to individual symptoms and their interactions.”

“But of course, we need much more research before we can actually replace the DSM diagnosis of depression with something else”.

Sources:
Fried, E., Epskamp, S., Nesse, R., Tuerlinckx, F., & Borsboom, D. (2015). What are ‘good’ depression symptoms? Comparing the centrality of DSM and non-DSM symptoms of depression in a network analysis Journal of Affective Disorders DOI: 10.1016/j.jad.2015.09.005

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3 responses

  1. Hello Lunatic Laboratories. It is interesting to consider the parabola graph of statistical infrequency with regards to the diagnosis of mental illnesses. For rarer illnesses, the statistical approach graph can be useful to highlight ‘abnormalities’ relative to a particular cultures’ social norms. However, depression is relatively common, with about 1 in 4 people experiencing depression at some point in their life. This means it is hard to spot on a bell curve. What would you say then, is the best way to diagnose mental health disorders, such as depression?

    October 25, 2015 at 9:52 am

  2. Candice Coleman

    The brain, along with depression, can be a tricky thing to understand completely. Depression is commonly a result of stressful events. The brain controls the response to a stressful event and depending on the situation, certain chemicals in the brain will increase. I understand that not all people who have depression got it from a stressful event, but I used that example to make my point. My point is this: depression cannot be confined to a list of symptoms. I believe this article clearly proves that point. I agree with Dr. Eiko Fried when he says that depression is complex and that there is no easy cure. So what is the answer to figuring out how to define and cure depression? More research on the disorder. This may not be the answer people want to hear but for now it is all we can do.

    October 30, 2015 at 11:28 am

    • Completely agree, we can’t figure out a better way until we actually understand what is going on in the brain. To highlight how little we know, look at the method of action for most antidepressants and you will typically find a line like “although the method of action is unknown, it is thought that drug ” X” inhibits the re-uptake of neurotransmitter “Y.”

      Frankly it’s a little (pardon the turn of phrase) depressing.

      October 30, 2015 at 11:33 am

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