When Does Depression Become A Disease?

By Neuroskeptic | March 15, 2013 9:30 am

When does sadness cease to be a normal emotional response, and become a mental disorder? Can psychiatrists ‘draw the line’ between healthy and sick moods, and if so, where?

An important new study offers an answer: When does depression become a disorder? Using recurrence rates to evaluate the validity of proposed changes in major depression diagnostic thresholds (free pdf).

The authors, Jerome Wakefield and Mark Schmitz of New York, made use of the ECA survey, a 1980s study of almost 20,000 American adults. Participants were surveyed twice each, approximately one year apart. On each occasion, they were asked questions about their mood, emotions, and mental health symptoms.

Some people reported a history of depression at the first visit. Wakefield & Schmitz wanted to find a way of predicting which of those people were most likely to end up depressed at the time of the second interview, a year later – the recurrence rate. To do this, they examined the particular patterns of symptoms reported at the first visit.

It turned out that there was a strong predictor of recurrence, which the authors call “complicated” depression. People with a history of complicated depression had a 15% chance of being depressed at follow up. Only 3.4% of those who’d had “uncomplicated” symptoms, however, were depressed a year later. Given that 1.7% of people with no depression history had become unwell by Time 2, this means that “uncomplicated” depression was almost never recurrent.

So what exactly is “uncomplicated” depression? The criteria were: episodes that last no longer than 2 months, and that do not include suicidal feelings, psychotic symptoms, psychomotor retardation, or feelings of worthlessness. If any of those symptoms were present, or if the low mood lasted longer than 8 weeks, it was classed as “complicated”.

Now, the concept of a “complicated” mood episode is actually a pretty old one in psychiatry, but it was originally intended to only apply to bereavement. An “uncomplicated” bereavement was regarded as a normal reaction to a loved one’s death; only if grief was characterized by certain symptoms was it seen as “complicated” by depression.

According to Wakefield & Schmitz, this complicated/uncomplicated distinction is so important that it can be applied to all potential cases of depression – not just bereavements. The implication is that episodes of low mood that last less than two months, and that are free of certain symptoms, are not pathological, in the sense that they don’t predict future illness.

Neuroskeptic readers may remember the background to this. Two years ago, I blogged about first author Jerome Wakefield’s criticisms of the American Psychiatric Association (APA)’s upcoming DSM-5 criteria.

Back then, Wakefield was arguing against the APA’s decision to scrap the ‘bereavement exclusion’ to the depression criteria. The bereavement exclusion says that low mood doesn’t count as depression if it happens in the context of grief… unless the symptoms are “complicated”, as we’ve seen. DSM-5 is set to get rid of the grief exclusion and, as a side effect, also the complicated/uncomplicated distinction.

ResearchBlogging.orgWakefield JC, & Schmitz MF (2013). When does depression become a disorder? Using recurrence rates to evaluate the validity of proposed changes in major depression diagnostic thresholds. World Psychiatry, 12 (1), 44-52 PMID: 23471801

  • http://twitter.com/MancPsychSoc MancPsychSoc

    Nice blog and nice paper. It’s an interesting probem that I think most medical students take for granted – how do we categorize dimensional phenomena? Although rife in psychiatry this problem extends to the rest of medicinemedicine – take hypertension for example?
    Although somewhat arbritrary, the cut off point for any clinical diagnosis will surely want to account for those symptoms/signs/results that best predict the health of the patient. But defining how we assess ‘health of the patient’ is not simple. This study only uses one criteria to assess that – a one year follow up of symptoms. Presumably, the ideal would be to integrate other criteria such as effects on cognition, quality of life, mortality, comorbidity etc?

    • http://jdeveland.com/ JD Eveland

      Good point. This issue also presents in my field – organizational psychology – perhaps even more strongly. Most group or organizational-level phenomena that we study – either constructs at that level or constructs created by aggregating individual-level measures – are scalar in form. However, there is a tendency to transform many of these into categories, particularly those used as control variables. Often there is little explanation offered for these categorizations; often it has more to do with simplifying the analysis than with any theoretical basis. Indeed, I know of no theory underlying categorizations other than some rules of thumb and heuristics passed down through the ageds. [That was supposed to be “ages”, but when I looked at the typo created by hitting two keys together, I thought it sufficiently entertaining to let it stand.]

  • Psychiatry Critic

    It’s interesting that some of the symptoms of complicated depression (such as psychomotor retardation and excessive guilt/feelings of worthlessness) are the same as those of melancholic depression, which has long been thought to be more “biologically-driven.” I wonder if this current article examined other features of melancholic depression (loss of appetite/wt loss, early morning awakening, severe anhedonia/affective flattening) to see if those also contribute to depression relapse.

    • http://blogs.discovermagazine.com/neuroskeptic/ Neuroskeptic

      As luck would have it, they did look at melancholic vs. nonmelancholic and the recurrence rates were 20% vs 10%. So melancholic depression had a high recurrence rate (higher than “complicated” which was 15%) but nonmelancholic was still quite high.

      • indigorhythms

        I think psychiatrists have viewed melancholic depression as the more severe variety but I’ve read a number of places that bipolar depression tends to be more atypical and has a higher rate of recurrence. This seemed to be particularly true for bipolar II. Personally my depression became more typical as I became older, so I wonder if they took that into consideration?

      • indigorhythms

        I think psychiatrists have viewed melancholic depression as the more severe variety but I’ve read a number of places that bipolar depression tends to be more atypical and has a higher rate of recurrence. This seemed to be particularly true for bipolar II. Personally my depression became more typical/melancholic as I became older, so I wonder if they took that into consideration?

  • Bernard Carroll

    Much as I admire the work of Dr. Wakefield, we should not
    regard this report as the last word on the subject. The primary data aren’t too
    reliable… lay interviewers as in the ECA project don’t match up too well with
    professional interviewers. As well, these subjects were selected on the basis
    of reported past episodes of depression, not on current depressive
    presentations. This condition also affects diagnostic and descriptive
    reliability.

    The definition of uncomplicated depression resulted in a
    surprisingly small cohort – only 12.5% or 88 of 704 cases. That isn’t what one
    would expect in an epidemiologic sample, which makes the generalizability of
    these analyses problematic.

  • Stanley Holmes

    This is valuable work from good scientists. They mentioned in their final discussion (only briefly) a clear limitation of their work that deserves more emphasis: we cannot know if what they are validating is the criteria for a medical disorder, or some dynamic time property of external social stressors that could be unrelated to any medical issue (as the authors are pointing, major stressors that can produce the same symptoms as MDD have a life of their own that can invalidate any work based on recurrence if you don’t try to control for them explicitly).

    I guess that even if stressors were in fact invalidating some of the conclusions, that work would still bring useful knowledge about prognosis the likeliness of external stressing social situations getting a life of their own and becoming recurrent based on the medical symptoms they cause (giving an insight about how to prioritize social work).

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  • Daniel

    As I psychiatrist, I don’t think that I have ever met a patient whom I would consider to have “a major depressive episode” who would actually meet criteria for “uncomplicated depression”

    • http://blogs.discovermagazine.com/neuroskeptic/ Neuroskeptic

      I’d be surprised if you had – such people probably often don’t seek treatment, or if they did, it would be dealt with in primary care. The point (as I see it) is that some substantial % of people who meet DSM criteria for an MDE actually don’t need treatment & will recover fine without it, with no sequelae. Of course there are others with an MDE who are more severely ill & those are the ones psychiatrists see.

  • Rap_Porter

    While there is a lot of controversy regarding “pathologizing” natural reactions to loss, unfortunately, in the U.S. one usually must have a diagnosable condition in order to get treatment covered by insurance. In addition, research shows that depression due to bereavement is very similar to, and responds to the same treatments as, depression from many other causes that have long been accepted in the DSM, as I learned in the DSM-5 Pre-Publication Overview online course offered by psyte-online.com (http://psyte-online.com/online-courses.html).

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  • trreddy

    Its true,i agree with Daniel about uncomplicated Depression.

  • sabiha ahmad

    my father is 77 year old…he lost his wife 7 years back.then he was diagnosed with fistula which was cured later he was diagnosed with prostrate cancer again he was cured, the cancer is 100% clear now but now he is always complaining of bad health and this has become his habit…recently we have noticed he is not ready to leave his bed..he is always talking about illness (his own), medicines and doctors.kindly guide what is he suffering froma nd how he can be cured?

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  • Linda Roberts

    probably all of us have at least once had depression complicated or not it does not matter its still unpleasant. i had such an experience and it was the worst time of my life. totally isolated from outer life. many of us however think that depression is a mental or emotional problem but in reality these are not the only reasons. for instance the deficiency of some elements vitamins and fatty acids can cause depression.

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About Neuroskeptic

Neuroskeptic is a British neuroscientist who takes a skeptical look at his own field, and beyond. His blog offers a look at the latest developments in neuroscience, psychiatry and psychology through a critical lens.

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