When physicians see patients with medically unexplained fatigue, they often infer that this illness is due to an underlying psychiatric problem. The Authors
Ronald Reagan said to Gorbachev, “Take down that wall!” and it did ultimately fall. The ME/CFS version of that might be, “Get rid of those stubborn psychiatric ideas!” It’s a cultural problem. The authors pointed out that anytime a physician sees a patient with unexplained fatigue, their default diagnosis is likely to be a psychiatric illness.
This study will probably bring them little joy. Three longtime ME/CFS researchers have just produced another nail in the coffin of a psychiatric interpretation of ME/CFS.
Gudrun Lange, a clinical neuropsychologist, and Benjamin Natelson (the first author), a neurologist, have worked and collaborated together on everything in ME/CFS from brain imaging to exercise to cognition for over two decades. Elizabeth Unger, the head of the ME/CFS research effort at the CDC, was the senior author on the study.
This may be a hard, hard study for anyone to refute. It was fairly large (n=63) and the study protocol – which involved consecutively enrolling patients seen at Dr. Natelson’s practice – defied any possibility of cherry-picking.
The authors used the 1994 Fukuda definition because of its more stringent exclusionary criteria (schizophrenia, bipolar disorder, melancholic depression, eating disorder within 5 years, or drug/alcohol abuse within 2 years). (While the Canadian Consensus Criteria (CCC) or International Consensus Criteria (ICC) identify a sicker and more functionally impaired group of patients, it’s possible their longer list of symptom criteria may also pluck out patients with more psychiatric diagnoses.)
Benjamin H Natelson, Jin-Mann S Lin, Gudrun Lange, Sarah Khan, AaronStegner & Elizabeth R Unger (2019): The Effect of Comorbid Medical and Psychiatric Diagnoses on Chronic Fatigue Syndrome, Annals of Medicine, DOI: 10.1080/07853890.2019.1683601
The study design was fairly simple. First, the researchers assessed the presence of comorbid diseases (fibromyalgia, irritable bowel syndrome (IBS), multiple chemical sensitivity (MCS)) and psychiatric diagnoses (present and those at least five years in the past).
The participants then filled out a long list of questionnaires which provided data on their symptoms. (The questionnaires included fatigue, symptom, functionality and mood disorder questionnaires (Short Form Health Survey (SF-36v2); Multidimensional Fatigue Inventory (MFI-20); the PROMIS measures (Pain Intensity and Pain Behavior); the CDC Symptom Inventory (CDC-SI); the Zung self-rating depression scale; and the Patient Health Questionnaire depression scale (PHQ-8).
The researchers then assessed the effect that having a comorbid illness or a mood disorder had on the ME/CFS patients’ symptoms, functionality, etc. The idea was that having any disorder which played a role in causing ME/CFS or was closely linked to ME/CFS should make the participants’ ME/CFS symptoms worse. A disorder, on the other hand, which didn’t play a role in causing ME/CFS or was not closely linked to it might make some symptoms worse but wouldn’t make the participants’ ME/CFS symptoms worse.
Mood disorders were indeed commonly found: 36% of the participants had a current psychiatric diagnosis, 32% had a past psychiatric diagnosis and 32% never had a psychiatric diagnosis.
Having a psychiatric diagnosis – either past or present – though, made no difference at all with regard to several major areas. Having a mood disorder was not associated with an increase in the number of co-morbid disorders (FM, IBS, MCS) one had. Nor was it associated with increased symptom severity, longer illnesses, more medications, onset type, disability, or importantly, the severity of the key symptom in ME/CFS – post-exertional malaise.
Having a mood disorder was associated with significantly increased scores on the depression tests, mental health as well as mental fatigue.
ME/CFS is NOT a Somatization Disorder (or Who’s the Deluded One Now?)
The first implication to draw from this study is that ME/CFS is not a somatization disorder. Somatization disorders occur when a person believes that what are, in fact, psychiatric symptoms have a physical cause (and goes doctor shopping.)
Given that interpretation, it’s not surprising that the idiopathic or medically unexplained symptoms in ME/CFS have led to a rather rich history of psychiatrists attempting to define ME/CFS as a somatization disorder. The increased rates of depression found in ME/CFS have many times been cited as a reason to regard ME/CFS as one.
Back in 1991, a large study published in the American Medical Journal, which undoubtedly got a lot of attention, asserted that ME/CFS was a somatization disorder. In 1996, Natelson argued that few ME/CFS patients met the strict criteria for somatization disorder and showed that the interpretation one made of the symptoms in ME/CFS (physical vs psychiatric) played a critical role in the diagnosis.
In a very long 1997 review, “Chronic fatigue syndrome: a 20th century illness“, Simon Wessely put ME/CFS with other somatization disorders. A 2007 German study, co-authored by Trudy Chalder, suggested that ME/CFS substantially overlapped with somatization disorder.
Since then, Maes has several times argued for a biological cause to the seemingly “somatic” symptoms found in ME/CFS, and a 2019 study, which assessed “illusory mental health” (people who thought they were mentally well but were not), found no evidence of increased IMH in ME/CFS and concluded that ME/CFS is not a somatization disorder.
Since somatization is by definition a psychiatric disorder masquerading in the patients’ mind as a physical disorder, the presence of a mood disorder should magnify the patients’ symptoms greatly. Natelson et. al. pointed out that studies indicate that mood disorders are “illness multipliers” in somatization disorders; i.e. they make them worse.
But not in ME/CFS. Having a past or present mood disorder didn’t make any of the symptoms associated with ME/CFS worse. (It did, however, make the symptoms associated with mood disorders worse.) Since having a mood disorder didn’t increase any of the symptoms associated with ME/CFS, ME/CFS is, by definition, not a somatization disorder.
It goes deeper than that. The fact that having a mood disorder did not exacerbate the symptoms (fatigue, pain, post-exertional malaise, etc.) one associates with ME/CFS suggests the neurobiological causes of the two conditions must be different. That may come as something of a surprise to researchers who assumed that at least the fatigue in the two diseases was probably being caused in a similar manner. This study suggests, though, that other than being an excellent way to cause depression, ME/CFS doesn’t share much in common with depression biologically.
In other words, ME/CFS, like many other chronic illnesses, will increase the risk of depression, but appears to be entirely separate from it.
We can add another item to a rather long list of ways to prove to your doctor that you’re not depressed.
The Real “Illness Multipliers”
Contrast that with what happened when the effects the comorbid illnesses (fibromyalgia, IBS, MCS) had on the symptom picture in ME/CFS were assessed. Only 18% of Natelson’s group did not have at least one other comorbid illness.
Having a comorbid illness significantly increased issues with physical functioning, body pain, symptom severity, symptom quantity, pain intensity, pain behavior and the ability to work. The symptom multiplier effect that occurred when two (or more) illnesses occurred together suggests some sort of biological synergy or some common biological pathways are affected in all these diseases.
Hopefully, similar studies will be done on FM and IBS and other allied diseases where somatization interpretations remain. Just this May, a study concluded that IBS is associated with increased symptoms and pain, somatization, depression, fibromyalgia, (and altered dietary fluids composition).
Even in FM, where the central sensitization findings can easily explain the increased pain in FM, a 2013 review asserted that FM can be classified as any number of psychological disorders including functional syndrome, somatoform pain disorder and somatization disorder. In 2017, defying all the biological research to date, German researchers argued that FM should be classified as a “somatic symptom disorder” (SSD); i.e. a mental disorder.
A Primary Care Doctor Poll
My experiences with my last two primary care doctors have been good. While neither knew much about ME/CFS or FM, both acknowledged that they were real, biological disorders. Both appeared to take them seriously. One was open to trying out some tests recommended by my ME/CFS expert. (I haven’t asked that of the other one yet.)
The Primary Care Doctor poll seeks to learn what your recent experience with your primary care doctor (not your specialist) has been. If you’ve seen your primary care doctor for ME/CFS in the past five years, please take the poll.
This study asked what effect having a comorbid disease or a mood disorder had on the symptoms a person with ME/CFS experiences. If having another disease increased a person’s ME/CFS symptoms, then that disease was assumed to be biologically connected in some way with ME/CFS. If it didn’t increase the symptoms associated with ME/CFS, then that disease was assumed not to be biologically connected to ME/CFS.
The study suggested that diseases such as FM, IBS and MCS are, in some way, biologically associated with ME/CFS: having one of them in addition to ME/CFS exacerbated the key ME/CFS symptoms (e.g. fatigue, pain, PEM, etc.) found in ME/CFS.
Mood disorders, on the other hand, do not appear to be closely biologically associated with ME/CFS: having a mood disorder in addition to ME/CFS only increased the symptoms associated with having a mood disorder – not the core symptoms of ME/CFS.
Contrary to attempts to label ME/CFS as a somaticization or other kind of psychiatric disorder over the years, it appears to have little in common with either. That suggests that the higher levels of mood disorders found in ME/CFS most likely simply reflect the difficulty associated with having an illness.
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