Patterns of comorbidity

There are 3 common patterns of syndrome comorbidity between ME, FM, and psychiatric conditions. The patterns can be identified by their temporal relationship.

Antecedent (comorbid) psychiatric condition. Patients can have antecedent depression or anxiety—the psychiatric symptoms predate the onset of physical symptoms, often by many years. In these cases, the psychiatric and physical conditions respond independently to treatment. The comorbid psychiatric condi-tions respond to the usual recommended psychiatric and psychological treatments.

Coincident psychiatric condition. Although rare, in some patients, such as Ben (Case 2), psychiatric symptoms develop concurrently with the onset of ME or FM. In these patients, the psychiatric condition seems to be a part of the physical symptom constellation and all the symptoms vary in parallel. For example, on a bad energy or pain day, mood or anxiety will always be worse. These patients are difficult to treat because the psychiatric conditions do not generally respond to common psychiatric treatments. The focus needs to be on improving physical health. This is best accomplished through symptom management.¹⁶ Improvement in psychiatric symptoms will be concurrent with physical improvement.

Grief/secondary depression/anxiety. The most common psychiatric/psychological symptoms in patients with ME and FM are feelings of grief and worry due to multiple life losses and uncertainty about the future. These symptoms develop after the onset of physical symptoms, often when the chronicity of and losses due to the conditions become clear. Grief and worry lessen with improved physical health. Psychological support and psychiatric treatments are indicated if symptoms are severe.

Clinical tips

TABLE 1

Canadian consensus criteria for myalgic encephalomyelitis

The pathognomonic symptom in ME is postexertional malaise lasting more than 24 hours. The additional symptoms outlined in Table 1 must also be present. Those who equate ME with “fatigue” and forget the importance of the other symptoms will risk misdiagnosis and mistreatment.

To make a diagnosis of FM, widespread pain plus the additional symptoms outlined in Table 2 must be present. Tender point examination remains a helpful tool.

TABLE 2

2010 American College of Rheumatology criteria for fibromyalgia

In the absence of comorbid depression, patients with ME or FM do not exhibit depressed mood, anhedonia, excessive guilt, or suicidal ideation (the core affective symptoms of MDD). Ask your patient: “Which activities do you enjoy when you have a better day?” Patients with ME or FM will have a long list of things they want to do, when able. Patients with depression generally will not feel anything would be worthwhile or enjoyable.

To make a diagnosis of generalized anxiety disorder, anxiety in several areas of life must be present most of the time and be interfering substantially with daily function. Ask your patient: “What worries would you have if your physical symptoms resolved?” Patients with ME or FM will report that they would have few worries, whereas patients with anxiety will continue to have a long list of worries.

Treatment of comorbid psychiatric disorders

Psychotherapy. Cognitive-behavioral therapy (CBT) is a mainstay of therapy for most types of depression and anxiety. It is also used in many chronic medical conditions as a means of guiding patients in evaluating the accuracy and functionality of their beliefs about their illness and their lives and helping them maximize coping strategies. Despite recent reports of the benefits of a particular brand of CBT in ME,¹⁷ it is not a cure for ME or FM any more than it is a cure for cancer, heart disease, or arthritis.¹⁸

However, respectfully administered psychotherapy may help restore self-confidence, resolve grief and worry, and improve a person’s ability to self-manage. Psychotherapy can be very helpful but does not directly treat the core physical symptoms of biomedical conditions.

Psychotropics. Several antidepressant trials have been carried out in patients with ME, and none has resulted in significant improvement of core symptoms even when mood improves.^19,20 No drug (of any class) has met criteria for approval for treatment of ME in any country, although many drugs are used off-label for symptomatic treatment. A fuller discussion of symptomatic treatment of ME is beyond the scope of this article, but interested readers are referred to the Box, “Clinical Resources,” that lists several of the commonly used strategies.

A recently published meta-analysis of the use of antidepressants for treatment of FM concludes that “the TCA amitriptyline and the SNRIs duloxetine and milnacipran are first-line options for the treatment of fibromyalgia patients.”²¹ Two drugs have been approved for treatment of FM in the US and Canada: the antidepressant duloxetine and the anticonvulsant pregabalin. The effects of duloxetine on pain and mood in FM are independent of each other.²² The effect on pain is thought to be due to the noradrenergic effects, since SSRIs have little benefit in pain disorders.