Imagine the way you felt the last time you had the flu. You were flattened, devoid of all energy. Staying upright to get dressed was more than you could handle. You slept – and slept – and slept – and still experienced none of the normal refreshment that a good night’s sleep provides. A fog descended on your mind and fuzzed up memory, destroyed drive and made your head ache. You could not concentrate on simple mental tasks like reading. Though you were doing nothing physical, your muscles ached. Then it all went away and you forgot about it.

But now imagine that it didn’t go away. The same misery persists and dramatically alters your life. You cannot work. You move from bed to couch and back to bed. You go to doctor after doctor and they find nothing wrong. Routine blood tests, X-ray and scan results are normal. Someone prescribes an antidepressant, confirming the suspicions of family, friends, and some doctors that your debilitating physical symptoms are “all in your head.” Eventually, you find your way to a doctor who makes a diagnosis. You have CFS which stands for chronic fatigue syndrome, and which, as of early 2015, has been renamed system exertion intolerance disease or, in our acronym-laden age, CFS/SEID.

A long history, with different names

CFS/SEID has probably been around for more than 200 years, making its appearance in the medical literature as “neurasthenia,” a term applied to patients who were lacking in physical, emotional and cognitive energy without any discernible disease to account for their malaise, without any improvement over time and without any progression that brought them to a worsened state. They were mostly ladies, whose frail constitutions prevented them from exerting themselves and who mysteriously took to their beds for weeks at a time.

The Yuppie flu

British doctors in the 1950s christened the symptom complex myalgic (painful muscles) encephalitis (inflammation of the brain), even though there was no evidence for inflammation to account for the headaches, difficulty concentrating and memory problems patients experienced. In the US in the 1980s, the syndrome was dubbed the Yuppie Flu because it seemed to follow viral infections like infectious mononucleosis and occurred in cities where young urban professionals (“yuppies”) congregated. When reported from other settings as well, the name was changed to chronic fatigue syndrome.

No apparent cause, but a real illness

Because no single infectious, hormonal or immunologic cause for CFS emerged from many attempts to identify its cause, because it was impossible to measure the subjective complaints constituting the syndrome, and because some improvements occurred when antidepressants were prescribed, CFS was, for decades, viewed as a psychological disorder. But this view became more and more untenable as it became clear that the illness hit people who had no history of depression or inability to cope with life. Many CFS patients continued to be very productive, learning how to manage their lives within the limitations of their fatigue and mental fog. Laura Hillenbrand, author of Seabiscuit and Unbroken is one outstanding example. Though no cause has yet been identified for the illness, the name change from chronic fatigue syndrome to systemic exertion intolerance disease signals that the illness is one rooted not in psychology but in an, as yet, unidentified physical cause.

Epidemiology and diagnostic criteria

It is estimated that there are about 1 million patients with CFS/ SEID in the US at any given time. There is no evidence that its incidence is increasing, but it is quite possible that some cases are hidden on among the legions of people who have been diagnosed only with depression. CFS/SEID is more common in women than in men. Sometimes it follows directly upon an acute flu-like illness, but at other times appears out of nowhere. The diagnostic criteria at this time include 6 months of unexplained, life-altering fatigue and orthostatic intolerance, which means the inability to stand for more than very short periods. Four of eight other symptoms are also required and these include disturbances in memory and concentration, persistent sore throat, tender lymph nodes, muscle pain, joint pain, headache, disturbed sleep patterns, and malaise following even minimal exertion. Additional symptoms may include increased sensitivity to tastes, odors, temperature and noise.

A relapsing illness

A small minority of CFS/SEID patients get completely better and never suffer a relapse. The majority suffer relapses for prolonged periods of time, perhaps the rest of their lives. Relapses are triggered by infections, surgery, temperature extremes and stressful events. Another minority are severely affected from the beginning of their illness and require support in the activities of daily living for the rest of their lives. Deterioration, though, is unusual and suggests the diagnosis of CFS is wrong and further attempts to find the correct diagnosis are indicated.

Problems in mitochondrial energy production?

While there is no identifiable single cause for CFS/SEID, poor energy production seems to be at the root of the many symptoms in this illness, which has focused some researchers’ attention on mitochondria – the powerhouses of all cells in the body. Mitochondria must continuously recycle the molecules they use to produce energy and there is some indication that this process is impaired in people with CFS/SEID. Perhaps this is why experience has taught many CFS/SEID patients to pace their lives, always allowing significant time for recovery from exertion.

Boosting energy production

In addition to pacing life to allow recovery time, lifestyle alterations that seem to help CFS/SEID patients minimize relapses also happen to be useful in maximizing mitochondrial function. These include avoidance of drugs and environmental toxins, avoidance of processed foods with high carbohydrate and sugar concentrations, addition of whole foods containing plenty of antioxidants and high quality protein, correction of hormonal problems, especially of the thyroid gland, and decreasing chronic inflammation associated with obesity and allergies. Gradual and graded programs of exercise, outdoors with some sun exposure help prevent the loss of muscle associated with inactivity and improve Vitamin D levels, with positive effects on immune function. Continued research will most likely show that CFS/SEID has many causes, all of which result in impaired mitochondrial function.