Chronic Fatigue Syndrome Is Not Depression

Many peo­ple go to the doc­tor because they feel tired all the time. Many of these patients are suf­fer­ing from major depres­sion. These depressed patients often feel bet­ter if they get more exer­cise. How­ev­er, some patients feel tired because they are tee­ter­ing on the edge of phys­i­cal col­lapse because of some seri­ous cir­cu­la­to­ry, meta­bol­ic, or neu­ro­log­ic dis­or­der. If these seri­ous­ly ill peo­ple try to exer­cise more, they may end up in big trou­ble. So it is impor­tant for doc­tors to make the cor­rect diag­no­sis in these cas­es. Oth­er­wise, the doc­tor may offer advice that does more harm than good.

Accord­ing to the dic­tio­nary, fatigue is extreme tired­ness, typ­i­cal­ly result­ing from men­tal or phys­i­cal exer­tion or ill­ness. In oth­er words, fatigue is nature’s way of telling you to rest. How­ev­er, a per­son may feel fatigue for many dif­fer­ent rea­sons. As psy­chol­o­gist Doug Lisle explained in his book The Plea­sure Trap, all ani­mals must bal­ance three con­flict­ing moti­va­tions: to feel plea­sure, to avoid pain, and to con­serve ener­gy. So besides decid­ing whether an activ­i­ty is plea­sur­able or painful, ani­mals must also pre­dict whether a plea­sure is worth the ener­gy they would have to expend to obtain it, and whether a pain would be so bad that the effort to avoid the pain would be worth­while. This esti­ma­tion that some effort would be either unpro­duc­tive or dan­ger­ous can pro­duce a sen­sa­tion that is felt as fatigue.

Depres­sion involves a prob­lem with the brain’s abil­i­ty to pre­dict and feel plea­sure. For this rea­son, the depressed person’s brain con­cludes that many kinds of phys­i­cal and men­tal efforts would not be worth­while. As a result, depressed peo­ple often feel fatigue, even if they are nowhere near their phys­i­cal lim­its. (In con­trast, peo­ple with mania often run them­selves into a state of phys­i­cal exhaus­tion.) When non­de­pressed peo­ple are approach­ing their phys­i­cal lim­its, their brain warns them that fur­ther effort would be dan­ger­ous. This warn­ing is also felt as fatigue, even if the person’s activ­i­ty lev­el is abnor­mal­ly low. Peo­ple who push them­selves despite this warn­ing can make them­selves much sick­er. This result is called post-exer­tion­al malaise, or the push-crash phe­nom­e­non. Peo­ple who are this sick have a low health-relat­ed qual­i­ty of life. As a result, they may look and feel depressed, which com­pli­cates the diag­no­sis.

Do not assume that some­one can exer­cise his or her way out of a case of a chron­ic fatigu­ing ill­ness. Many of these peo­ple have an under­ly­ing dis­or­der that must be found and cor­rect­ed. In the mean­time, the peo­ple may have to avoid exer­cise, so that they can use their lim­it­ed sup­ply of ener­gy to do the things that are most impor­tant to them.

Many of the prob­lems that cause dis­abling fatigue fall into two basic, over­lap­ping cat­e­gories: prob­lems with ener­gy metab­o­lism (cel­lu­lar res­pi­ra­tion) and prob­lems with stand­ing or sit­ting up (orthosta­sis).

Many dif­fer­ent kinds of prob­lems can inter­fere with cel­lu­lar res­pi­ra­tion. Lung dis­eases can lim­it the flow of oxy­gen into the blood­stream. Ane­mia lim­its the blood’s abil­i­ty to pick up the oxy­gen and car­ry it to tis­sue. Cir­cu­la­to­ry dis­ease lim­its the body’s abil­i­ty to deliv­er oxy­genat­ed blood to tis­sue. Nutri­tion­al defi­cien­cies or dam­age to the cells’ mito­chon­dria can inter­fere with the body’s abil­i­ty to use oxy­gen to burn fuel to release ener­gy.

In oth­er words, chron­ic fatigue can result from a wide vari­ety of seri­ous dis­eases, many of which are so rare that doc­tors do not rou­tine­ly test for them or even know about them. Each of these rare dis­eases affects only a few peo­ple. Yet togeth­er, these rare but seri­ous fatigu­ing ill­ness­es could account for a large num­ber of peo­ple, most of whose ill­ness­es nev­er get a prop­er diag­no­sis.

Some of these rare prob­lems can be caught if the doc­tor lis­tens and looks: takes a care­ful his­to­ry and does a care­ful phys­i­cal exam­i­na­tion. For exam­ple, to catch cas­es of spinal flu­id leak, doc­tors must look for patients who have a con­nec­tive tis­sue dis­or­der (abnor­mal­ly tall or abnor­mal­ly flex­i­ble) or a his­to­ry of spinal injury/surgery or lum­bar punc­ture. They must also lis­ten to the patient’s com­plaints. Patients with a spinal flu­id leak will typ­i­cal­ly say that they feel bet­ter in the morn­ing or after pro­longed bed rest but worse in the after­noon or evening or after pro­longed sit­ting or stand­ing. An ordi­nary MRI might not reveal the leak. Instead, the patient may need mag­net­ic res­o­nance myel­og­ra­phy. Yet if the leak is found and patched, the patient can get well.

Low blood vol­ume (hypo­v­olemia) can eas­i­ly be mis­tak­en for an anx­i­ety dis­or­der. These patients are pale because of poor cir­cu­la­tion. The extra nor­ep­i­neph­rine that their adren­al glands release to com­pen­sate for the short­age of blood can cause tremor and mood dis­tur­bance. Their pulse tends to be rapid and weak. In addi­tion to fatigue, hypo­v­olemic patients may com­plain of dizzi­ness or faint­ing and an inabil­i­ty to see when they stand up. Yet the results of their com­plete blood count may be per­fect­ly nor­mal. How­ev­er, the com­plete blood count only tells you whether the blood is good. It does not tell you how much blood the patient has. To test for low blood vol­ume, start with a poor-man’s tilt table test: take the pulse and pres­sure while the patient is lying down, sit­ting, and then stand­ing. If the pulse goes up a lot or the pulse pres­sure (sys­tolic minus dias­tolic pres­sure) goes down while the patient is stand­ing, the patient prob­a­bly has low blood vol­ume.

Remem­ber that many vague symp­toms, includ­ing fatigue, can result from food aller­gy or intol­er­ances. Doc­tors can solve many of these prob­lems just by giv­ing the patient a sim­ple hand­out with instruc­tions on how to fol­low an elim­i­na­tion diet.

Many patients who are on the edge of phys­i­cal col­lapse are mis­tak­en­ly thought to be suf­fer­ing from a pri­mar­i­ly psy­chi­atric prob­lem. Yet if the patient is on the edge of phys­i­cal col­lapse, mis­guid­ed psy­chother­a­py and the pres­sure to exer­cise can do a great deal of harm. If the under­ly­ing phys­i­cal prob­lem can­not be resolved, the patient needs cop­ing skills for liv­ing with the dis­abil­i­ty, as well as help in get­ting oth­ers to under­stand and accept his or her lev­el of dis­abil­i­ty.

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