and Overlapping Disorders: Variations on a
By Katrina Berne, PhD
Many chronic disorders
share common features, including symptoms and abnormalities. Studies of
illnesses such as chronic fatigue and immune dysfunction syndrome (CFIDS),
fibromyalgia (FM) and irritable bowel syndrome (IBS) show that several chronic
disorders often occur in the same patient. Since these illnesses are
compartmentalized and labeled, each is studied as a discrete disorder. But as
common factors become more apparent, the boundaries between illnesses tend to
Because of the number
of overlapping symptoms and characteristics, there is speculation that many
chronic conditions are either related or are different manifestations of the
same illness, perhaps caused by similar factors. Muhammad Yunus, MD, considers
CFIDS, FM, Gulf war illness, multiple chemical sensitivity disorder and others
to be part of a greater grouping that he calls “central sensitivity syndrome,”
A group of overlapping
disorders is presented below. Numerous others have been excluded due to space
constraints. The illnesses profiled here overlap in terms of symptoms;
complexity; poorly understood pathophysiology; variability among cases;
increased prevalence in women; possible involvement of infectious agents;
dysfunction of the immune and central nervous systems; known or suspected
autoimmune component; and dismissal or lack of “real” illness status unless a
marker or test has been identified.
Their relationships to
one another remain unclear. Similarities of symptoms and multiple dysregulations
suggest a common mechanism in several conditions, possibly
hypothalamic-pituitary-adrenal (HPA) axis dysfunction. The HPA axis controls the
release of hormones in response to stressors; in CFIDS, the axis may be
disrupted because of abnormalities in the central nervous and immune systems.
The mechanisms of the HPA axis are complex and delicate, and minor variations in
dysfunction might account for similarities among these disorders.
About 75 percent of people diagnosed
with CFIDS meet the criteria for FM. Fifty-eight percent of females with FM, and
80 percent of males with FM, meet CFIDS criteria. Symptoms of both illnesses
include pain, gastrointestinal problems, cognitive difficulties, sleep
disturbance and neurological problems such as lightheadedness, fainting and
People with both
conditions typically show normal results on routine lab tests. Both illnesses
are most common in women in their middle years. Strenuous activity can trigger
relapses, the illnesses wax and wane and secondary psychological problems such
as depression, anxiety and mood swings are common for people with both
There are also a number
of physiological similarities. For instance, abnormalities in the central
nervous system, such as low levels of brain transmitters serotonin and
norepinephrine, are common to both illnesses. Immune system abnormalities are
often similar, and include decreased function of natural killer cells, increased
antibody (cytokine) levels and disturbances in hormone secretion and
Differences between two
conditions have been noted. Fatigue is more common in CFIDS, while people with
FM have tender points and “trigger” points that cause pain. Substance P, a brain
chemical associated with pain signal transmission, is elevated in FM but more
often normal in CFIDS. And abnormal versions of the blood-based protein RNaseL
are common in CFIDS but much less prevalent in FM cases.
community cannot yet give us a definitive answer to the question of the
relationship between CFS and FM for many reasons. Diagnostic criteria vary among
studies, making it difficult to compare results. No objective tests exist to
measure such symptoms as fatigue. And large-scale comparative studies have not
Whether it is the same
illness, subtypes of one illness, or different illnesses, the bottom line is the
same: More funding and larger, better-designed studies are needed.
Bowel Disease (IBD) and
Gastrointestinal symptoms are common in people with CFIDS and FM. IBD
is a serious, chronic condition, often accompanied by arthritis-like pain and
occurring in a waxing-and-waning pattern that significantly impacts one’s
lifestyle. Two serious types of IBD are Crohn’s disease, a severe inflammation
of a part of the gastrointestinal (GI) tract, and ulcerative colitis, an
inflammatory process of the large intestine. Crohn’s is characterized by
abdominal pain, diarrhea, fever and weight loss, sometimes with serious
complications. Symptoms of ulcerative colitis include abdominal cramps, blood
and mucus in the stool and increased urgency to defecate. Attacks may be severe
and sudden, with the possibility of severe complications.
IBS is more common than
IBD in people with CFIDS. It is a function of bowel function rather than
structure, and is estimated to affect 20 percent of adults in the Western world.
A distressing disorder that greatly affects one’s quality of life, IBS was once
dismissed as a mild, psychogenic disorder of gut motility. It is now regarded as
the result of brain-gut dysfunction with dysregulation of the autonomic nervous
system. This autonomic dysfunction may account for the presence of IBS in both
CFIDS and FM.
The U.S. government has alternately acknowledged and denied the
existence of a group of symptoms experienced by at least 100,000 of the 700,000
U.S. troops deployed to the Persian Gulf in 1990. Although no case definition
for Gulf war illness (GWI) exists, its symptoms strongly resemble those of
CFIDS, FM and rheumatoid arthritis. More than half of GWI patients meet criteria
Symptoms occurring in
Gulf war veterans include debilitating fatigue, post-exertional fatigue,
widespread muscle and joint pain, sleep disorders, temperature dysregulation,
night sweats, headaches, numbness, swelling in joints and extremities,
irritability, depression, malaise and a number of neurological symptoms,
including cognitive impairment, blurred vision and balance problems. Many Gulf
war veterans have suffered long-term health problems, and their significant
others have become ill as well.
GWI patients often show
immune abnormalities similar to those in people with CFIDS. These include
overreaction of cytokines and T-cells; diminished numbers of, and unusual
changes in, natural killer cells; abnormal ratios of immune cells called CD4 and
CD8; and reactivation of Epstein-Barr virus and human herpesvirus 6
chemical sensitivity disorder (MCS), also known as environmental illness, is
characterized by immediate or delayed reactions to various environmental
chemicals. Toxins are everywhere in our environment. Offending chemicals are
found in food additives, drugs, perfumes and other scented products, pesticides,
herbicides and room deodorizers, natural gas, tobacco smoke, solvents, carpets
and household furnishings. When these chemicals are inhaled, eaten or drunk,
they are able to cross the blood-brain barrier, causing neurological damage.
Various studies suggest
that MCS is present in 40-80 percent of people with CFIDS, and the majority of
people with a primary diagnosis of MCS have concurrent CFIDS, FM, GWI and
allergies. Although there is no specific test for MCS, abnormalities have been
detected on immune and brain imaging tests.
Symptoms of MCS can
span multiple organ systems. These symptoms include dizziness, headache or
migraine, nausea and other neurological sensations, breathing difficulty,
impaired concentration and memory, balance difficulties, musculoskeletal and
abdominal pain, irritability, depression and anxiety.
Lyme disease is a multisystem
inflammatory disorder that may affect the skin, joints, heart, eyes and nervous
system. It is caused by the bite of a tick infected with the spirochete Borrelia
burgdorferi or related species. Lyme disease often begins with a telltale
bull’s-eye-shaped rash and joint and muscle pain, although many patients are
unaware of receiving a tick bite.
Antibiotic treatment is
most successful in the early stages. Some patients respond well to treatment,
others recover over a long period of time, and some fail to recover fully, with
a lingering post-infectious syndrome or development of other serious illnesses
such as Lyme arthritis.
Months to years after
the initial infection, later symptoms include arthritis pain and swelling, sleep
disorder, generalized achiness, stiffness, weakness, heart palpitations,
headache, fever, shortness of breath and many other physical and cognitive
problems. The possibility that Lyme disease is related to CFIDS has been
explored, with no clear consensus. Some physicians find that patients diagnosed
with CFIDS and FM actually have undiagnosed Lyme disease.
or overgrowth of cells
from the uterine lining into the abdominal cavity, is characterized by menstrual
pain, fatigue, bloating, heavy and/or irregular bleeding and bowel disturbances.
Some studies indicate a statistically significant overlap with CFIDS/FM, while
others do not. The two conditions may exist simultaneously but there is no known
causal relationship at this point.
Depression does not cause CFIDS and
not present in all cases; however, many patients are given a psychiatric
diagnosis such as depression when a physiological diagnosis is not apparent.
Overlapping symptoms, presence of depressed mood in some patients, lack of a
known cause or marker and simple ignorance causes confusion between CFIDS and
Depressive symptoms in
physically ill patients may be a result of immune activation and cytokine
secretion, in addition to a psychological reaction to illness-related distress
and incapacitation. Complex interactions among the immune system, the HPA axis
and other neurological factors affect stress levels, emotions and vulnerability
to illness. Illness, in turn, affects these body symptoms. Studies show that
immune activation may precede the development of depression, with increased
levels of certain cytokines.
This article was adapted from “Chronic Fatigue Syndrome, Fibromyalgia and
Other Invisible Illnesses: The Comprehensive Guide” (Hunter House, 2002).
Katrina Berne, PhD, is a licensed clinical psychologist who specializes
in the treatment of people with CFIDS, fibromyalgia and related disorders. She
has had CFIDS since 1985.
Many survivors of
paralytic and nonparalytic polio have developed symptoms years after the initial
infection, possibly caused by damage to neurons. Symptoms of postpolio syndrome
include new-onset chronic fatigue triggered or worsened by physical exertion and
emotional stress; joint and muscle pain; cold intolerance; sleep disorder;
cognitive impairment; headache; neck pain; muscle pain (myalgia); low-grade
fever and increased sleep.
Outbreaks of “abortive”
or “atypical” polio cases occurred in numerous locations. In the 1940s, an
illness dubbed the “summer grippe” was characterized by abrupt onset, duration
of less than a week and flu-like symptoms. These cases were typical of
nonparalytic polio, caused by a mild polio virus. None of the people with summer
grippe developed full-blown polio; apparently the mild polio virus conferred
immunity against it.
However, even mild
viruses may have damaged the central nervous system. “Potentially half of those
diagnosed today with [CFIDS] may have in fact had summer grippe or undiagnosed
nonparalytic polio as children in the years before the vaccine became
available,” reports Richard Bruno, MD.