Nov. 16, 1999 (New York) -- According to the findings of a recent study, women with fibromyalgia may have malfunctions in two key systems -- the autonomic ("automatic" or self-controlling) nervous system and the HPA axis, which regulates production of certain hormones and the body?s response to stress.
Boston researchers discovered that the HPA axis -- a complex brain-to-body pathway involving the hypothalamus and the pituitary and adrenal glands -- is damaged. As a result, it does not properly regulate production of cortisol, a hormone with widespread effects throughout the body.
"Impairment of these neuroendocrine systems may explain the [underlying body-system malfunctions] of fibromyalgia as well as the overlap in signs and symptoms between fibromyalgia and related disorders," write Gail K. Adler, MD, PhD, and fellow Harvard Medical School researchers. The study was conducted at Brigham & Women's Hospital, affiliated with Harvard, and published in a recent issue of the American Journal of Medicine.
A chronic disorder, fibromyalgia is characterized in part by extreme fatigue, widespread musculoskeletal pain, multiple tender body points, and sleep disturbances. It affects an estimated 3 to 6 million Americans, primarily women of childbearing age.
The existence of fibromyalgia as a distinct disorder has sparked a great deal of controversy over the past decade. This is due in part to a lack of traditional scientific standards to define or explain fibromyalgia and other poorly understood, often-overlapping conditions such as chronic fatigue syndrome, irritable bowel syndrome, depression, and migraine.
Some studies have suggested that women with fibromyalgia have decreased function of the HPA axis, while others have found that there may be an excess of activity in the same system. In both cases, levels of key hormones are affected, in turn resulting in the symptoms of fibromyalgia.
The HPA axis and the autonomic nervous system are the major pathways for body responses to stressful conditions -- for example, pain, low blood sugar, low blood pressure, exercise, trauma, and infection. Both systems also are influenced by genetic and environmental factors and by chronic illness. "Furthermore, factors associated with fibromyalgia, such as medication use or changes in physical activity, could influence these systems," Adler and colleagues write. "However, because [affected hormones] ? and the autonomic nervous system influence pain, alertness, gastrointestinal motility, fatigue, ? blood pressure, and immune function, dysfunction of either of these systems might contribute," they say, to the start of fibromyalgia or its persistence.