Pfizer and Eli Lilly are promoting drugs to treat fibromyalgia, an ailment characterized by pain, fatigue and depression. But some doctors say the marketing buzz is drowning out important questions about the condition, including:

WHAT'S THE CAUSE? There is still no agreement on what causes fibromyalgia, though some scientists point to abnormalities in the nervous system.

WHERE'S THE TEST? Unlike other pain conditions, such as arthritis, there is no medical test for fibromyalgia. Instead, doctors make a diagnosis by examining patients and listening to descriptions of symptoms.

WHAT'S UNIQUE? A quarter of patients diagnosed also fit the criteria of other disorders, raising questions about whether fibromyalgia is a unique disease.

MIND OVER MATTER? Patients diagnosed with fibromyalgia are more likely to have a history of mental illness, be overweight and economically disadvantaged. Some doctors say their suffering may stem from difficult circumstances rather than disease.