It's official: Morgellons disease isn't caused by an infectious agent, federal researchers say.

A long-awaited study, released Wednesday by the journal PLoS ONE, may be a disappointment for those who have called for more awareness and recognition of Morgellons -- in which sufferers complain of crawling, itching feelings and of tiny specks and filaments sticking out of sores on their skin.

Researchers from the U.S. Centers for Disease Control and Prevention found that, of patients studied, 59% had cognitive deficits of some sort, and 63% had evidence of "clinically significant somatic complaints."

Those strange colored filaments and specks? Mostly just bits of cotton and nylon fibers from clothing, the authors concluded. They could have gotten stuck in the sores in relation to the constant scratching of the skin.

The researchers can't say what exactly causes Morgellons, but the results do fall in line with an Archives of Dermatology study described last year in a Times article, in which findings by Mayo Clinic researchers indicated that Morgellons disease might be better described by a psychological disorder known as "delusional parasitosis."

Not that this will necessarily deter people who believe they have a physical infection of some sort, The Times' article on last year's research goes on to show. And the disease has been vouched for by big names too -- including Joni Mitchell, who told The Times that she suffers from Morgellons as well.