Various data suggests that somewhere between 4 and 15 million people in the U.S. meet the full criteria for hoarding. The excessive collection of items with the inability to discard them is also defined by its harmful emotional, physical, social, and financial effects, as voyeuristic viewers of the popular A&E show "Hoarders" can attest.

The psychological condition has long been associated with obsessive-compulsive behavior, but its categorization has been vague ... until now.

In the revised, fifth edition of the American Psychiatric Association's Diagnostic and Statistical Manual of Mental Disorders (DSM-5), otherwise known as the psychology bible, "hoarding disorder" will be listed as a separate diagnosis, characterized by a "persistent difficulty discarding or parting with possessions, regardless of their actual value."

The revised diagnosis should "result in more people having access to treatment," says Randy Frost, a professor of psychology at Smith College who specializes in hoarding issues.

Long before reality TV turned the spotlight on the curious collecting compulsion, hoarding has been the object of some degree of fascination. The infamous hermit hoarders of Harlem, Homer and Langley Collyer, have been immortalized in print and film, along with the 140 tons of trash found in their home where they were found dead in 1947. Among their treasures were human organs pickled in jars, live cats, the chassis of an old Model T, tapestries, hundreds of yards of unused silks and other fabrics, clocks, fourteen pianos, a clavichord, countless other instruments, and a human skeleton, to name just a few of the items.

Likewise, the eccentric and reclusive mother-and-daughter team of Edith and Edith Beale, relatives of Jacqueline Kennedy Onassis, were given their measure of immortality in the 1975 documentary and later Broadway production, "Grey Gardens," named for their dilapidated and utterly filled-to-the-brim mansion in East Hampton, N.Y.

Sadly for bygone hoarders like the Collyers and Beales, the disorder is only now getting the recognition that will prove helpful to sufferers. Recent research has revealed abnormal brain activity in people with hoarding disorder. And both experts and hoarders hope and believe that the new DSM classification will help bring about better treatment. DSM codes are used for insurance reimbursements and research grants, which can only help as well.

Says Frost, "Right now, there are very few clinicians who know how to treat it. Once it shows up in DSM, there will be much more pressure on clinicians to train in how to treat this problem."

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