Compulsive shopping -- an overwhelming preoccupation with purchasing unneeded items -- sounds more 
like a running sitcom joke than a legitimate disorder, but the problem is real. As many as twenty million Americans may be compulsive shoppers; like gamblers, their habits damage relationships, break up families and send them into debt.
I don't consider myself a compulsive shopper. (I mean, who hasn't spent six straight hours looking at flat-weave Persian rugs on eBay every now and then?) But like many people, I'm not above a bit of retail therapy, and like many people I've learned that a deep, sudden desire to Buy More Stuff is a response -- a profoundly unfulfilling response -- to periods of stress and dissatisfaction.
Such periods are not simply moods, but the products of frustrated desires, looming concerns, struggling relationships -- in short, life. This is, of course, only my own experience, and can't be scientifically extrapolated, but I wasn't surprised to read this:
The lead investigator said the results were a "shock" and could perhapsbe explained by a more complex biological explanation for the disorder.
But I think the roots of compulsive shopping go far deeper than merepersonal biology.
Study Of Drug Therapy For Compulsive Buying Yields A Puzzle [press release]