The main feature of hoarding disorder is a person’s irrational, persistent difficulty in discarding or parting with possessions — regardless of their actual value. This is a long-standing difficulty, not just something related to a one-time circumstance (such as having difficulty discarding property from something you inherited from a loved one).Discarding means that the person can’t seem to give away, throw away, recycle, or sell things they no longer need (or sometimes, even want).
There are many reasons people give for not wanting to discard or part with things in hoarding disorder. Some feel they are just being frugal and don’t want to be wasteful. Others have a sentimental attachment to their things, regardless of whether there is any actual history or sentiment that ordinarily one might have (such as a collection of old newspapers or magazines). Still others fear there is “important information” in the things that could be discarded, and they just need to “go through” them all to ensure that information is removed.
More on this @ PsychCentral.com