A hoarder is not simply a pack rat. A pack rat gets rid of some "collectibles" when he or she runs out of room in the garage or basement. A hoarder simply moves the stuff into the bathtub.
Hoarding is a symptom of a mental illness, an anxiety disorder -- some experts say obsessive compulsive disorder, while others say it's a category unto itself. It's defined by three primary traits: the obsessive collection of objects that seem useless to almost everyone else, the inability to get rid of any of them and a resulting state of distress or peril.
Like most obsessive behaviors, hoarding starts small. Someone thinks that maybe the information in today's newspaper could be useful at some later date -- and tomorrow's newspaper and the next day's. Or she begins to wonder if she may have accidentally tossed something valuable in the trash can, and keeps that bag of trash just in case. And the next bag of trash. Maybe collecting books, or dogs, or records or mail, and living with them every day, so eases symptoms of anxiety that these things become indispensible -- sort of an extreme case of a favorite blanket or a grandmother's locket or the family photos on the wall.
A hoarder might be afraid to waste anything. Or he may be such a perfectionist that he simply can't start sorting through piles of useless things for fear he may not do it exactly right.
Hoarding can be an indicator of an intense sense of responsibility or fear of making a mistake.
Not everyone who has lots of dogs or stacks of books or piles of mail is a hoarder, of course. Lots of perfectly healthy people have cluttered homes. So what makes "collecting" a case of "hoarding"? There are some telltale signs that probably mean it's time to seek help …