Collecting is a hobby that for many people is a fulfilling pastime. It may seem harmless at first, but when collection turns into clutter, it can be labeled as hoarding disorder.

Hoarding, the compulsion to hold onto items that have no value, was once considered to be an obsessive compulsive disorder (OCD). The fifth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) now puts hoarding in a class of its own.

Hoarding disorder and collecting are differentiated by the value of items that make up a collection. Items that hold value are included in what would be considered as a normal collection.  A hoarder is someone who accumulates items that have no value and would be considered junk, in an objective sense.

"A collector, in theory, will sell or cull a collection when they don't have enough room for all the objects. A hoarder will just fill the room, literally fill the room to the brim," clinical psychologist and co-author of the psychology textbook, "Abnormal Psychology", Robin Rosenberg said.

Shows like Hoarders, A&E's documentary series shows how obsessively accumulating material things can become hazardous. Intervention efforts include having the hoarders work with psychologists and professional organizers to resolve their obsessive habit of collecting.

"It is often a little bit made fun of in films, but as an actual disorder it is not funny. People can be really crippled by their inability to throw things away and it is a safety hazard," Rosenberg said.

As Live Science reported, research finds that hoarders and people with OCD have a different pattern of symptoms. Someone who checks locks repeatedly to be sure that they are locked in as an example of an OCD. Brain imaging studies also indicate that the neurobiology of hoarding disorder is different from OCD.

The American Psychiatric Association task forces behind the changes in DSM-5 argue that according to data, hoarding is not an OCD symptom.