By Renée Grinnell

A pronounced state of indifference or lack of interest.

 Can have many possible causes, including brain trauma or disorders, certain medications, heavy drug use, or witnessing a horrific event.

Example: A prisoner condemned to death sits passively in his cell, ignoring his meal and several unopened letters.

    Last reviewed: By John M. Grohol, Psy.D. on 1 Oct 2008