Everyone occasionally has bouts of sadness, but these feelings are usually temporary. When a person has a depressive disorder, it interferes with daily life and normal functioning. It is a common but serious illness. There is no single cause of depression, but it likely results from a mix of genetic, biochemical, environmental and psychological factors. Depression commonly coexists with other illnesses, such as anxiety disorders or substance abuse. It can affect anyone at any time, including children. Read More