What are the symptoms of depression?

No two people are likely to experience the same exact symptoms in their depression.  Both frequency and length of time of symptoms will be different for most individuals. 

Symptoms of depression include:

Loss of appetite or over-eating
fatigue
hopeless and persistent negativity
Feelings of guilt and worthlessness
Suicidal thoughts or attempts
Chronic pain
Digestive problems
Early morning insomnia or over-sleeping
Sadness combined with anxiety
Irritability
Cognitive difficulties and poor concentration
Low motivation and lack of interest in physical intamacy or hobbies

Depression can co-occur with other disorders, including anxiety, Post Traumatic Stress Disorder (PTSD), and substance abuse.  People with PTSD are very much at risk for depression as well as anxiety, as they often find themselves reliving their trauma.

According to the NIMH, depression is the result of "genetic, biochemical, environmental, and psychological factors."  While research has shown through MRIs that the brains of depressed people look different than non-depressed people, the cause remains somewhat of a mystery.  Because depression appears to be connected to the above mentioned factors, psychotherapy is considered to be a valuable part of the treatment for this disorder, as a good therapist can help to draw the connections between genetics, environment, and psychological factors.