The American Pain Society issued the following news release:

PTSD Influences Levels Of Depression And Pain
22 Jul 2008

Patients with accident or trauma related chronic pain often have post-
traumatic stress disorder (PTSD) and depression. What isn’t clearly
known, however, is how PTSD relates to mood disorders and pain severity
in chronic pain patients.

University of Michigan researchers examined the contribution of PTSD to
the pain experience, functional disability and frequency of depressive
symptoms. They studied 241 patients referred to the university
hospital’s pain rehabilitation program who reported their pain began
after a traumatic injury. The subjects completed the McGill Pain
Questionnaire and were administered the Pain Disability Index and the
Post-traumatic Chronic Pain Test.

Results showed PTSD and depression are significantly correlated and both
disorders are associated with perceived disability attributed to chronic
pain. Therefore, in cases of disabling accident-related chronic pain
with comorbid depression, symptoms of PTSD may be critical to
understanding both disorders.

The authors concluded that increased attention to treating PTSD as a
primary focus in the rehabilitation of patients with chronic pain and
comorbid depression is important when prior treatment efforts for pain
and depression have not been successful.