13Patients with chronic pain often describe depressive symptoms which are rarely severe enough to be regarded as a depressive illness, although the latter should not be totally disregarded. The key feature of depression is having a negative view of oneself, the environment and the future. Patients may have a lack of energy and interest in life with a slowing up of mental function. They may feel sad, hopeless and demonstrate a pessimistic view of their future. Sleep, appetite and sex drive may be affected and many describe unexplained problems such as aches and pains, headaches, weakness and constipation.

For most patients, depressed mood is thought to be a consequence of their pain and the best treatment is helping them regain some measure of control over their pain and disability. Again, depressive thoughts will increase hopelessness, catastrophising about pain, fear and the physical pain experienced.