Pain: Physical and Psychological

Scott Alexander has a long review of a book that argues most chronic pain is psychosomatic. He also looks at lots of study results on the psychological and physical factors that might be causing chronic pain. To get an idea of how complex and controversial this is, consider the summations of two recent reviews that compared published studies to find out whether poor mental health causes or worsens back pain. Study 1 says:

The available literature indicated a clear link between psychological variables and neck and back pain. The prospective studies indicated that psychological variables were related to the onset of pain, and to acute, subacute, and chronic pain. Stress, distress, or anxiety as well as mood and emotions, cognitive functioning, and pain behavior all were found to be significant factors. Personality factors produced mixed results. Although the level of evidence was low, abuse also was found to be a potentially significant factor.

Study 2 says:

According to recent epidemiological literature we found moderate evidence for no positive association between perception of work, organisational aspects of work, and social support at work and LBP [lower back pain]. We found insufficient evidence for an association between stress at work and LBP. Regarding consequences of LBP, there was insufficient evidence for an association between perception of work in relation to consequences of LBP. There was strong evidence for no association between organisational aspects of work and moderate evidence for no association between social support at work and stress at work and consequences of LBP. There were major methodological problems in the majority of studies included in this review and the diversity in methods was considerable. Therefore associations reported may be spurious and should be interpreted with caution.

Clear, right?

Right now the data seem to argue that physical causes of some sort are highly relevant for most pain. That doesn't mean psychological factors are irrelevant, just that you are unlikely to suffer serious chronic pain from psychological factors alone. Your mental state absolutely will effect how well you cope with pain, e.g., whether you are able to keep working. But we are very far from understanding how any of this works, and what causes chronic pain in the first place.

If you're curious, read Alexander.