Upon examining several “psychosomatic” conditions, noting their hypothesized causes, observable signs (and lack thereof), and suffering through some of them myself over the years from time to time (as someone prone to somatization disorder but self-aware enough to recognize it for what it is), I’ve come to the conclusion that these disorders are largely neurological rather than psychiatric in origin. That’s not to say that stress or other psychiatric factors can’t provoke these diseases; they very often do. However, the predisposition to these conditions appears to be largely innate, with lower pain thresholds and increased visceral sensitivity prevalent in a number of conditions, as well as objectively observed differences in the levels and balance of neurotransmitters (particularly serotonin). And then there’s the resistance of somatization to psychiatric treatment (probably exaggerated; one study found that CBT worked well), suggesting a neurally-grounded cause.

All this is to say that we should be paying more attention to the neurological basis for these diseases. I haven’t run across any good fMRI studies of patients with somatiform disorders, both at rest and when suffering from the disorder. It’d be an interesting direction to explore.