For those of you who benefit from dex: I'm wondering if you have a family history of autoimmune diseases, such as Graves', spondylitis, or celiac (and associated osteoporosis).

Dex works by stimulating certain nerve receptors (including those for adrenaline and dopamine). Maybe our immune systems are incorrectly turning off those nerve receptors, and the reason dex helps is that it counteracts that effect by stimulating them.

Just a theory.