FROM A MAGNESIUM WEBSITE:
Anxiety and Psychiatric Disorders
Magnesium deficiency causes increased levels of adrenaline, which can lead to a feeling of anxiety. Rats who become magnesium deficient have an increased level of urinary catecholamine excretion (a by-product of adrenaline).
Researchers in Spain found a correlation between anxiety disorders and hypermobility. In fact, they found that patients with anxiety disorder were over 16 times more likely than control subjects to have joint laxity. If you put the study results together, then there's a link between anxiety and hypermobility, a link between anxiety and mitral valve prolapse, and a link between mitral valve prolapse and hypermobility.
These studies tell us that anxiety disorders occur in many people who simply have mitral valve prolapse and/or joint hypermobility, meaning anxiety disorders are not specific to EDS or any particular connective tissue disorder. Marfans also have mitral valve prolapse and joint hypermobility which would lead one to conjecture that they, too, have anxiety related disorders. As it turns out, a connection between Marfans and anxiety related disorders has been noted.
A study in Bulgaria also found magnesium abnormalities in patients with schizophrenia and depression. The authors thought the schizophrenia and depression caused the magnesium deficiencies, but I disagree that that was necessarily the case. When you look at this study within the context of all the other studies mentioned in this section, it is more likely that the magnesium abnormalities caused the mental illness. (There are quite a few studies on magnesium and mental illness on Medline. I just included a few to highlight my points.)
In a study from England, there was a strong association for more disturbed and excitable patients to have abnormal (either high or low) magnesium levels. The authors thought that the patients who seemed most disturbed may have some abnormality of magnesium metabolism.
For more on this topic, see the section on Anxiety and Depression - overlooked nutritional causes at http://www.ctds.info/5_13_magnesium.html#anxiety