Of course, it may be true that some of these disorders represent true syndromes, in that some of the time the multiple dimensions stem from a common cause, even though the dimensions do not always share the same etiology (analogous to the flu example above). If that turned out to be true, then the validity of the syndrome description would nevertheless in part be a function of the precision with which each dimension within the syndrome had been defined and studied. However, the failure (to date) to find evidence for this possibility (Kupfer et al., 2002) suggests it is unlikely.
