[Diagnostic alertness to patients having a personality disorder with changing symptoms]

The diagnosis of mood disorders in patients with a personality disorder is complex because there may be a significant overlap of symptomatology between both disorders. A 33-year-old man with a borderline personality disorder, for which he had been treated for several years with marginal success, developed a depression that was not recognised and treated until late. Besides the similarity between the two disorders, emotional and personal factors on the part of the physician played an important role in the failure to diagnose the depression. In such complex situations, the use of practice guidelines may be helpful because these prescribe professional attitudes that, in this case, would probably have prevented the non-recognition of the depression.