Signature size in the psychiatric diagnosis: a significant clinical sign?

To test the hypothesis that patients' signatures may have a useful potential in making psychiatric diagnoses, the authors conducted a correlation study between signature sizes and psychiatric diagnoses. 252 medical records at St. Louis State Hospital in Missouri, USA, were randomized for the measurement of the signature sizes and assessment of DSM-III diagnoses. Analysis of variance and pair-wise comparison show that the signature size in the manic group is significantly larger than those of any other categories of psychiatric diagnoses (p less than 0.05), and that the signature size of organic mental disorder is significantly larger than those of the normal group (p less than 0.05). The authors suggest that further studies are needed to develop the clinical significance, if any, for interpreting patients' signatures.