A central criticism of the book lies with its general lack of concern for diagnostic validation. Many historical figures are said to be manic-depressive, and a number of classic symptoms of the disorder are invoked, appearing to validate the diagnosis. Verification of the diagnosis in individuals portrayed, however, does not appear to constitute a serious concern of the text. Many people—including Elvis—are assumed to have been manic-depressive, but more confirmation of the diagnosis is needed before pursuing more extensive discussions of the individual’s condition. It would have been especially helpful if differential diagnosis of depression from substance abuse, particularly alcohol use disorders, which are well documented among artists, could have been better delineated for readers who may not appreciate how alcohol and drug abuse can create states that mimic affective disorders.