This Editorial highlights how difficult is the correlation between Mood Disorder and Ischemic Heart Disease. In particular, it highlights the serious problem of suicide risk. This long-standing problem, object of controversy in the scientific literature, requires insights that should avoid simple surveys entrusted to the questionnaires, and the subjectivity of the clinical judgment. The text of the Editorial suggests the opportunity for substantial insights in the study of biological markers that give greater certainty of psychiatric diagnosis. The effort of the authors, in this sense, has proved highly effective in recognizing some of the major psychiatric disorders (Major Depression, Bipolar Disorder, Obsessive Compulsive Disorder and suicidal thoughts). Much work, however, remains to be done. The further suggestion which can be obtained from the script is that the complexity of mental phenomena must be faced with complex mathematical tools, to find diagnostic certainty and not diagnosis of opinion.