The course of human endeavor, or life, as one of the most important elements in the evolution of the species, is marked by psychologic changes which are often more obvious than the physical. Whether these have become more frequent or whether attention has been more closely focused on them is not so important as the fact that modern research is becoming more concerned with their influences. The rapidly varying activities of modern life from business and social points of view have modified environmental states in their spiritual, social, economic and domestic, as well as sensual, aspects. Mental reactions have multipled, fixations and habit patterns have been altered, and complexes, repressions and other psychopathic effects correspondingly developed or elaborated. These are sometimes so marked and severe as to occasion a response which is comparable to shock or trauma from other causes.
The influence of fright as well as anxiety, fatigue, anger,
MOLEEN GA. INFLUENCE OF EMOTIONAL SHOCK ON THE GASTRO-INTESTINAL TRACT IN THE PSYCHONEUROSES. JAMA. 1930;95(13):910–913. doi:10.1001/jama.1930.02720130006002