disorder without agoraphobia, psychosomatic skin disorder, and possibly Chagas disease of the stomach, which he suggested "was first active and then became inactive, permanently injuring the parasympathetic nerves of his stomach and making it more sensitive to sympathetic stimulation and hence more sensitive to the psychosomatic impact of his anxieties. An organic impairment best explains the lifelong chronicity of many of his abdominal complaints." Thus, the psychological aspects of Darwin's illness might be both a cause and an effect of Darwin's illness. D.A.B. Young wrote in a Royal Society journal in 1997 that the psychogenic view of Darwin's sickness "holds the field". The proponent of Chagas disease, Dr. Saul Adler, stated that Darwin may have suffered both from Chagas disease and from "an innate or acquired neurosis". At a conference hosted by the University of Maryland, Baltimore, School of Medicine on the topic of Darwin's ailments, gastroenterologist Dr. Sidney Cohen of Thomas Jefferson University concluded that in his early years Darwin had suffered cyclic vomiting syndrome, but as he had brought up secretions such as stomach acid rather than food, this had not affected his weight and nutrition. He believed that Chagas disease contracted during the Beagle voyage was consistent with Darwin's account of his fever at that time and his later gastrointestinal complaints, as well as the heart disease later in life that led to Darwin's death. In addition, Helicobacter pylori which often occurs with Chagas would have caused Darwin to have peptic ulcer disease. Hereditary disease Many of Darwin's children suffered from similarly vague illnesses for much of their early lives. Darwin himself—concerned with heredity—wondered if he had passed on his generally infirm condition to his children, and was especially interested if their mother Emma Wedgwood, his cousin, was also responsible. His concerns later in life with the effects of inbreeding were potentially motivated by this personal aspect as well. Contribution to Darwin's work Darwin's illness may have contributed to his long and fruitful career in science. George Pickering, in his book Creative Malady (1974), wrote that Darwin—isolated from social life and obligations of a "normal" scientist, such as administrative and teaching work—had ample time and material comforts for research, thought, and writing extensively, which he did. Despite long periods of unproductivity due to ill health, he produced much research. Darwin often complained that his malady robbed him of half a lifetime, but even so, many believe that