EGF and psychotic disorder: Given our special interest in negative symptoms during the design of the study, we placed particular emphasis on examining the possible relationship between the severity of these symptoms (avolition, anhedonia, antisociality, flat affect, alogia) and the blood concentrations of EGF which might be related to negative symptoms and cognitive impairment in this psychosis, which may be indicated by the results of research in Parkinson’s and Alzheimer’s diseases [4,5,6,26,27].