According to German psychiatrist Emil Kraepelin, patients with delusional disorder remain coherent, sensible and reasonable. The "Diagnostic and Statistical Manual of Mental Disorders" (DSM) defines six subtypes of the disorder characterized as erotomanic (belief that someone is in love with one), grandiose (belief that one is the greatest, strongest, fastest, richest, or most intelligent person ever), jealous (belief that one is being cheated on), persecutory (delusions that the person or someone to whom the person is close is being malevolently treated in some way), somatic (belief that one has a disease or medical condition), and mixed, i.e., having features of more than one subtype. Delusions also occur as symptoms of many other mental disorders, especially the other psychotic disorders.