Defining Delusional Disorder

Our modern conception of delusional disorder is based on Kraepelin's original formulations. He noted that in contrast to patients with dementia praecox, there was a subset of patients who held delusional beliefs but did not manifest hallucinations. Furthermore, functional capacities were generally preserved and the downhill course he saw as central to the dementia praecox diagnosis was not shown. Nevertheless, Kraepelin often had difficulty definitively diagnosing these individuals. Delusional disorder remains to this day a controversial and complex disorder.