What distinguishes Delusional Disorder from Schizophrenia?

Delusional Disorder is characterized by the presence of one or more delusions that persist for at least one month. In contrast, Schizophrenia involves a broader range of symptoms, including not only delusions but also hallucinations, disorganized thinking, and negative symptoms, which are outlined in Criterion A of the DSM-5. The distinction lies in the absence of Criterion A symptoms in Delusional Disorder; individuals do not experience the full spectrum of psychotic features that are diagnostic for Schizophrenia. This differentiates the two disorders fundamentally, as Delusional Disorder typically does not involve the significant level of impairment in functioning seen in Schizophrenia, nor does it exhibit the diverse symptomatology associated with it.

The duration of symptoms, while important, is not the primary distinguishing factor, as both disorders require significant duration for diagnosis. Furthermore, bizarre hallucinations are particularly indicative of Schizophrenia and are not a hallmark of Delusional Disorder. Negative symptoms may be present in both conditions but are more prominent in Schizophrenia, making the lack of Criterion A symptoms the most distinguishing factor between the two disorders.