Which condition is characterized by the presence of delusions without other symptoms of schizophrenia?

Delusional disorder is characterized primarily by the presence of one or more delusions that persist for at least one month. Unlike schizophrenia, individuals with delusional disorder do not exhibit other significant symptoms such as hallucinations, disorganized thinking, or negative symptoms that are usually associated with schizophrenia. This distinction is vital because it highlights that the person's functioning outside of the delusional beliefs is often not markedly impaired, and they do not meet the full criteria for schizophrenia or other related disorders.

In contrast, schizophrenia involves a broader range of symptoms including not just delusions, but also hallucinations, disorganized speech, and negative symptoms that impact various aspects of an individual’s life. Brief psychotic disorder involves the sudden onset of psychotic symptoms, including delusions or hallucinations, but these last for less than one month, distinguishing it from the persistent nature of delusions in delusional disorder. Schizoaffective disorder encompasses both mood disorder symptoms (such as depression or mania) and symptoms of schizophrenia, leading to a more complex clinical presentation than delusional disorder alone.

Thus, delusional disorder specifically focuses on the presence of delusions without accompanying symptoms characteristic of schizophrenia, making it the correct answer.