Delusional disorder is described in DSM-V and ICD-10 as characterized either of a single delusion or of a set of related delusions which are long-lasting (one month or longer), but where the criteria for schizophrenia have not been met. In accordance with DSM-V, hallucinations, if present, are not prominent and are related to the delusional theme, functioning is not markedly impaired, and behaviour is not obviously bizarre or odd.