Schizophrenia and delusional disorder (DD) are non-affective psychoses with overlapping symptoms but distinct traits. Schizophrenia typically begins in late teens or early adulthood, featuring delusions, hallucinations, cognitive deficits, and negative symptoms, often leading to functional decline. DD, emerging in middle age, is characterized primarily by delusions, preserving cognitive and daily functioning. Persecutory delusions are common in both, but DD delusions are more plausible. Depression frequently co-occurs in DD, raising suicide risk, while schizophrenia has higher rates of hallucinations and cognitive impairments. Treatments include antipsychotics, with DD requiring lower doses and more frequent use of antidepressants. Cognitive-behavioral therapy is effective for delusions in both disorders.

DD is much rarer, with distinct epidemiological differences. Both conditions require attention to safety due to risks of suicide and harm linked to delusions. The review highlights the importance of therapeutic alliances in DD and the need for rigorous research to refine treatments and improve outcomes. Recognizing these differences is essential for tailored care and advancing clinical practice.

Reference: González-Rodríguez A, Seeman MV. Differences between delusional disorder and schizophrenia: A mini narrative review. World J Psychiatry. 2022 May 19;12(5):683-692. doi: 10.5498/wjp.v12.i5.683. PMID: 35663297; PMCID: PMC9150033.