Commentary: Diagnostic Challenges.

The 3 cases presented in this issue highlight diagnostic challenges in evaluating and treating patients with complicated presentations. The first case involved a man with mild neurocognitive disorder due to Alzheimer disease accompanied by depressive and anxiety symptoms and what appeared to be previously undiagnosed attention-deficit/hyperactivity disorder. The second case involved an unusual case of shared psychotic disorder involving a woman with a primary diagnosis of bipolar disorder and her husband with posttraumatic stress disorder. The third case involved a patient with a history of multiple diagnoses who presented with catatonic symptoms, obsessive-compulsive disorder characterized by religious scrupulosity, and some features of obsessive-compulsive personality disorder. These reports illustrate the challenges in evaluating and treating patients whose clinical presentations may not fit neatly into a diagnostic category or that have a nontraditional presentation.