From disease to delirium: managing the declining elderly patient. Many geriatric patients have concurrent physical and psychiatric illnesses, but at times it may be difficult to determine which is primary. Delirium, a transient syndrome that presents with psychiatric symptoms, is usually the manifestation of an organic disorder and, if undetected and untreated, can be fatal. Clinicians, therefore, must learn to recognize the syndrome, search diligently for the underlying etiology, and treat accordingly. 