Late-onset OCD as presenting manifestation of semantic dementia.

Semantic dementia (SD) is a neurodegenerative disease belonging to the spectrum of frontotemporal dementia that presents with loss of memory for words and prevalent left temporal pole atrophy. Behavioral disorders, particularly obsessive-compulsive symptoms, are frequent during the course of the disease. We describe a patient presenting with late-onset typical obsessive–compulsive disorder (OCD) that lasted for 10 years as an isolated condition before developing clinical and neuroimaging features of SD. This case alerts clinicians that late-onset OCD may be a psychiatric presentation of a neurodegenerative disorder such as frontotemporal dementia and requires an accurate diagnostic work-up.