[Neurosyphilis: a rare cause of dementia].

Introduction: Neurosyphilis had to be evoked in the face of an atypical dementia.

Case Record: We describe the case of a 65-year-old man who presented with neurosyphilis suspected to precede behavioral and cognitive problems in the context of risky sexual behavior and was confirmed by serologic tests in the cerebrospinal fluid.

Discussion: This case proves the necessity to investigate the possibility of neurosyphilis in subjects with dementia syndrome which does not correspond to classic etiologies.