This paper details the case of a 64-year-old woman who presented to the psychiatry service with worsening mood in the context of a diagnosis of obsessive-compulsive disorder (OCD). On further examination she was found to have clinical findings consistent with frontotemporal lobar degeneration of the non-fluent progressive aphasia subtype. At post-mortem she was found to have progressive supranuclear palsy. We argue, in retrospect, that her OCD was likely prodromal to the development of her dementia. This case highlights the fact that frontotemporal lobar degeneration/progressive supranuclear palsy (FTLD/PSP) and other "tauopathies" represent a complex group of neurodegenerative disorders that may masquerade for many years as refractory psychiatric disorders.