To determine if psychiatric symptoms proceed the onset of behavioral variant frontotemporal dementia in a subset of patients.

Prior investigations have suggested an association of psychiatric symptoms with behavioral variant frontotemporal dementia (bvFTD). This association has primarily involved the presenting symptoms of bvFTD and specific associations with C9orf72 and other genetic forms of the disorder. Less is understood about psychiatric symptoms as a prodrome, temporally separated from the recognized clinical onset of bvFTD.

We retrospectively reviewed the psychiatric histories and clinical characteristics of 137 patients with a diagnosis of clinically probable bvFTD. The age of onset and symptomatology of psychiatric symptoms as well as for frontotemporal dementia were included in the study. Clinical history, past medical history, social history, medications, mental status examination, neuropsychiatric testing, and physical examinations were also reviewed. Additionally, imaging and pathology reports were also evaluated when available.

Among the 137 patients reviewed, 15 patients had a preceding history of mood disorders, often not typical of traditional psychiatric diagnoses, but manifesting depressive, manic spectrum, and suicidal symptoms for 1-10 years prior to the clear onset of a recognizable criterion for bvFTD.  On evaluation of imaging studies, these patients were found to have had predominant temporal lobe involvement. Similar mood-related symptoms were also found in the relatives of these patients when looking into available family history.

We conclude that non-typical mood changes, particularly in those with a family history, may be a harbinger of the development of a temporal-predominant bvFTD.