BACKGROUND: The behavioral variant frontotemporal dementia (bvFTD) shares some clinical features with severe mental disorders, such as bipolar affective disorder (BAD), schizophrenia (SCZ), and schizoaffective disorder (SZA), and at least for a small subgroup of patients, these conditions may share similar pathological genetic mutations.

OBJECTIVES: To investigate the frequency of a past medical history satisfying diagnostic criteria for BAD, SCZ, and SZA in a bvFTD outpatient sample, and to compare the clinical profile of patients with and without a positive history.

METHODS: Cross-sectional study in which participants were consecutively selected after receiving a diagnosis of probable bvFTD and had a caregiver interviewed with SCID-I. The sample was categorized into two groups: with (bvFTD+) or without (bvFTD-) prior medical history satisfying diagnostic criteria for BAD/SCZ/SZA. Subjects went through cognitive, functional, and neuropsychiatric evaluations.

RESULTS: Overall, 46 bvFTD patients were included; bvFTD+ patients accounted for 36.9% of the sample. The main nosology fulfilling criteria was BAD (76.5%). The groups differed in Neuropsychiatric Inventory scores (p = 0.01), use of antipsychotics (p = 0.01), family history of psychosis (p = 0.01), presence of primitive reflexes (p = 0.04), Frontal Assessment Battery performance (p = 0.01), Ekman's facial emotion recognition test (p = 0.03), frequency of apathy (p = 0.03), and stereotyped behavior (p = 0.01). All these parameters were more frequent/worse in the bvFTD+ group.

CONCLUSIONS: A prior medical history compatible with BAD/SCZ/SZA was found in more than 1/3 of this sample of bvFTD patients and was associated with subtle distinctive clinical features.