The behavioral variant of frontotemporal dementia (FTD) often begins with psychiatric symptoms, including changes in personal conduct and/or interpersonal behavior. Prior to developing cognitive impairment, differentiating FTD from primary psychiatric disorders might be challenging.

This work presents a case of a manic episode with psychotic features in a 61-year-old man, whom personality changes and daily life difficulties arouse and persist after optimal management of the active manic and psychotic symptoms. Neuropsychological assessment detailed severe deficits among visuospatial and planning performances. Structural neuroimaging (CT-scan) primary revealed a global pattern of brain volume reduction. Severe perfusion deficits on frontal and both parietal lobes were shown on 99mTc-HMPAO single-photon emission computed tomography (SPECT). The hypothesis of probable FTD (behavioral variant) was established.

The present case highlights how putative atypical and late-onset forms of bipolar disorder (BD) might instead progress to FTD. Several links are being advanced between the BD and FTD, for instance the close involvement of the C9ORF72 gene in a group of BD patients which progresses to dementia. These relations have actually been on focus recently. The field is however still relatively unexplored.