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Atypical forms of Alzheimer's disease (AD) have been described for a long time, but it is only recently that language, frontal, and visuospatial variants have been incorporated into the clinical diagnosis and research criterion of AD. It is now possible to establish an in vivo diagnosis of the frontal variant of AD (fv-AD) with a high degree of probability thanks to the link between the neuropsychological profile and biomarkers. However, the neuropsychological and behavioral profiles of patients with fv-AD are still poorly understood, sometimes leading to misdiagnosis, especially when it comes to the behavioral variant of frontotemporal lobar degeneration (bv-FTLD). Social cognition assessment seems to be a promising tool for the differential diagnosis between fv-AD, AD, and bv-FTLD.