Frontotemporal dementia - behavioral variant (FTD-bv), is an important cause of disability in adults under 65 years of age. It is postulated as a neurological disease with predominantly psychiatric manifestations and, therefore, constitutes a frequent differential diagnosis in psychiatric pathologies of not early onset. Although traditionally the absence of memory impairment was considered among its diagnostic criteria - as opposed to Alzheimer's disease (AD) -, several studies have found until 15% of prevalence of cases with frank mnemonic deterioration, as well as neuroimaging of one and the other can have overlap. Currently, the presence of "phenocopy syndromes" - clinical pictures similar to FTD-bv but without cognitive impairment- and cases of AD with disinhibition and behavioral symptoms, make the clinical diagnosis more complex and suggest the insufficiency of the established diagnostic criteria and the necessary adoption of paraclinical criteria. To this purpose, we present an illustrative case of FTD-bv with memory impairment and Alzheimer-like neuroimages, and we review the pertinent bibliography.