Patients with frontotemporal dementia (FTD) have major behavioral troubles and a loss of insight. These factors contribute to reduce self-awareness and recognition of identify of others and by others. Autobiographical amnesia, loss of insight and executive dysfunctions are the major reasons of vulnerable "self" in FTD. Mind representation deficits, decrease of perception of emotions and semantic amnesia contribute to reduced recognition of the relative's identity. Alterations of body expressions, social disinhibition, changes in social and religious values decrease the recognition of patient's identity by the relatives. Different psychological components of identity are modified by the FTD such as feeling of unity, of consistency, of temporality and of affiliation. The fact that brain lesions of FTD are focalized can contribute to understand the biological knowledge of "identity". To know the neurological substrate of alterations of identity, this can help to improve the empathy of the suffering caregivers for the patient.