Apathy is a behavioral symptom present in many neurological and psychiatric pathologies and it’s defined as a quantitative reduction of voluntary, goal-directed behaviors. Today, apathy is assessed by questionnaires administered to the patient and/or caregiver and providing score, which compared to a threshold (norms), is able to determine the degree of apathy (clinical evaluation). However, this method of evaluating apathy is biased by the subjective nature of the patient or caregiver’s perspective. Most of time, the patient is unaware of his or her real disorder (anosognosia). The objective of this thesis entitled "DEVELOPMENT OF A CLASSIFICATION SYSTEM FOR ASSESSING APATHY'S DEGREE IN PATIENTS WITH BEHAVIOURAL VARIANT OF FRONTOTEMPORAL DEMENTIA" is to address the specific question concerning the limitations of the assessment of neuropsychiatric symptoms (NPS) using interviews and rating scales, carrying out an objective and quantitative assessment of apathy.