Early Onset Alzheimer Disease (EOAD) is a rare condition, frequently associated with genetic causes. The dissemination of genetic testing along with biomarker determinations have prompted a wider recognition of EOAD in experienced clinical settings. However, despite the great efforts in establishing the contribution of causative genes to EOAD, atypical disease presentation and clinical features still makes its diagnosis and treatment a challenge for the clinicians. This review aims to provide an extensive evaluation of literature data on EOAD, in order to improve understanding and knowledge of EOAD, underscore its significant impact on patients and their caregivers and influence public policies. This would be crucial to define the urgency of evidence-based treatment approaches.