CSF biomarkers and genetic studies of ApoE make a major contribution to the positive diagnosis of Alzheimer's disease. Our aim was to compare the clinical data, biological and genetic results of the AD population with a group of patients with non-Alzheimer's dementia (D n-MA) and a control population. Methods: This was a retrospective analytical study conducted at the neurology department of the Sahloul University Hospital in Sousse over 3 years (January 2015-December 2017) and included 227 patients meeting the DSM-5 criteria for TNC. The aetiological diagnosis was based on international criteria established through neuropsychological assessment, imaging, CSF biomarker testing and ApoE polymorphism study. Results: The mean age of onset of AD was 70.79 ± 8.93 years. An early age of onset (<65 years) was found in 21.9% of cases. The sex ratio was 1. Decreased concentrations of AB40 and AB42 were found in the AD group, with sensitivity of 82% and 86% respectively, and specificity of 85% and 83%. Total Tau and P181-Tau protein concentrations were higher.