Performance of AclarusDx® a Blood-Based Transcriptomic Test for AD, in French Patients Newly Referred to a Memory Center

The objective of this study is to apply AclarusDx™ signature in 600 patients newly referred in french memory centers. Only AclarusDx™ will be added to the panel of tests usually performed at the centers to establish diagnosis. AclarusDx™ will be used for investigational use only, not for diagnostic purpose. The ultimate goal is to define the clinical utility of AclarusDx™ to provide physicians with a tool that will help them in making the diagnosis of Alzheimer's Disease (AD). The primary objective is to estimate the prevalence of positive AclarusDx™ in patients diagnosed AD in the population of primary consultants. This population of primary consultants consists of patients with cognitive impairment and / or a memory complaint requiring specialized exploration using AclarusDx™ blood test and which may be potentially related to multiple and different etiologies. The secondary objectives are: * Assess the prevalence of positive AclarusDx™ in relation to other diagnoses (MCI, vascular dementia ...) established by the physician investigator at the end of specialized assessment. * Identify the demographic factors anamnestic, clinical, biological and imaging associated with positivity of AclarusDx™ * Identify the demographic factors anamnestic, clinical, biological and imaging associated with the diagnosis of AD and other diagnoses. * Determine the contribution of AclarusDx™ in the usual battery of tests performed for diagnostic approach to Alzheimer's disease and to identify a possible association of interest with one or more endpoints (clinical, neuropsychological, brain, biological imaging). * Assess: diagnostic status at 6 and 12 months, and the MMSE and IADL at 6 and 12 months. * assess the predictive value of AclarusDx™ achieved during the initial visit to the diagnosis of AD is 12 months. * Evaluate AclarusDx™ predictive value to 12 months