The purpose of this study is to assess the performance of AclarusDx™, an investigational blood test detecting gene expression information, and intended to help physicians in making an Alzheimer's Disease diagnosis in patients having memory complaint and/or cognitive impairments.

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

Inclusion Criteria:

• male and female adult patients
• suffering from cognitive impairment and/or memory complaint and justifying a first clinical investigation at the memory center

Exclusion Criteria:

• patient already followed up by the memory center
• patient unable to comply with study procedures

Patients with cognitive impairment and/or memory complaint justifying a first clinical investigation for diagnosis