[Alzheimer's and related diseases: toward earlier and more accurate diagnosis].

Because of population ageing, the prevalence of Alzheimer's disease (AD), the most common cause of dementia, increases progressively. This condition is now considered as a public health priority. New disease modifying therapeutic strategies could be available in the next few years that would necessitate an accurate and early diagnosis of the disease. Recently developed diagnostic tools are being assessed. Development of structural brain imaging allows to measure the hippocampus volume. Metabolic imaging can assess a broad range of functional parameters such as cerebral blood flow and dopaminergic activity with single photon emission computed tomography, cerebral glucose metabolism and cerebral amyloid burden with positron emission tomography. Those imaging methods are under evaluation to appreciate cerebral abnormalities that may occur earlier than structural ones. Cerebrospinal fluid biomarkers, in particular amyloid and tau peptides, allow us to look at in vivo biochemical cerebral changes related to AD, before possible serum biomarkers. Studies are under way to confirm the relevance of these new diagnostic tools. It will help us to improve evaluation of patients with AD or related diseases.