[Alzheimer's disease: a biological disorder?]

Alzheimer's disease: a biological disorder? Alzheimer's disease often begins clinically with memory problems progressively followed by aphasia, apraxia, agnosia and behavioral disturbances. Recent studies of biological markers of cerebrospinal fluid or amyloid and tau PET imaging have shown that abnormalities can begin one to two decades before the onset of symptoms. This clinically silent phase is a biological phase where neurons fight the toxic effects of amyloid and tau accumulations as well as neuroinflammation. An ATN biological classification has been proposed (A: amyloid, T tau, N: neurodegeneration). The discovery of blood or other biomarkers should allow detection of this silent phase leading to the setup of therapeutic trials when brain lesions are minimal and neurons less affected, to be able to prevent the late cognitive decline of this disease.