Alzheimer's disease is a chronic neurodegenerative disease with well-defined pathophysiological mechanisms that most often affect the medial temporal lobe and adjacent neocortical structures. Extracellular neural plaques and intercellular fibrils are most common pathological features of Alzheimer's disease, resulting from the accumulation of amyloid β peptides and cytoskeletal changes resulting from hyperphosphorylation and aggregation of microtubule binding tau protein. After the originally established amyloid theory according to which amyloid β was the main bearer of AD pathology, was found that tau protein by its aggregation into oligomers and fibrils greatly contributes to the progression of the disease as well. Despite the numerous studies of AD pathology, it remains unknown why the development of the disease lasts decades before the appearance of the first symptoms, but it is considered that the reason could be diminished ability to remove misfolded, oligomeric and aggregated forms of protein, which accumulate with age. Following unsuccessful therapeutic interventions that target amyloid β, new drugs are aiming at phosphorylation and aggregation of tau protein but we are still awaiting the outcomes of their clinical studies. In addition, the accurate understanding of the mechanisms by which the toxic tau oligomers are spread through the synapse is of great importance for the design of new therapies.