[Biomarkers of Alzheimer disease]

Cognitive impairment is one of the most abundant age-related psychiatric disorders. The outcome of cognitive impairment in Alzheimer's disease has both individual (the patients and their families) and socio-economic effects. The prevalence of Alzheimer's disease doubles after the age of 65 years, every 4.5 years. An etiologically heterogenic group of disorders related to aging as well as genetic and environmental interactions probably underlie the impairment in Alzheimer's disease. Those factors cause the degeneration of brain tissue which leads to significant cognitive dysfunction. There are two main hypotheses that are linked to the process of neurodegeneration: (i) amyloid cascade and (ii) the role of secretases and dysfunction of mitochondria. From the therapeutic standpoint it is crucial to get an early diagnosis and start with an adequate treatment. The undeniable progress in the field of biomarker research should lead to a better understanding of the early stages of the disorder. So far, the best recognised and described biomarkers of Alzheimer's disease, which can be detected in both cerebrospinal fluid and blood, are: beta-amyloid, tau-protein and phosphorylated tau-protein (phospho-tau). The article discusses the usefulness of the known biomarkers of Alzheimer's disease in early diagnosis.