[Neurophysiology and ageing. Definition and pathophysiological foundations of cognitive impairment]

Brain ageing is produced by various morphological, biochemical, metabolic and circulatory changes, which are reflected in functional changes, whose impact depends on the presence or absence of cognitive impairment. Because of brain plasticity, together with redundancy of the distinct cerebral circuits, age- related deterioration of the brain at various levels does not always translate into loss of brain function. However, when the damage exceeds certain thresholds, there is age-related cognitive impairment, which increases the risk of developing various neurodegenerative diseases such as Alzheimer disease. Genetics, together with lifestyle, diet, and environmental factors, etc, can trigger the development of these diseases, which provoke cognitive impairment. This article discusses the most important age-related changes in the brain, as well as the pathophysiological foundations of cognitive impairment.