[Prognosis and progression of cognitive impairment. Preventive measures].

Because of the substantial increase in population ageing, age-related processes, such as dementia and Alzheimer disease (AD), are becoming highly prevalent. The course of this disease, including preprodromic phases, lasts at least 20 years. The presence of comorbidities, especially those of vascular origin, can trigger and aggravate disease progression. On the other hand, cognitive reserve, the absence or control of comorbid factors and healthy lifestyles can protect or modify -in the sense of slow down- disease progression. Knowledge of the phases of AD and their functional impact on affected individuals helps to identify the average prognosis and, in particular, to establish and predict care plans based on the individual's needs.