In Russia, arterial hypertension occurs in 40-47% of adults. It is known to be a risk factor for impairment of cognitive abilities (memory, concentration, etc.) and the development of dementia. Whether the duration of hypertension is associated with the risk of cognitive impairment was not previously known.
In the Russian clinical guidelines, hypertension is a chronic increase in systolic (upper) blood pressure above 140 millimeters of mercury (mm Hg), and diastolic (lower) blood pressure above 90 mm Hg.
Prehypertension is said to be when systolic blood pressure rises to 120-139 mm Hg. or diastolic – up to 80-89 mm Hg. Previously, this pressure was called “high normal”.
Brazilian scientists analyzed data from a large study of cognitive functions. More than seven thousand people took part in it, which was observed for about four years. All participants took tests for memory, fluency, attention and concentration.
The study authors write that they expected the risk of cognitive impairment and dementia to be higher in people who had hypertension for longer. However, the data they obtained indicate something else: in addition to the fact that people with systolic from 121 to 139 mm Hg. and diastolic from 81 to 89 mm Hg (they did not take medications for hypertension) deterioration of cognitive abilities is more common, it turned out that, in general, the phenomenon of deterioration of such abilities is characteristic not only of the elderly, but also of middle age.
According to the authors of the study, these data show that prehypertension can also dangerously affect a person’s cognitive abilities.
Scientists have found that the acceleration of the process of weakening memory and deterioration of thinking does not depend on at what age the hypertension began and how long it lasted. Cognitive impairment progressed in both participants under the age of 55 (in the study they were combined into a middle-aged group) and older people.
Cognitive abilities deteriorated faster in people who had poor control over their hypertension and whose blood pressure remained high. At the same time, the reasons for poor control varied: lack of treatment, ineffective treatment, severe forms of the disease.
Why are cognitive abilities impaired in hypertension?
Several mechanisms may link high blood pressure to brain damage, scientists point out. Due to the regular stress associated with pressure, atherosclerosis and other pathologies (for example, lipo-hyalinosis) develop more easily in the blood vessels of the brain. This leads to a deterioration in the blood supply to this organ. Lack of oxygen in the brain can lead to chronic inflammation. Another mechanism of action of hypertension may be associated with a dysfunction of the barrier between the blood vessels and the brain. This contributes to the easier penetration of toxic substances into the brain. Among the consequences to which these mechanisms lead are brain atrophy, chronic hypoxia, the formation of small foci of necrosis. They are associated with the development of both dementia and some other neurological pathologies.