Recently, an international journal entitled "middle blood pressure is associated with the severity of white matter hyperintensities: analysis of the UK Biobank Cohort" In the study report, scientists from Oxford University and other institutions have found that in the elderly, blood pressure is higher than normal or is related to more extensive brain damage.
In particular, the researchers also found a strong correlation between diastolic blood pressure between age 50 and brain damage later in life, even though diastolic blood pressure is considered to be in a healthy range. In this study, the researchers studied 37041 participants aged 40-69 from a biological sample bank, and collected MRI brain scan data of these participants. The researchers looked for a white matter high signal (WMH, white matter) In addition, the researchers also found that WMH was associated with the risk of stroke, dementia, physical disability, depression and decreased thinking ability.
Wartolowska, a researcher, said that not all people will experience these changes with age, but 50% of people over the age of 65 will have these changes, and most people over 80 will have these changes even if they do not have high blood pressure, but as the body's blood pressure rises, patients are more likely to have these changes, and they will become more and more serious. When the participants were recruited to the UK Biobank from March 2006 to October 2010, the researchers collected their information, followed by data including MRI scans from August 2014 to October 2019. In addition, the researchers adjusted the relevant information, including age, gender, risk factors such as smoking and diabetes, diastolic blood pressure and systolic blood pressure; systolic blood pressure refers to the highest blood pressure that the body can reach each time the heart beats, which is the highest value of blood pressure measurement.
In order to compare the white matter hyperintensity (WMH) between different individuals and to adjust to the fact that people have different brain sizes, they divided the volume of WMH by the total volume of white matter in the brain, so as to analyze the load of WMH, that is, the proportion of WMH volume in the total white matter volume. The researchers found that higher WHM load is closely related to the current body systolic blood pressure, but the strongest correlation is the past individual systolic blood pressure, especially when they are under 50 years old; any increase in blood pressure (even lower than the treatment threshold of 140 mmHg systolic blood pressure and lower than 90 mmHg diastolic blood pressure) is directly related to the increase of WMH, especially for people taking drugs to treat hypertension 。
Within the normal range, the average (median) load ratio of WMH increases by 1.126 times for every 10 mmHg increase in systolic blood pressure, and 1.106 times for every 5 mmHg increase in diastolic blood pressure. In the top 10% of the population with the highest WMH load, 24% of the load can be attributed to systolic blood pressure higher than 120 mmHg, and 7% load can be attributed to diastolic blood pressure higher than 70 mmHg It may reflect that in the elderly, the incidence of increased systolic blood pressure may be higher than the incidence of diastolic blood pressure. In this study, the researchers made two findings. First, diastolic blood pressure in people aged 40 and 50 is associated with more extensive brain damage in their brains years later, which means that not only systolic blood pressure, but diastolic blood pressure is also important in preventing brain tissue damage. Many people think that hypertension and stroke are diseases of the elderly, but the results of this study suggest that if we want to maintain a healthy brain at the age of 60 and 70, we may need to ensure that the body's blood pressure (including systolic blood pressure) is maintained in a healthy range at the age of 40 and 50. The second important finding is that any increase in blood pressure above normal range is associated with more white matter in the brain, suggesting that even a slight increase in blood pressure can have a devastating effect on brain tissue before reaching the standard for treatment of hypertension.
In order to prevent high white matter signal in old age, especially to control diastolic blood pressure in early middle age, even if diastolic blood pressure is lower than 90mmHg, it may be more important to control systolic blood pressure in later years. The time interval between the influence of middle-aged blood pressure and the harm in later years is longer, which also emphasizes the importance of long-term blood pressure control. Moreover, this study must consider the importance of long-term blood pressure control Long term effects of asymptomatic problems. The potential mechanisms of WMH include that, over time, increasing pressure directly leads to vascular damage, which damages vulnerable blood vessels in the brain, which leads to intimal infiltration and induces WMH. In addition, diastolic blood pressure may make large blood vessels stiffer over time, thus increasing blood pressure pulses to the brain In turn, it will lead to increased blood pressure, faster blood pressure, and low blood flow between heart beats, resulting in white matter damage.
Since MRI scan has only one time point, researchers can not directly quantify WMH. Other limitations of this study include the need for further analysis to determine the differences between different regions of white matter. Although researchers have revealed the association between smoking and diabetes, the interaction between potentially complex risk factors needs further research and analysis, These include high cholesterol levels, obesity and kidney problems.