SOPHIA ANTIPOLIS, France — High blood pressure is usually a condition that causes patients to fear for their heart health. A study by researchers in the United Kingdom say even a small change can eventually mean trouble for your brain as well. A report by the European Society of Cardiology finds hypertension, especially during middle age, can lead to increasing brain damage in the elderly.
In particular, researchers say diastolic blood pressure (the bottom or second number) has a strong connection to brain damage later in life. Of even more concern, blood pressure that is higher but within the limit not requiring treatment can still raise the risk of “white matter hyperintensities” (WMH).
This form of brain damage has a link to stroke, dementia, physical disabilities, depression, and a drop in thinking abilities. It shows up on MRI scans as brighter regions which reveal damage to the blood vessels in the brain.
“Not all people develop these changes as they age, but they are present in more than 50% of patients over the age of 65 and most people over the age of 80 even without high blood pressure, but it is more likely to develop with higher blood pressure and more likely to become severe,” Dr. Karolina Wartolowska from the University of Oxford says in a media release.
Small changes in blood pressure make big differences for the brain
The study examined just over 37,000 patients in the U.K. between 40 and 69 years-old. Researchers gathered initial health information about these people between 2006 and 2010, before getting follow-up readings and MRI scans between 2014 and 2019. The team also adjusted for varying health factors like age, sex, smoking habits, blood pressure, and a history of diabetes.
“To compare the volume of white matter hyperintensities between people and to adjust the analysis for the fact that people’s brains vary slightly in size, we divided the volume of WMH by the total volume of white matter in the brain. In that way, we could analyze the WMH load, which is the proportion of the WMH volume to the total volume of white matter,” explains Dr. Wartolowska.
Researchers discovered that a higher load of WMH also has a strong connection to systolic blood pressure, the top or first number. The strongest connection however, comes from changes in diastolic blood pressure readings which come from the patient’s past. In particular, blood pressure readings coming before the patient turns 50 play a major role in determining future brain damage.
For every 10mmHg increase in systolic blood pressure above the norm (120mmHg) the amount of WMH would increase by 1.126 times. For every 5mmHg in diastolic blood pressure, the amount of brain damage would go up 1.106 times.
Better health now can mean a stronger brain later
Wartolowska says that patients with the largest WMH loads could trace 24 percent their brain damage problems to having systolic blood pressure above 120mmHg. Another seven percent of the damage could be traced to having diastolic blood pressure above 70mmHg.
“The study showed that diastolic blood pressure in people in their 40s and 50s is associated with more extensive brain damage years later… Many people may think of hypertension and stroke as diseases of older people, but our results suggest that if we would like to keep a healthy brain well into our 60s and 70s, we may have to make sure our blood pressure, including the diastolic blood pressure, stays within a healthy range when we are in our 40s and 50s,” the clinical research fellow at the Centre for Prevention of Stroke and Dementia says.
“Our results suggest that to ensure the best prevention of white matter hyperintensities in later life, control of diastolic blood pressure, in particular, may be required in early midlife, even for diastolic blood pressure below 90mmHg, whilst control of systolic blood pressure may be more important in late life. The long time interval between the effects of blood pressure in midlife and the harms in late life emphasizes how important it is to control blood pressure long-term, and that research has to adapt to consider the very long-term effects of often asymptomatic problems in midlife.”
The team warns that white matter brain damage can also be influenced by how delicate brain blood vessels are. More pressure can weaken them and cause the linings of these vessels to leak. Diastolic pressure issues can also cause larger blood vessels to stiffen over time, causing harmful changes in heart beats and blood flow to the brain.
The study appears in the European Heart Journal.