In a new study, researchers found that higher than normal blood pressure is linked to more extensive brain damage in the elderly.
In particular, they found that there was a strong link between diastolic blood pressure (the blood pressure between heartbeats) before the age of 50 and brain damage in later life, even if the diastolic blood pressure was within what is normally considered to be a healthy range.
The research was conducted by a team at the University of Oxford and elsewhere.
The findings come from a study of 37,041 participants enrolled in UK Biobank, a large group of people recruited from the general population aged between 40 and 69 years.
The team looked for damage in the brain called “white matter hyperintensities” (WMH).
These show up on MRI brain scans as brighter regions and they indicate damage to the small blood vessels in the brain that increases with age and blood pressure.
WMH are associated with an increased risk of stroke, dementia, physical disabilities, depression, and a decline in thinking abilities.
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.
In the study, the team found that a higher load of WMH was strongly linked to current systolic blood pressure, but the strongest link was for past diastolic blood pressure, particularly when under the age of 50.
Any increase in blood pressure, even below the usual treatment threshold of 140 mmHg for systolic and below 90 mmHg for diastolic, was linked to increased WMH, especially when people were taking medication to treat high blood pressure.
For every 10mmHg increase in systolic blood pressure above the normal range, the proportion of WMH load increased by an average of 1.126-fold and by 1.106-fold for every 5mmHg increase in diastolic blood pressure.
Among the top 10% of people with the greatest WMH load, 24% of the load could be attributed to having systolic blood pressure above 120mmHg, and 7% could be attributed to having diastolic blood pressure above 70mmHg.
This reflects the fact that there is a greater incidence of elevated systolic rather than diastolic blood pressure in older patients.
The findings showed that diastolic blood pressure in people in their 40s and 50s is associated with more extensive brain damage years later.
This means that it is not just the systolic blood pressure, the first, higher number, but the diastolic blood pressure, the second, lower number, that is important to prevent brain tissue damage.
The team says many people may think of high blood pressure and stroke as diseases of older people, but the results suggest that if they would like to keep a healthy brain well into our 60s and 70s, they may have to make sure their blood pressure, including the diastolic blood pressure, stays within a healthy range when we are in our 40s and 50s.
In addition, any increase in blood pressure beyond the normal range is linked to a higher amount of WMH.
This suggests that even slightly elevated blood pressure before it meets the criteria for treating hypertension has a damaging effect on brain tissue.
One author of the study is Dr. Karolina Wartolowska.
The study is published in the European Heart Journal.
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