Young adults with blood pressure (BP) above normal, but not yet defined as high blood pressure, are more likely to experience brain shrinkage than those with normal blood pressure. These are the results of a study published online in Neurology on January 23.
Studies have demonstrated an association between high BP in midlife and the risk for late-life cognitive decline, including late-onset Alzheimer's disease.
Other studies that looked at specific brain structures found a link between high BP and reductions in brain volume in the areas of the brain important for memory processing and cognitive skills.
Elevated BP in midlife also has been linked to lower brain weight on autopsy and more tangles and plaques associated with Alzheimer’s disease in the hippocampus, a region involved in memory.
But, the effects of elevated BP on the brains of people younger than 40 are unclear.
To find out if modestly elevated BP levels correlated with brain shrinkage in young adults, researchers identified 423 participants—24 percent of whom were women, whose average age was 28, and none had been previously diagnosed with high BP—from larger studies conducted in Germany between 2010 and 2015.
The researchers measured systolic blood pressure, the pressure in the blood vessels when the heart beats, and diastolic blood pressure, the pressure in the blood when the heart is at rest, at varying times of day. They then took the average of these multiple measurements to find the average systolic and diastolic reading for each participant.
Using the 2013 European guidelines for managing high BP, the researchers classified participants in one of four categories: category 1 was for those whose BP was below 120/80, which was defined as normal; category 2 was for those with BP between 120/80 and 129/84; category 3 was for those with BP between 130/85 and 139/89; and category 4 was for those with BP greater than or equal to 140/90, which was defined as high. Forty-one percent of participants were in category 1, 29 percent were in category 2, 19 percent in category 3, and 11 percent in category 4.
The researchers used a mapping technique to detect differences between volumes in brain regions on MRI scans.
Participants with BP above normal—even just one category above normal—showed lower gray matter volume, which contains most of the brain's neurons essential for a wide range of functions, such as muscle control and sensory perception. Areas affected by low gray matter volume include the frontal and parietal lobes, the hippocampus, which is involved in memory, the amygdala which processes emotions, and the thalamus, which plays a role in sensory signaling and motor skills, among other functions.
No significant associations were identified between elevated blood pressure and total brain size.
Typically, loss of gray matter is seen in older adults. But, according to the researchers, the current findings suggest that maintaining lower blood pressure in early adulthood might be essential for preventing brain diseases, such as Alzheimer's, as people get older.
Read more about the dangers of high blood pressure in How Late-Life Blood Pressure Affects Brain Health and Control Your Blood Pressure, Save Your Brain. For ways to keep your blood pressure in check, read 6 Questions About Blood Pressure.
