Using MRI scans, genetic analyses, and data from thousands of patients the international team of researchers report that they have discovered that certain brain regions particularly suffer due to high blood pressure, particularly those that are connected to memory loss and cognitive abilities. This breakthrough may help in creating new methods for treating blood pressure-related cognitive impairment and identifying those at an increased risk of developing dementia.
“By using this combination of imaging, genetic and observational approaches, we have identified specific parts of the brain that are affected by increases in blood pressure, including areas called the putamen and specific white matter regions. We thought these areas might be where high blood pressure affects cognitive function, such as memory loss, thinking skills and dementia. When we checked our findings by studying a group of patients in Italy who had high blood pressure, we found that the parts of the brain we had identified were indeed affected.
“We hope that our findings may help us to develop new ways to treat cognitive impairment in people with high blood pressure. Studying the genes and proteins in these brain structures could help us understand how high blood pressure affects the brain and causes cognitive problems. Moreover, by looking at these specific regions of the brain, we may be able to predict who will develop memory loss and dementia faster in the context of high blood pressure. This could help with precision medicine, so that we can target more intensive therapies to prevent the development of cognitive impairment in patients most at risk,” says Professor Tomasz Guzik, affiliated with both the University of Edinburgh in Scotland and the Jagiellonian University Medical College in Poland.
Co-funded by the European Research Council, the British Heart Foundation, and the Italian Ministry of Health, this research involved analyzing MRI cans from over 30,000 participants enrolled in the UK Biobank Study, and using genetic information from the Genome-Wide Association Studies (GWAS) of 3 international groups, and using the Mendelian randomization method to determine whether or not high blood pressure could be the root cause of changes to specific brain regions.
“Mendelian randomization is a way of using genetic information to understand how one thing affects another. In our study, if a gene that causes high blood pressure is also linked to certain brain structures and their function, then it suggests that high blood pressure might really be causing brain dysfunction at that location, leading to problems with memory, thinking, and dementia,” explains Guzik.
According to the researchers alterations in 9 brain areas were associated with high blood pressure and worsened cognitive function which includes the putamen, which helps to regulate movement, motor control, learning, cognitive functioning, reward, addiction, and language functions. White matter regions that facilitate brain signaling and transmissions were also affected. Changes in these regions manifested as decreases in brain volume, connections, and activity measures as well as alterations in the brain cortex surface area.
“It has been known for a long time that high blood pressure is a risk factor for cognitive decline, but how high blood pressure damages the brain was not clear. This study shows that specific brain regions are at particularly high risk of blood pressure damage, which may help to identify people at risk of cognitive decline in the earliest stages, and potentially to target therapies more effectively in the future,” adds co-author professor Joanna Wardlaw, Head of Neuroimaging Sciences at the University of Edinburgh.
They highlight one of the study’s findings about systolic and diastolic blood pressure (SBP and DBP). “Perhaps one of the more interesting results in this study is the possible distinct causal effects of SBP vs. DBP. The authors observed some overlapping results for SBP and DBP on cognitive function when analysed in isolation. However, when each parameter is analysed after adjusting for the other, or in multivariable models, intriguing findings begin to emerge. DBP alone does not predict a decline in cognitive function, but in fact, is protective when adjusted for SBP. This result was true both observationally and when using Mendelian randomisation.” They go on to discuss the possible reasons for this.
