Scientists researching potential links between high blood pressure and dementia appear to have made a breakthrough.
Regions of the brain affected by high blood pressure which leads to cognitive decline and dementia have been identified for the first time. A team of researchers used MRI scans of brains, genetic analyses and data from thousands of patients to investigate the effect of high blood pressure on the brain.
They found specific regions of the brain - including those linked to memory loss and thinking skills - that are especially affected. Though previous studies have shown that high blood pressure negatively impacts the brain, this is the first study to ever show precisely which areas are most affected.
The international study hopes to inform scientists and doctors in developing new methods to treat cognitive impairment in those with high blood pressure and predict those most at risk of developing dementia. The study group, led by Professor Tomasz Guzik, of both the University of Edinburgh and the Jagiellonian University Medical College in Krakow, Poland, gathered information from a combination of sources.
The researchers looked at MRI scans of brains as well as genetic analyses and observational data from thousands of patients to decipher the effects of high blood pressure on cognitive function. They also checked their findings alongside a large, separate group of patients in Italy.
High blood pressure is such a common malady that it affects an estimated 30 per cent of the worldwide population - with another 30 per cent showing early signs of the disease. Several studies have demonstrated how it can affect the ways in which our brains work and even cause long-term changes.
However, until now, it was not known exactly how high blood pressure damages the brain, nor which specific regions are affected.
In this groundbreaking study, co-funded by the European Research Council, the British Heart Foundation and the Italian Ministry of Health, Prof. Guzik and his team analysed MRI imaging of more than 30,000 patients in the UK Biobank study. They also looked at genetic information from genome-wide association studies (GWAS) from three international groups and a technique called 'Mendelian randomisation' to see if high blood pressure was actually the root cause of changes to specific parts of the brain, as opposed to merely being associated with the changes.
On how Mendelian randomisation works, Prof. Guzik explained: "It's is a way of using genetic information to understand how one thing affects another. In particular, it tests if something is potentially causing a certain effect, or if the effect is just a coincidence.
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"It works by using a person's genetic information to see if there is a relationship between genes predisposing to higher blood pressure and outcomes. If there is a relationship, then it is more likely that the high blood pressure is causing the outcome.
"This is because genes are randomly passed down from parents, so they are not influenced by other factors that could confuse the results. 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."
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