Scientists have long been aware of a worrying link between high blood pressure and the onset of dementia.
But now, in a new study published in the European Heart Journal, researchers have mapped how high blood pressure affects specific regions of the brain, unearthing the best evidence yet that the two conditions are indeed connected.
In fact, high blood pressure may even be a direct cause of brain dysfunction, they suggest.
"Our study has, for the first time, identified specific places in the brain that are potentially causally associated with high blood pressure and cognitive impairment," said study lead author Mateusz Siedlinski, a researcher at the Jagiellonian University Medical College, in a press release.
Siedlinski and his team parsed through MRI brain scans paired with genetic data from over 30,000 patients in the UK Biobank medical database.
By using Mendelian randomization, a technique that eliminates confounding factors by focusing on genes that could predispose a person to certain conditions, the team found that nine parts of the brain exhibited changes related to both higher blood pressures and a decline in cognitive function.
To eliminate any room for doubt, the researchers then double-checked their findings with a separate batch of patients in Italy.
"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," explained study co-author Tomasz Guzik, a professor of cardiovascular medicine at the University of Edinburgh, in the release.
There is one nagging caveat, though: since most of the participants were white and middle-aged, the researchers note that it "might not be possible to extrapolate the findings to older people," according to the statement.
Nevertheless, of the parts they observed to be affected, the putamen and the anterior thalamic radiation were the most notable. The putamen, located in the front of the brain, is responsible for controlling movement and facilitating learning, while the latter is in charge of executive functions like planning tasks. Various regions of white matter, the tissue responsible for connecting different parts of the brain, were also found to be affected.
The researchers estimate that around 30 percent of the global population suffers from high blood pressure, which, based on their findings, puts a hefty helping of us at risk of dementia.
Troubling a find as it may be, it's no doubt a welcome clue in treating the condition, especially since the cause of its most devastating form, Alzheimer's disease, remains largely unknown.
"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," said co-author Joanna Wardlaw, a neuroscientist at the University of Edinburgh, in the release.
"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 future," she added.
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