For the new study, scientists used the largest collection of brain scans from UK Biobank and analysed data from over 31,500 people in DPUK’s Data Portal. The Data Portal contains health research records from over 3.5m people and provides a safe platform to study them.
The data analysed in this research was from people who had undergone a brain scan and completed a variety of tests of thinking skills called cognitive tests. People without hypertension (referred to scientifically as normotensive) were also included and were used as a control group for comparison.
Dr Danielle Newby from Oxford University, who led the research using funding from her DPUK Discovery Award, said: ‘Our work is unique in that it is the most extensive study of its kind to look at both brain imaging and cognitive tests while measuring hypertension rigorously in several different ways.’
Investigating the possible health implications of having hypertension is crucial because 31.1% of adults worldwide have high blood pressure – over a billion people. Plus, this figure is likely to rise due to the ageing population.
The method by which Dr Newby and colleagues identified hypertension was through a combination of their blood pressure measurements, current medications, and medical history. The 17,000 people who had hypertension were split into those who described themselves as having high blood pressure, and those who did not. This was to check for the effects of undiagnosed hypertension.
The researchers found people with hypertension had reduced brain volume compared to normotensive people in the majority of brain areas studied. Interestingly, one of the areas not affected by hypertension was the amygdala, the brain’s emotion-processing centre that is not usually damaged by dementia. Learn more about different regions of the brain in this blog post.
Hypertensive patients also performed more poorly on cognitive tests like verbal and numerical reasoning tasks, however the results were not consistent between different tasks. This means thinking skills could be somewhat impaired in hypertensive patients compared to normotensive people. People with dementia also have smaller brain volumes and generally do worse in cognitive tests than healthy controls, suggesting there could be some underlying relationship between hypertension and dementia.
The biggest differences were seen between normotensive people and people who self-reported that they had hypertension. The team also investigated the effect of length of time patients had lived with hypertension.
Dr Newby said: ‘The effect of duration of hypertension on cognitive ability was less clear, reflecting the need for more research in this area. I am now planning to investigate whether anti-hypertensive drugs could be used to reduce dementia risk, given the similar pattern of brain damage and loss of thinking skills.’
Repurposing medicines that are currently used to treat other diseases is an exciting new area of dementia research. Keep an eye on our news section for the latest developments in this area.
The paper was published in the Journal of Alzheimer’s Disease and was also funded by the Medical Research Council, Janssen Pharmaceuticals, and the EU’s Horizon 2020 programme.