The findings from the Insight 46 study are published in The Lancet Neurology.

“The findings show that blood pressure monitoring and interventions aimed at maximising brain health later in life need to be targeted at least by early midlife,” said the study’s lead author, Professor Jonathan Schott (UCL Queen Square Institute of Neurology).

Insight 46 is a neuroscience sub-study of the MRC National Survey of Health and Development (NSHD), the longest running birth cohort in the UK. Based at the MRC Unit for Lifelong Health and Ageing at UCL, Insight 46 is designed to follow over 500 birth cohort members to look for early signs and risk factors for dementia as they reach their 70s.

The new study, funded by Alzheimer’s Research UK, MRC Dementias Platform UK, Wellcome, Brain Research UK, the Wolfson Foundation and the Weston Brain Institute, allows for a unique perspective on the risk factors throughout life that impact brain health at the age of 70.

Blood pressure in midlife has previously been linked to a higher risk of dementia but the mechanism by which this happens, and the time when blood pressure is most important, remain to be fully understood.

To answer these questions, the research team followed 502 individuals from the NSHD, who were all born in the same week in 1946. The participants were free from dementia at the start of the study and 465 underwent brain scans to assess their brain health. Due to the nature of the birth cohort, the researchers were able to measure their blood pressure at 36, 43, 53, 60-64 and 69 years.

The brain scans looked for levels of a key Alzheimer’s protein, amyloid, in the brain. The scans also assessed the size of the brain – an indicator of brain health – and the presence of blood vessel damage in the brain.

The results showed that higher blood pressure at the age of 53 and faster rises in blood pressure between 43 and 53 were associated with more signs of blood vessel damage or ‘mini strokes’ in the brain when an individual was in their early 70s.

Higher blood pressure at the age of 43 and greater increases in blood pressure between the ages of 36 and 43 were associated with smaller brain volumes.

Blood pressure was not associated with the amount of amyloid protein in the brain and did not appear to predict memory and thinking problems at this age.

“We now know that damage caused by high blood pressure is unlikely to be driven through the hallmark Alzheimer’s protein amyloid, but through changes in blood vessels and the brain’s architecture,” said Professor Schott.
“This unique group of individuals, who have contributed to research their entire lives, has already shaped our understanding of the factors influencing health throughout life. The Insight 46 study has allowed us to reveal more about the complex relationship between blood pressure and brain health.”
“The findings suggest that blood pressure even in our 30s could have a knock-on effect on brain health four decades later,” he said.
Co-author Dr Josephine Barnes (UCL Queen Square Institute of Neurology) said: “Our study design provides a unique opportunity to examine blood pressure at different ages, blood pressure changes during specific periods from early adulthood to late life, and to explore their influences on brain pathologies and brain volumes. As increases in blood pressure and higher blood pressure between the ages of 36 and 53 seem to have a detrimental effect on brain health in later life, these findings reinforce the need for monitoring blood pressure even before mid-life.”
Dr Carol Routledge, Director of Research at Alzheimer’s Research UK, said: “High blood pressure in midlife is one of the strongest lifestyle risk factors for dementia, and one that is in our control to easily monitor and manage. Research is already suggesting that more aggressive treatment of high blood pressure in recent years could be improving the brain health of today’s older generations. We must continue to build on this insight by detecting and managing high blood pressure even for those in early midlife.”

The Insight 46 study will continue to monitor these participants in the years to come to explore whether those with worse brain health are more prone to cognitive decline and dementia.

The study was completed with support from the National Institute for Health Research University College London Hospitals Biomedical Research Centre.

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