The findings, presented at the American Heart Association’s EPI|LIFESTYLE 2017 Scientific Sessions, come out of a 20-year study into the health of more than 11,000 people.
Low blood pressure, or hypotension, can reduce blood flow to the brain and cause symptoms like dizziness, blurred vision and unsteadiness. Some people may experience hypotension after eating, or when standing for long periods of time. When low blood pressure is brought on by suddenly standing up or changing posture, it is known as orthostatic hypotension.
The researchers in this study worked with 11,503 people who had no history of coronary heart disease or stroke, and had an average age of 54 at the start of the study. At the first visit that took place between 1987 and 1989, the team recorded the blood pressure of the study participants when they stood up after laying down for 20 minutes. Orthostatic hypotension was defined as a drop of 20 mmHg or more in systolic blood pressure, or 10 mmHg or more in diastolic blood pressure. The team found that 703 people, around 6% of study participants, met the criteria for orthostatic hypotension.
The study participants were followed over the next 20 years, and the team found that those who had orthostatic hypertension at the first visit were 40% more likely to develop dementia. The researchers suggest that this indicates that the mechanisms causing orthostatic hypotension persist over time, and that repeated instances of reduced blood flow could result in a lack of oxygen that contributes to damage in the brain.
Dr Laura Phipps, of Alzheimer’s Research UK, said:
“The findings presented today build on evidence showing the important role of the blood supply, not just in contributing to vascular dementia, but potentially playing a role in other forms of dementia too. While many studies have focused on the risks of high blood pressure, these findings suggest that transient low blood pressure could also have a long term impact on the brain. This research adds to a growing and complex picture of how blood pressure changes throughout life can impact the brain. It’s important that researchers build on this emerging area of study to get to the bottom of the mechanisms underlying this risk.
“There is mounting evidence to suggest that what’s good for the heart is good for the brain and maintaining good vascular health is one of the key things people can do to reduce their risk of dementia. As well as maintaining a healthy blood pressure, the best current evidence suggests that not smoking, only drinking in moderation, staying mentally and physically active, eating a balanced diet, and keeping cholesterol levels in check can all help to keep our brains healthy as we age.”