Orthostatic hypotension may be a risk factor for dementia.
Some people feel a lightheaded sensation when standing up. This is referred to as orthostatic hypotension.
As we get to our feet, gravity causes blood to pool in the large vessels of the lower body, causing a sudden drop in blood pressure. Normally, the nervous system orchestrates a response to counteract this, increasing heart rate and constricting blood vessels.
However, in some people, this mechanism does not work properly, or it works too slowly, leading to a reduction of blood in the brain and therefore a sensation of dizziness.
Recently, researchers from Johns Hopkins Bloomberg School of Public Health in Baltimore, MD, decided to look at orthostatic hypotension in more detail. They wanted to understand whether it might be a useful predictor of future health.
Orthostatic hypotension as a risk factor
Study author Andreea Rawlings, Ph.D., explains the reasons why they embarked on the study. "Orthostatic hypotension," she says, "has been linked to heart disease, fainting, and falls, so we wanted to conduct a large study to determine if this form of low blood pressure was also linked to problems in the brain, specifically dementia."
To open this question up, they had access to data from 11,709 people, aged 54, on average. None of the participants had a history of stroke or heart disease at the start of the study. They were followed for 25 years, and across that period they met up with the researchers around five times.
During their first visit, participants were tested for orthostatic hypotension. They lay down for 20 minutes before being asked to stand up quickly but smoothly. After standing, their blood pressure was taken five times. In total, 4.7 percent of the participants were defined as having orthostatic hypotension.
Over the following 25 years, 1,068 people developed dementia and 842 experienced an ischemic stroke, which occurs when blood flow is blocked to an area of the brain.
Of the 11,156 without orthostatic hypotension, 999 developed dementia (9 percent), and of the 552 people with orthostatic hypotension, 69 developed dementia (12.5 percent).
So, overall, individuals who had orthostatic hypotension at the beginning of the study had a 54 percent higher risk of developing dementia than those who did not.
They also found that people with orthostatic hypotension had double the risk of ischemic stroke: 15.2 percent, compared with 6.8 percent of those without orthostatic hypotension.
"Measuring orthostatic hypotension in middle-age may be a new way to identify people who need to be carefully monitored for dementia or stroke. More studies are needed to clarify what may be causing these links as well as to investigate possible prevention strategies."
Andreea Rawlings, Ph.D.
The findings, published this week in the journal Neurology, are likely to spark further investigation.
However, the study does have some limitations. For instance, orthostatic hypotension was only tested at the start of the study, and an individual's blood pressure might change dramatically over the course of decades.
Although more research is needed, this symptom could eventually be used as an early warning system for those with an increased risk of dementia.