Summary: A new study reveals middle aged people who experience lightheadedness or dizziness upon standing, as a result of a sudden drop of blood pressure, may face a higher risk of developing dementia as they age.
People who feel faint, dizzy or lightheaded when standing up may be experiencing a sudden drop in blood pressure called orthostatic hypotension. Now a new study says middle-aged people who experience such a drop may have a greater risk of developing dementia or stroke decades later. The study is published in the July 25, 2018, online issue of Neurology.
“Orthostatic hypotension 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,” said study author Andreea Rawlings, PhD, MS, of Johns Hopkins Bloomberg School of Public Health in Baltimore, Md.
For this study, low blood pressure upon standing was defined as a drop of at least 20 millimeters of mercury (mmHg) in systolic blood pressure, which is the pressure in the blood vessels when the heart beats, or at least 10 mmHg in diastolic blood pressure, the pressure when the heart is at rest. Normal blood pressure is less than 120/80 mmHg.
The study involved 11,709 people with an average age of 54 who were followed for an average of 25 years. Participants met with researchers up to five times over the course of the study. None had a history of heart disease or stroke at the beginning of the study.
During the initial exam, participants were screened for orthostatic hypotension. They were instructed to lie down for 20 minutes and then stand up in a smooth, swift motion. Blood pressure was taken five times upon standing. Researchers determined the average of the readings and then calculated the difference from the participant’s average resting blood pressure. Researchers determined that 552 participants, or 4.7 percent, had orthostatic hypotension at the start of the study.
Researchers monitored participants throughout the study for dementia and stroke with study visits and by reviewing medical records. During the study, 1,068 people developed dementia and 842 people had an ischemic stroke, which is a stroke where blood flow is blocked to part of the brain.
Researchers found those who had orthostatic hypotension at the beginning of the study had a 54 percent higher risk of developing dementia than those who did not have orthostatic hypotension at the beginning of the study. A total of 999 of the 11,156 without orthostatic hypotension, or 9 percent, developed dementia, compared to 69 of the 552 people with orthostatic hypotension, or 12.5 percent.
In addition, those with orthostatic hypotension had twice the risk of ischemic stroke. A total of 15.2 percent, or 84 of 552 people, with orthostatic hypotension had an ischemic stroke, compared to 6.8 percent, or 758 of 11,157 people without orthostatic hypotension. There was no association with bleeding strokes.
“Measuring orthostatic hypotension in middle-age may be a new way to identify people who need to be carefully monitored for dementia or stroke,” said Rawlings. “More studies are needed to clarify what may be causing these links as well as to investigate possible prevention strategies.”
A limitation of the study was that orthostatic hypotension was measured only once during the study and may not represent change in blood pressure over time.
Funding: The study was funded by the National Heart, Lung and Blood Institute, the National Institutes of Health and the National Institute of Diabetes and Digestive and Kidney Diseases.
Source: Renee Tessman – AAN
Publisher: Organized by NeuroscienceNews.com.
Image Source: NeuroscienceNews.com image is in the public domain.
Original Research: Abstract for “Association of orthostatic hypotension with incident dementia, stroke, and cognitive decline” by Andreea M. Rawlings, Stephen P. Juraschek, Gerardo Heiss, Timothy Hughes, Michelle L. Meyer, Elizabeth Selvin, A. Richey Sharrett, B. Gwen Windham, Rebecca F. Gottesman in Neurology. Published July 25 2018.
Association of orthostatic hypotension with incident dementia, stroke, and cognitive decline
To examine associations of orthostatic hypotension (OH) with dementia and long-term cognitive decline and to update previously published results in the same cohort for stroke with an additional 16 years of follow-up.
We analyzed data from 11,709 participants without a history of coronary heart disease or stroke who attended the baseline examination (1987–1989) of the prospective Atherosclerosis Risk in Communities (ARIC) study. OH was defined as a drop in systolic blood pressure (BP) of at least 20 mm Hg or a drop in diastolic BP of at least 10 mm Hg on standing. Dementia was ascertained via examination, contact with participants or their proxy, or medical record surveillance. Ischemic stroke was ascertained via cohort surveillance of hospitalizations, cohort follow-up, and linkage with registries. Both outcomes were adjudicated. Cognitive function was ascertained via 3 neuropsychological tests administered in 1990 to 1992 and 1996 to 1998 and a full battery of tests in 2011 to 2013. Scores were summarized and reported as SDs. We used adjusted Cox regression and linear mixed models.
Over ≈25 years, 1,068 participants developed dementia and 842 had an ischemic stroke. Compared to persons without OH at baseline, those with OH had a higher risk of dementia (hazard ratio [HR] 1.54, 95% confidence interval [CI] 1.20–1.97) and ischemic stroke (HR 2.08, 95% CI 1.65–2.62). Persons with OH had greater, although nonsignificant, cognitive decline over 20 years (SD 0.09, 95% CI −0.02 to 0.21).
OH assessed in midlife was independently associated with incident dementia and ischemic stroke. Additional studies are needed to elucidate potential mechanisms for these associations and possible applications for prevention.