Feeling faint, dizzy, or lightheaded after standing up, known as orthostatic hypotension (OH), was associated with an increased risk of dementia among middle-aged people, according to a study published online in Neurology on July 25. As they aged, those with orthostatic hypotension in midlife were more likely to develop dementia and ischemic stroke than those without the condition.
Standing up leads to a drop in blood pressure as gravity causes blood to pool in the legs and abdomen. Normally, the nervous system counteracts this by raising the heart rate and narrowing the blood vessels to increase blood pressure. However, in OH, something hinders the body's ability to counteract low blood pressure, which leads to less blood flow to the brain and more dizzy spells.
Repeated drops of blood pressure can result in insufficient blood flow to the brain. This can manifest as dizziness, fatigue, and weakness upon standing.
Previous studies have examined the potential link between orthostatic hypotension (OH) and cognitive decline and dementia, but results have been skewed due to small sample sizes, limited follow-up, or the age at which OH was revealed.
To examine the link further, a team of researchers at the Johns Hopkins Bloomberg School of Public Health in Baltimore, analyzed data from 11,709 participants, aged 54, recruited between 1987 and 1989 in the Atherosclerosis Risk in Communities (ARIC) study. At the start of the study, participants did not have a history of stroke or heart disease. On average, they were followed for 25 years, and met with researchers up to five times throughout the study.
During the first visit, the team tested participants for OH by asking them to lie down for at least 20 minutes before standing up. Upon standing, the researchers took their blood pressure five times. The researchers defined OH as a drop in systolic blood pressure of at least 20 mm Hg or a drop in diastolic blood pressure of at least 10 mm HG on standing.
Study visit examinations, contact with participants or proxies, and medical record reviews helped researchers identify cases of dementia. They used hospitalization records, follow-up, and links with registries to identify cases of ischemic stroke. Cognitive testing was administered during visits two, four, and five.
Of 11,709 participants, 552 had OH at baseline. Throughout the study, 1,068 people developed dementia and 842 people had an ischemic stroke. People with OH were one and a half times more likely to develop dementia than those without OH. In addition, those with OH had twice the risk of stroke than those without the condition. Over the study period, people with OH also experienced cognitive decline, but the researchers deemed it insignificant.
Can Orthostatic Hypotension Predict Cognitive Impairment?
The researchers concluded measuring orthostatic hypotension in middle-age may serve as an indicator for monitoring these patients for risk of stroke and dementia.
"The presence of orthostasis, especially in midlife, might identify individuals in whom more careful monitoring or risk factor management might be warranted," the researchers wrote.
However, they added, more studies are needed to clarify what's driving the association between orthostatic hypotension and cognitive impairment, and what prevention strategies could be implemented.