A leading cause of preterm birth, preeclampsia is an inflammatory blood vessel disorder that occurs in 2 per cent to 10 per cent of pregnancies, usually after 20 weeks’ gestation. In addition to high blood pressure, the condition can cause abnormally high levels of protein in the urine and fluid retention.
Based on records for more than 1 million women in Denmark, researchers found the greatest increased risk for women with a history of preeclampsia was for developing so-called vascular dementia, which is thought to be caused by a series of small strokes or impaired blood supply to the brain.
Past studies have already linked preeclampsia to cognitive impairment and brain changes within a year of the pregnancy, the study team notes in The BMJ. Women who experience preeclampsia are also at higher risk of later heart disease, stroke, high blood pressure and diabetes, they add.
“We have accumulated enough evidence that the effects of preeclampsia on a woman’s health are not confined to pregnancy,” said the study’s senior author Heather Boyd of Statens Serum Insitut in Copenhagen.
“We now know that preeclampsia should be seen as a marker for increased risk of vascular morbidity later in life. And awareness of this is improving – in their latest guidelines, both the American Heart Association and the European Society of Cardiology include statements about considering a history of pregnancy complications when evaluating a woman’s risk of cardiovascular disease,” Boyd said.
To examine links between preeclampsia and dementia, the researchers used national registry data to identify 1,178,005 women who had given birth in Denmark between 1978 and 2015, just over 4 per cent of whom experienced preeclampsia during one or more pregnancies.
Women were followed for an average of 21 years. Even after adjusting for other factors that could influence dementia risk, including heart disease and diabetes, researchers found the risk for late-onset (after age 65) vascular dementia was 6.5 times higher among those with a history of preeclampsia.
Women with a preeclampsia history had about twice the risk of early-onset dementia compared with no history.
They also had a 50 per cent higher risk of developing Alzheimer’s disease and a 40 per cent higher risk of other, non-specific dementias.
A history of recurrent preeclampsia in more than one pregnancy was even more strongly associated with dementia than when it occurred in just a single pregnancy.
“We still don’t know how to identify the women with a history of preeclampsia who are at greatest risk of cardiovascular disease,” Boyd noted.
“Asking cardiologists to see all women with a history of preeclampsia at regular intervals for the rest of their lives would be overkill and would rapidly swamp the healthcare system,” he added.
She recommends that women who have had severe preeclampsia, especially early-onset preeclampsia or preeclampsia with vascular complications, should at least have regular follow-up by their internists.
“I certainly think that all women who have had preeclampsia need to have good primary care,” said Dr Eliza Miller, a neurologist at Columbia University Irving Medical Center in New York City, who wasn’t involved in the study.
“Doctors need to be aware that preeclampsia is a really important part of a woman’s medical history and it’s something that all doctors should ask their women patients about even though we don’t really know yet if there is a specific intervention we should be doing, such as putting women on a baby aspirin early on or cholesterol medications,” she said in a phone interview.
In an accompanying editorial, Dr Joel Ray of the University of Toronto writes that the study “enables us to frame vascular dementia as a stroke-like condition, with cognitive impairment being a dominant manifestation. It follows, then, that vascular dementia might be preventable in women with previous preeclampsia, with good control of blood pressure, lipids, and glucose.”
“What we need to figure out now is, does preeclampsia itself cause vascular damage on a scale great enough to have lifelong consequences? Or does having preeclampsia signal an underlying predisposition to vascular dysfunction,” Boyd said.