Pre-eclampsia may raise risk of dementia, study finds

Pre-eclampsia may raise the risk of dementia later in life, a trio of studies suggested today.

One set of researchers from Minnesota found women who suffer the condition end up having more toxic clumps in their blood, a hallmark sign of Alzheimer’s. 

A separate University of Utah study showed those with high blood pressure — which happens in pre-eclampsia — during pregnancy had a 64 per cent higher risk of going on to develop vascular dementia.

Meanwhile, a Dutch study suggested expectant mothers who suffered hypertension saw their brain tissue wear away 38 per cent more than those without pre-eclampsia or high blood pressure.

Kim Kardashian and Beyonce both suffered from pre-eclampsia, which is thought to affect around 5 per cent of pregnancies in Britain and the US.

It causes expectant mothers to suffer high blood pressure, which previous research has shown can lead to heart disease later in life.

Pre-eclampsia is not the only condition to cause high blood pressure in expectant mothers, however, with gestational hypertension also contributing to it in some women.

Dr Rosa Sancho, head of research from Alzheimer’s Research UK, said: ‘This series of findings highlights how important it is that pregnant women are offered regular monitoring and treatment of high blood pressure during their pregnancy.

‘Women are at a higher risk of dementia than men, even when women’s longer lives are taken into account. 

‘Researchers have proposed different theories to explain women’s elevated risk of dementia, but there’s more work to do to find conclusive answers including research into the factors that can particularly affect women’s cognitive health. 

‘High blood pressure is a risk factor for poor heart health, which has a knock-on effect on our brain health. 

‘This new research highlights the impact that high blood pressure and related disorders during pregnancy can have on women’s risk of developing dementia later in life.’

Previous studies have shown high blood pressure in mid-life can lead to dementia by causing the walls of arteries to the brain to become thicker and stiffer, reducing blood flow to the organ. 

The latest research, by the Mayo Clinic, was presented as an abstract at the Alzheimer’s Association International Conference (AAIC) 2022 in San Diego today.

Researchers took samples from vesicles — small fluid-filled pouches released from brain cells — from 40 women who were healthy during their pregnancies and 40 who had high blood pressure at some point during their term. 

Seven in the latter group suffered severe pre-eclampsia in the 20th weeks of their pregnancies. 

They did not specify exactly how long after the pregnancies they took the samples. 

However, results showed the women who suffered pre-eclampsia had higher levels of amyloid beta in their blood.

A build-up of the protein is considered a hallmark sign of Alzheimer’s, with studies previously suggesting it could even be the cause of the condition.

It builds up to form plaques in the brains of people with the memory-robbing disease. 

The Mayo Clinic study also showed women with pre-eclampsia had higher levels of brain inflammation years down the line.

Brain inflammation is thought to be another potential cause of Alzheimer’s, with previous research linking it to the build up of ‘junk’ proteins in the brain.

Senior author Dr Sonja Suvakov, a biochemist at the Mayo Clinic, suggested the condition could cause a host of ‘neurodegenerative and cognitive risks’.

She said: ‘These findings indicate that women with a history of pre-eclampsia have increased levels of markers of neurovascular damage which may negatively impact their cognitive skills.

‘Further research is required to fully understand the neurodegenerative and cognitive risks that a history of hypertensive disorders confers on women throughout life.’

The researchers have not yet published their full findings, with a full study expected to be released at a later date.

Dr Sancho said: ‘Research to date has shown that women with pre-eclampsia are at a higher risk of heart related diseases such as strokes, as well as cognitive problems.

‘This study builds upon existing knowledge and shows that women with severe pre-eclampsia had markers of brain inflammation, blood vessel damage and higher levels of the hallmark Alzheimer’s protein, amyloid.

‘Although these findings are interesting, we haven’t seen the full data, and more work needs to be done to look at a larger group of women and to unpick the reasons behind these observations.’

The Utah University study was presented at the same conference.

It showed women with pre-eclampsia also had an increased risk of vascular dementia.

The condition is the second most common cause of dementia after Alzheimer’s. 

Researchers tracked the health records of 59,668 elderly women who had given birth when they were younger.

Those who had high blood pressure conditions in pregnancy had a 64 per cent greater risk of developing vascular dementia.

And they were 49 per cent more likely to develop other forms of dementia, but not Alzheimer’s.

Lead author Dr Karen Schliep, an epidemiologist at the university, said: ‘Our results confirm previous findings that pre-eclampsia is most strongly associated with vascular dementia compared to Alzheimer’s or other types of dementia.

‘They further suggest that vascular dementia risk may be just as high for women with a history of gestational hypertension as for preeclampsia.’

Meanwhile, the Erasmus MC Medical Center study linked high blood pressure in pregnancy with increased brain degradation.

The study looked at white matter in 93 women who suffered hypertensive disorders of pregnancy, and 445 who had regular pregnancies.

Researchers scanned their brains 15 years after their pregnancies to see how quickly their tissue had wasted away.

Those who had endured a high blood pressure condition had 38 per cent greater white matter loss — indicating more of their brain had broken down.

Those who had gestational hypertension were more at risk than those suffering pre-eclampsia, however.

Lead author Rowina Hussainali, an epidemiology and obstetrics doctoral student, said: ‘These data clearly indicate that a history of [hypertensive disorders of pregnancy] was associated with more damage to the brain 15 years after pregnancy — damage that could have lasting impacts on cognition.

‘Women with a history of [hypertensive disorders of pregnancy] should be evaluated and treated early for hypertension and other cardiovascular risk factors.’

Pre-eclampsia is thought to be caused by the placenta not developing properly due to a problem with the blood vessels supplying it. 

However, the exact cause isn’t fully understood, the NHS says.

Katherine Gray, research communications manager at Alzheimer’s Society, said: ‘Despite women making up 65 per cent of people living with dementia, relatively little is understood about what’s behind a woman’s dementia risk. 

‘These findings do strengthen what we already know about how high blood pressure affects brain health when women are pregnant.

‘Importantly, the results suggest that if women with a history of blood pressure are identified early and offered the right treatment and support, we could not only keep them healthy during pregnancy and birth, but also potentially reduce their risk of developing dementia later in life.’