Hypertensive Disorders in Pregnancy Linked to Dementia Later in Life

Pregnant women with gestational hypertension and preeclampsia/eclampsia had a higher risk for vascular dementia later in life, though they showed no significant excess risk for Alzheimer's disease, according to a study that retrospectively tracked women over an 80-year period.

Among nearly 20,000 women with a history of hypertensive disorders of pregnancy (HDP), risk for vascular dementia was higher in those with preeclampsia/eclampsia (HR 1.58, 95% CI 1.11-2.24, P=0.011) and those with gestational hypertension (HR 2.75, 95% CI 0.90-8.40, P=0.077) compared with those without HDP, reported Karen Schliep, PhD, MSPH, of the University of Utah School of Medicine in Salt Lake City, during the Alzheimer's Association International Conference.

The risk for all-cause dementia was also higher with these conditions (HR 1.38, 95% CI 1.26-1.50 and HR 1.36. 95% CI 1.03-1.79, respectively).

As much as 61% of the excess risk could be explained by midlife heart and mental disorders, Schliep told MedPage Today. "These include myocardial infarction, ischemic heart disease, heart failure, stroke, chronic kidney disease, diabetes, hypertension, and depression. This is important information as it points to where we can intervene to potentially prevent dementia or at least delay it."

Those with preeclampsia/eclampsia were also more likely to develop other/unspecified dementias (HR 1.51, 95% CI 1.36-1.68, P<0.001) compared with women without HDP, but the excess risk for those with gestational hypertension didn't reach statistical significance (HR 1.31, 95% CI 0.96-1.80, P=0.093).

After controlling for factors such as mother's age at first indexed birth, the researchers found no significant link between any type of HDP and Alzheimer's disease (P=0.70 for preeclampsia/eclampsia and P=0.691 for gestational hypertension). This may be because Alzheimer's and other dementias have different pathophysiologies, Schliep said.

Chris Weber, PhD, director of global science initiatives for the Alzheimer's Association, told MedPage Today that "these new data illuminate the importance of prenatal care and monitoring the long-term health of pregnant people as it may impact cognition and dementia risk in later life. Those who experience changes with their memory and cognition should have a discussion with their healthcare provider."

Previous studies on the effects of HDP on dementia risk have had conflicting results, Schliep noted. "These inconsistencies may arise from limitations of study designs, notably lack of sufficiently powered, population-based cohort studies and failure to account for important confounding or mediating factors."

It's not clear why HDP may be linked to dementia later in life. Schliep said she's working with her colleagues on prospective studies to determine whether HDP exposes underlying risk for cardiovascular and neurological diseases or whether "the HDP harms the mother in some way, leaving her vulnerable to cardiovascular disease or dementia in later life."

For now, she noted, "all clinicians can partner with patients to mitigate long-term risks after pregnancy complications like HDP by routinely asking all currently or previously pregnant women about pregnancy complications they may have had, [as well as] any postpartum complications."

"Half of women do not receive recommended postpartum care after delivery or receive annual primary care visits. There are preventive measures that can mitigate cardiovascular disease and dementia risks for women with a history of HDP and other pregnancy complications, including exercise, weight control, smoking prevention and cessation, and early identification and treatment for elevated lipids, high blood pressure, and diabetes," she added.

For this study, Schliep and colleagues tracked women who gave birth in Utah from 1939 to 2019. Women with HDP (n=19,989) were matched 1:2 to women who didn't have HDP (n=39,679).

The groups had similar mean ages (29), and 5% to 6% were not white. Hispanics made up 9% to 10% of the groups, and 22% of the HDP group were college graduates or higher compared with 26% in the non-HDP group.

Among those with HDP, 3.5% had eclampsia, 62% had preeclampsia, and 34% had gestational hypertension.

Looking at data from 1979 to 2019, the researchers found that 4% of the patients developed dementia. Schliep said this number is likely to be low because some cases were not diagnosed. Of those, 24% had Alzheimer's disease, 70% had other/unspecified, and 6% had vascular dementia.

"These findings are in line with the largest study to date of over 1 million women that was conducted in Denmark," Schliep said. "While these findings remained robust after further considering the confounding or moderating influence of race and ethnicity, further research in more representative populations is needed given that our study was made up of only 9% Hispanic and 5% non-white women."

The Danish study, which tracked 1.18 million women, linked preeclampsia to a 3.46-fold increase in vascular dementia (95% CI 1.97-6.10), but found only a modest link to Alzheimer's disease.

"In future research," Schliep said, "we would like to investigate pre-pregnancy blood pressure and other cardiometabolic biomarkers -- e.g., lipid panels -- to better answer this question as to how much harm the actual pregnancy complication causes. This will help clinicians and researchers better understand key time points for intervention."

Comment