Individuals who are diagnosed with high blood pressure at ages 35–44 had smaller brain size and were more likely to develop dementia compared to people who had normal blood pressure, according to a new study (“The Association of Age at Diagnosis of Hypertension With Brain Structure and Incident Dementia in the UK Biobank”) published in Hypertension, an American Heart Association journal.

The results raise the possibility that taking steps in young adulthood to control or delay the onset of high blood pressure may reduce the risk of dementia.

“Little is known about whether the association of hypertension with brain volume and dementia is modified by an individual’s age at their diagnosis of hypertension. Our analysis was based on the U.K. Biobank with baseline data collected between 2006 and 2010. Brain magnetic resonance imaging was used to measure brain volumes between 2014 and 2019,” write the investigators. “

“Dementia was ascertained using hospital inpatient, mortality, and self-reported data until 2021. We randomly selected a control participant for each hypertensive participant stratified by hypertension diagnosis age using propensity score. The cohort comprised 11 399 individuals with hypertension and 11 399 controls for the brain volume analysis and 124 053 individuals with hypertension and 124 053 controls for the dementia analysis. “

Individuals with hypertension diagnosed at ages <35 (β (95% CI, −10.83 [−19.27 to −2.39] mL), 35 to 44 (−6.82 [−12.18 to −1.46] mL), and 45 to 54 years (−3.77 [−6.91 to −0.64] mL) had smaller total brain volume compared with the corresponding controls in the multivariable analysis. Similarly, hypertension diagnosed in early- and mid-life was independently associated with smaller volumes of gray matter, peripheral cortical gray matter, and white matter.

“Over a median follow-up of 11.9 years, 4626 cases of incident all-cause dementia were documented. Individuals with hypertension diagnosed at 35 to 44 years of age only (hazard ratio [95% CI]: 1.61 [1.31–1.99]) had a higher risk of all-cause dementia compared with the corresponding controls after adjustment for covariates.”

Brain scan, MRI scan
Brain MRI. Hypertension diagnosed in young adulthood or mid-life, but not late life is associated with smaller brain volumes and an increased risk of dementia. [PASIEKA/Science Photo Library/Getty Images]

“Hypertension is very common in middle-aged people (45-64 years), and early onset high blood pressure is becoming more common. Although the association among hypertension, brain health and dementia in later life has been well-established, it was unknown how age at onset of hypertension may affect this association. If this is proven, it would provide some important evidence to suggest earlier intervention to delay the onset of hypertension, which may, in turn, be beneficial in preventing dementia,” said Mingguang He, MD, PhD, senior author of the study and professor of ophthalmic epidemiology at the University of Melbourne in Melbourne, Australia.

From the MRI scans, the investigators found:

  • In each diagnostic age category (from 35–54), the total brain volume was smaller in people diagnosed with high blood pressure, and the brain volume of several regions were also smaller compared to the participants who did not have high blood pressure;
  • Hypertension diagnosed before age 35 was associated with the largest reductions in brain volume compared with controls; and
  • Among people with normal blood pressure readings at the time of their MRI scans, those who were previously diagnosed with hypertension at <35 years old had smaller total brain volume compared to people with normal blood pressure who had never been diagnosed with hypertension.

“Individuals who had hypertension diagnosed at younger ages had smaller brain volumes on these one-time measurements. Future research with brain volumes measured at multiple time points could confirm whether hypertension diagnosed at a younger age is associated with a greater decrease in brain volume over time,” said Xianwen Shang, PhD, lead author of the study and a research fellow at the Guangdong Provincial People’s Hospital in Guangzhou, China.

To evaluate dementia, the investigators examined how many participants developed dementia from any cause over a 11.9-year follow-up period, comparing 124,053 people with high blood pressure and 124,053 matched adults who did not have high blood pressure. During the follow-up period (up to 14 years; median of 11.9 years), 4,626 people developed some form of dementia. Analyzing the occurrence of dementia in relation to blood pressure diagnosis, the researchers found:

  • The risk of dementia from any cause was significantly higher (61%) in people diagnosed with high blood pressure between the ages of 35 and 44 compared to participants who did not have high blood pressure.
  • The risk of vascular dementia (a common form of dementia resulting from impaired blood flow to parts of the brain, as might happen after one or more small strokes) was 45% higher in the adults diagnosed with hypertension between ages 45–54 and 69% higher in those diagnosed between ages 35-44, compared to participants of the same age without high blood pressure.
  • Although vascular dementia risk was 80% higher in those diagnosed with high blood pressure before age 35, there were fewer cases of dementia among the younger participants, and the association with high blood pressure was not statistically significant, whereas the risk association was meaningful for individuals ages 45-54 with high blood pressure.
  • In contrast to vascular dementia, no relationship was found between age at hypertension diagnosis and the risk of Alzheimer’s disease, a type of dementia linked to proteins that disrupt brain function.

“Our study’s results provide evidence to suggest an early age at onset of hypertension is associated with the occurrence of dementia and, more importantly, this association is supported by structural changes in brain volume,” noted Shang. The findings raise the possibility that better prevention and control of high blood pressure in early adulthood could help prevent dementia.

“An active screening program to identify individuals with early hypertension and provide earlier, intensive high blood pressure treatment might help reduce the risk of developing dementia in the future,” added He.

In future research, the investigators are planning to examine medical records to detect whether the onset of dementia was preceded by other medical conditions with previously established connections to dementia risk, such as diabetes or stroke, in people who developed high blood pressure during young adulthood or middle age. Results from this study of a predominantly Caucasian population are not necessarily generalizable to people from other racial or ethnic groups.

Previous articleAdvancing Liquid Biopsy Companion Diagnostics with a Novel Sequencing Initiative
Next article2021 Nobel Prize in Medicine Makes Sense: Touch and Temp Discoveries Win