Elevated blood pressure was tied to lower gray matter volume in young adults, researchers reported.
Gray matter volumes in 20- to 30-year olds decreased as blood pressure increased, with changes occurring in the same brain regions seen in previous studies of older people with hypertension, reported Arno Villringer, MD, of the Max Planck Institute for Human Cognitive and Brain Sciences in Leipzig, Germany, and colleagues in Neurology.
“Previously, brain damage related to hypertension has been assumed to result over years of blood pressure elevation, but our study suggests that subtle decreases in the brain’s gray matter volume can be seen in young adults between 20 and 40 years of age, who have never been diagnosed with hypertension, and who have blood pressure only slightly above 120/80 mm Hg,” Villringer told MedPage Today.
“While the study shows correlational relationships between above-normal blood pressure and lower gray matter volumes, we did not yet uncover a causal link which proves that higher blood pressure causes the observed brain alterations,” he added.
The findings add to previous research tying blood pressure to brain changes, noted Rafael Llinas, MD, of Johns Hopkins Bayview Medical Center in Baltimore, who was not involved with the study.
“There already have been papers that show high blood pressure reduces the grey matter of the brain and affects the deeper white matter, which are risk factors for dementia in older patients,” Llinas told MedPage Today. “There is evidence that your health at middle age predicts brain health as you age. But this is one of the first studies that show changes in the brain can occur even in young age — and that hypertension may not be a disorder that harms over time, but may need to be screened for and treated much earlier than people expected.”
In the study, Villringer and co-authors analyzed structural 3T T1-weighted MRIs of 423 healthy young adults (mean age 27.7 years) who had not previously been diagnosed with hypertension. MRI data originated from four unpublished cross-sectional studies in Leipzig from 2010 to 2015. The researchers performed voxel-based morphometry on each study separately and combined results in image-based meta-analyses.
All participants had at least one blood pressure reading: 41% had blood pressure lower than 120/80 mm Hg (defined as normal); 29% had blood pressure between 120/80 to 129/84; 19% between 130/85 and 139/89; and 11% above 140/90 (defined as hypertension in the study, but which is now stage II hypertension in U.S. guidelines).
The meta-analyses showed that, across a range of blood pressures above 120/80 mm Hg, gray matter alterations emerged continuously in the hippocampus, amygdala, thalamus, frontal, and parietal structures. Differences in gray matter volume were even evident between people with blood pressure less than 120/80 and those with the next two levels of elevated blood pressure.
Gray matter volume differences between participants in the highest versus the lowest blood pressure categories totaled 581 voxels (voxel size=2x2x2 mm3), with the biggest variance in the left inferior frontal gyrus (107 voxels).
“As we debate whether to treat systolic blood pressure in the 120-130 mm Hg range, a new study has found that a blood pressure greater than 120/80 mm Hg in young adults aged 19 to 40 was associated with reduced gray matter volume not only in cortical areas — frontal, parietal, and hippocampal-temporal areas — but also in subcortical structures, thalamus and amygdala,” observed Gayatri Devi, MD, MS, of Lenox Hill Hospital in New York City, who also was not part of the study.
These regions are affected clinically and pathologically in neurodegenerative disorders like Alzheimer’s disease, and hypertension is a well known risk factor for dementia, Devi added.
“Vascular and neurologic health are intricately intertwined and better control of hypertension as early in life as possible is one key way to reduce risk for brain disease later in life,” she told MedPage Today.
The fact that associations were found in young people “suggests that blood pressure management should be taken seriously early on and that even being ‘prehypertensive’ can have a long-term impact on the development of neurological diseases such as dementia and stroke,” added Sun Kim, MD, of NYU Langone Hospital in New York City. “It will be interesting to see if longitudinal data can be collected and correlated with the actual development of these diseases and others.”
The study was limited by its cross-sectional design, Villringer and colleagues noted: It could not assess causality between blood pressure and potential brain damage. The four study samples used in the analysis differed in recruitment and data collection; in one sample, blood pressure measurements were recorded only once. And the study included only gray matter measures, so the researchers could not assess the mediating effects of white matter injury on gray matter volume differences, they added.
The study was supported by Max Planck Institute for Human Cognitive and Brain Sciences.
The authors reported no relevant relationships with industry.