People with high blood pressure face a greater risk of developing dementia, according to a new study in published in the journal Cardiovascular Research.
The study is also the first to show how new uses of magnetic resonance imaging (MRI) can detect very early signs of neurological damage in people with high blood pressure, before any symptoms of dementia occur.
High blood pressure, or hypertension, is a chronic condition that leads to progressive organ damage. Research has shown that most cases of Alzheimer’s disease and dementia are not due to genetic predisposition but rather to chronic exposure to vascular risk factors.
Treatment of dementia patients usually begins only after symptoms are clearly evident, even though it has become increasingly clear that when signs of brain damage are manifest, it may be too late to reverse the neurodegenerative process. Physicians still lack methods for assessing progression markers that could detect pre-symptomatic changes and identify patients at risk of developing dementia.
“The problem is that neurological alterations related to hypertension are usually diagnosed only when the cognitive deficit becomes evident, or when traditional magnetic resonance shows clear signs of brain damage. In both cases, it is often too late to stop the pathological process,” said Dr. Giuseppe Lembo, the coordinator of this study. Lembo is professor of applied medical technology at the Department of Molecular Medicine of Sapienza University of Rome.
For the study, researchers screened subjects who had been admitted to the Scientific Institute for Research, Hospitalization and Health Care (IRCCS), Neuromed, in Italy. Chosen participants, aged 40 to 65, gave written consent to be part of the study.
Participants showed no signs of structural damage and no diagnosis of dementia. All patients were given clinical exams to determine their hypertensive status and the related organ damage. Patients also had an MRI scan to identify microstructural damage.
The researchers looked for any brain changes in the white matter microstructure. The findings show that hypertensive patients have significant alterations in three specific white matter fiber-tracts. Hypertensive patients also scored significantly worse in the cognitive domains linked to brain regions connected through those fiber-tracts, showing decreased performances in executive functions, processing speed, memory and related learning tasks.
Overall, white matter fiber-tracking on MRIs showed an early signature of damage in hypertensive patients when otherwise undetectable by conventional neuroimaging.
As these changes can be seen before patients show symptoms, they could be given medication earlier to prevent further deterioration in brain function. These findings are also widely applicable to other forms of neurovascular disease, where early intervention could be of significant therapeutic benefit.
“We have been able to see that, in the hypertensive subjects, there was a deterioration of white matter fibers connecting brain areas typically involved in attention, emotions and memory,” said Lorenzo Carnevale, first author of the study.
“An important aspect to consider is that all the patients studied did not show clinical signs of dementia and, in conventional neuroimaging, they showed no signs of cerebral damage. Of course, further studies will be necessary, but we think that the use of tractography will lead to the early identification of people at risk of dementia, allowing timely therapeutic interventions.”
Source: Oxford University Press USA