Racial differences for brain bleeds suggest stroke risk greater than thought for blacks

October 06, 2008

Washington, DC − Small, clinically silent areas of bleeding in the brain appear to be more common in black versus white stroke patients hospitalized for new brain bleeds, say researchers at Georgetown University Medical Center. These findings may help explain the higher risk of hemorrhagic stroke among the black population, especially in those who are medically underserved.

So-called "microbleeds" are essentially drops of blood detected by magnetic resonance imaging (MRI) scans of the brain. This study of 87 stroke patients shows that blacks had 32 percent more microbleed than whites, investigators report in the October 7, 2008, issue of Neurology®, the medical journal of the American Academy of Neurology. Black patients were also shown to have microbleeds in multiple areas of the brain more frequently than did white patients.

The researchers say these findings "are not surprising," considering that blacks are between two and three times more likely than other racial groups to suffer from a hemorrhagic stroke, the type of stroke caused by excessive bleeding. This type accounts for only 15 percent of all strokes, and research has shown that microbleeds are found in 50 to 80 percent of hemorrhagic strokes.

"This study suggests that there are significant racial differences in frequency in microbleeds associated with stroke, and we hope this new knowledge will help us better understand underlying risk factors in order to improve treatment and guide stroke prevention," says the study's lead author, Chelsea Kidwell, M.D., professor of neurology and medical director of the Georgetown University Stroke Center.

In addition to race and age, the researchers found that hypertension and alcohol use were associated with microbleed frequency in the patients studied. "Race is the strongest risk factor, and hypertension clearly plays a role," she says. "But other unknown risk factors could also be involved, such as genetic susceptibility."

Kidwell also points out that the black patients who participated in the study were medically underserved, and that this study is the first one to detail the frequency and location of brain microbleeds in this population. Such a study is important, she says, "because it suggests that the burden of this kind of disease in blacks may be even greater than previously believed, and this will help physicians better care for stroke risk factors in this population."

With improved brain scanning technology that can detect tiny iron deposits, scientists have recently discovered these pinpoint drops of blood - smaller than a pen tip - in the brains of people who have had a stroke as well as in older patients with no discernable brain injury.

Microbleeds found near the outer surface of the brain have been associated with deposition of the amyloid protein in the blood vessels. This is the same protein that is found in great quantities in the brains of people diagnosed with Alzheimer's disease. Tiny bleeds deeper in the brain - in the mid and lower subcortical sectors - have been linked to hypertension, which is high blood pressure. Both of these types of bleeds are associated with intracerebral hemorrhages.

Few studies have compared the prevalence of microbleeds by race or ethnicity, so the Georgetown researchers set out to test if differences exist in the frequency and location of these bleeds between racial groups. They enrolled 87 patients receiving care at two Washington hospitals.

The researchers found that the 42 black patients studied were younger and more frequently had hypertension compared to the 45 older white patients. They also discovered that microbleeds were much more prevalent in the black patients: 74 percent had one or more microbleeds compared to 42 percent in white patients.

Furthermore, they found that while the location of the primary hemorrhage that caused a stroke did not differ by race, white patients had more surface microbleeds and black patients had more subcortical deep bleeds. And, importantly, 38 percent of black participants had a greater frequency of microbleeds in both the brain's outer layer and deep within, compared to 22 percent of white patients who demonstrated microbleeds in both areas.

"This is a small study, and we don't yet know the significance of the greater frequency of microbleeds in our black patients nor why they are located in several different brain areas," Kidwell says. "We would like to know if the presence, location, and quantity of these microbleeds provide information that can be used to better tailor patient care."
-end-
The study was funded by grants from the National Institute of Neurological Disorders and Stroke.

Study co-authors include Brittany Copenhaver, a second year medical student, as well as physicians and researchers from the Washington Hospital Center, in Washington, D.C., Suburban Hospital Stroke Program, in Bethesda, Maryland, and the National Institutes of Health. The authors report no conflicts of interests./p>

About Georgetown University Medical Center

Georgetown University Medical Center is an internationally recognized academic medical center with a three-part mission of research, teaching and patient care (through our partnership with MedStar Health). Our mission is carried out with a strong emphasis on public service and a dedication to the Catholic, Jesuit principle of cura personalis -- or "care of the whole person." The Medical Center includes the School of Medicine and the School of Nursing and Health Studies, both nationally ranked, the world-renowned Lombardi Comprehensive Cancer Center and the Biomedical Graduate Research Organization (BGRO), home to 60 percent of the university's sponsored research funding.

Georgetown University Medical Center

Related Stroke Articles from Brightsurf:

Stroke alarm clock may streamline and accelerate time-sensitive acute stroke care
An interactive, digital alarm clock may speed emergency stroke care, starting at hospital arrival and through each step of the time-sensitive treatment process.

Stroke patients with COVID-19 have increased inflammation, stroke severity and death
Stroke patients who also have COVID-19 showed increased systemic inflammation, a more serious stroke severity and a much higher rate of death, compared to stroke patients who did not have COVID-19, according a retrospective, observational, cross-sectional study of 60 ischemic stroke patients admitted to UAB Hospital between late March and early May 2020.

'Time is vision' after a stroke
University of Rochester researchers studied stroke patients who experienced vision loss and found that the patients retained some visual abilities immediately after the stroke but these abilities diminished gradually and eventually disappeared permanently after approximately six months.

More stroke awareness, better eating habits may help reduce stroke risk for young adult African-Americans
Young African-Americans are experiencing higher rates of stroke because of health conditions such as high blood pressure, diabetes and obesity, yet their perception of their stroke risk is low.

How to help patients recover after a stroke
The existing approach to brain stimulation for rehabilitation after a stroke does not take into account the diversity of lesions and the individual characteristics of patients' brains.

Kids with headache after stroke might be at risk for another stroke
A new study has found a high incidence of headaches in pediatric stroke survivors and identified a possible association between post-stroke headache and stroke recurrence.

High stroke impact in low- and middle-income countries examined at 11th World Stroke Congress
Less wealthy countries struggle to meet greater need with far fewer resources.

Marijuana use might lead to higher risk of stroke, World Stroke Congress to be told
A five-year study of hospital statistics from the United States shows that the incidence of stroke has risen steadily among marijuana users even though the overall rate of stroke remained constant over the same period.

We need to talk about sexuality after stroke
Stroke survivors and their partners are not adequately supported to deal with changes to their relationships, self-identity, gender roles and intimacy following stroke, according to new research from the University of Sydney.

Standardized stroke protocol can ensure ELVO stroke patients are treated within 60 minutes
A new study shows that developing a standardized stroke protocol of having neurointerventional teams meet suspected emergent large vessel occlusion (ELVO) stroke patients upon their arrival at the hospital achieves a median door-to-recanalization time of less than 60 minutes.

Read More: Stroke News and Stroke Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.