The study, published in the July issue of Ethnicity and Disease, also shows twice the incidence of hypertension and five times the number of people with hypertension who weren't taking their blood-pressure medicine among those who had had an intracerebral hemorrhage, compared to healthy, age-matched controls. Alcohol use also was associated with an increase in risk.
"African-American patients experience a two-fold higher risk of intracerebral hemorrhage compared to white patients," said Adnan I. Qureshi, UB assistant professor of neurosurgery and lead author on the study. "This high incidence of intracerebral hemorrhage contributes significantly to death, disability and loss of productivity in young populations.
"In the absence of any definitive treatment for intracerebral hemorrhage, significant stress needs to be placed on primary prevention and understanding of factors that predispose to a higher risk in young African Americans," he said.
Internal bleeding, also known as intracerebral hemorrhage (ICH), can occur in any part of the brain. Blood may accumulate in the tissues as well as in the space between the brain and the membranes covering the brain, a subarachnoid hemorrhage. Bleeding may be isolated in a part of one cerebral hemisphere (lobar intracerebral hemorrhage) or occur in other brain structures, such as the thalamus, basal ganglia, pons, or cerebellum (deep intracerebral hemorrhage).
ICH occurs in about 20 out of 100,000 people, statistics show, and can affect any person regardless of age, sex or race, but appears to occur more frequently in African Americans, striking the young and middle-aged disproportionately. The incidence of intracerebral hemorrhage in African Americans reaches nearly 50 out of 100,000 persons, Qureshi noted.
Since there is no effective treatment for ICH, prevention takes center stage, but little information has been available on the factors that put this population at higher risk. This study is the first to use a case-control approach to tease out these risks. It assessed health and lifestyle histories of 122 African Americans between the ages of 18 and 45 admitted to a public hospital in Atlanta with ICH between December 31, 1997, and January 1, 1990. This information was compared with data from 366 African Americans in the same age group without the condition who took part in the most recent National Health and Nutrition Examination Survey (NHANES III).
Researchers included data on hypertension, diabetes, smoking, cocaine use, alcohol use, and stroke or heart disease from all participants, as well as the record of prescriptions for hypertension medication and compliance with their use.
Results showed that cocaine use was the strongest risk factor associated with ICH in this population, even higher than hypertension, Qureshi said. "While the mechanism for this association isn't clear, we suspect that the sudden elevation in blood pressure that occurs immediately after using cocaine may cause an existing aneurysm or arteriovenous malformation (AVM) in the brain to rupture." Several clinical studies of stroke among cocaine users have found a high frequency of aneurysm or AVM, he noted.
Hypertension, particularly in those who had been prescribed medication but took it irregularly, also was shown to be an important high-risk factor for ICH. These findings suggest that physicians should focus more on compliance than on screening, Qureshi said.
"In chronic hypertension, the body develops a certain protective response in an effort to counter high blood pressure's effects. Taking blood-pressure medication intermittently may impair the development of this response and may make patients more vulnerable to blood pressure fluctuations." The bottom line, Qureshi said, is that a reduction in the high rate of death and disability associated with intracerebral hemorrhage can't occur without effective preventive measures. "The study demonstrated the presence of factors in the community that easily can be modified to reduce this risk. These include avoidance of cocaine use and regular use of blood pressure medication as prescribed."
Also participating in the study were M. Fareed K. Suri, M.D.; Lee R. Guterman, Ph.D., M.D., and L. Nelson Hopkins, M.D., of the Department of Neurosurgery, UB School of Medicine and Biomedical Sciences; and Yousef Mohammad, M.D.; Janet Braimah, and Michael R. Frankel, M.D., of the Department of Neurology, Emory University School of Medicine.