What's new: Women and Mexican Americans appear to be at higher risk of a type of stroke that causes bleeding in the space between the brain and its surrounding tissues.
The finding: An ongoing study of strokes among the residents of Corpus Christi, Texas, has reported that women account for more than two-thirds of the city's cases of a kind of stroke called a subarachnoid hemorrhage -- even though they make up just over half of the city's population. The report, published in the journal Neurology earlier this month, showed that women in the study were 74% more likely than men to suffer a subarachnoid hemorrhage. It also found that Mexican Americans in the city were 67% more likely to suffer a subarachnoid hemorrhage than non-Hispanic whites. Mexican Americans accounted for 60% of the city's subarachnoid hemorrhage cases but make up just 48% of the city's population. The study excluded Asians and African Americans, who didn't suffer enough strokes to be included in the analysis.
How the study was done: The study is part of a bigger project, called the Brain Attack Surveillance in Corpus Christi (BASIC) study. As part of the project, researchers from the University of Michigan at Ann Arbor combed through county hospital and coroner records to count every stroke case that occurred in the southeastern Texas town between the beginning of 2000 and the end of 2006. In the current study, the researchers analyzed the fraction of Corpus Christi's stroke population suffering a subarachnoid hemorrhage: 117 out of more than 5,500 total cases of stroke.
Why it matters: Doctors and researchers are constantly on the lookout for ways to reduce death and impairment due to stroke, which is the top cause of disability in this country and the third leading cause of death. Studies that provide a clearer picture of who's at risk help public health experts target stroke-prevention campaigns. Most stroke cases are caused by so-called ischemic strokes, in which a clogged artery cuts off blood circulation to part of the brain. Ischemic strokes typically affect older adults. But subarachnoid hemorrhages can strike at any age -- making it a challenge to reach out to those at risk.
The current study bolsters the findings of previous, smaller studies that suggested subarachnoid hemorrhages were more common in women and some Hispanic populations. With its diverse, well-established immigrant population, Corpus Christi provides an ideal setting for studying stroke patterns in the population, as well as stroke prevention, says the study's lead author, Dr. Lewis Morgenstern, professor of neurology and director of the stroke program at the University of Michigan Cardiovascular Center: "It's a microcosm of what the U.S. will look like in 20 to 30 years."
What we still don't know: Researchers suspect that genetics may play a significant role in determining a person's risk of any kind of stroke, but they've only just begun to identify specific stroke-linked genes. However, though genetics may help explain the apparent racial and ethnic patterns at risk for various stroke types, many researchers think that behaviors -- such as smoking, drinking or dietary habits -- also play a part.
Morgenstern has another idea. "I personally feel a lot of it has to do with access to healthcare," he says. Half of all people who suffer a subarachnoid hemorrhage could avoid serious injury or even death if they recognized the common warning sign, a so-called thunderclap headache, he adds. He thinks that spreading the word about warning signs could help save lives among stroke victims -- but that remains to be proven.
In Explain This, we decipher new medical studies. To read past columns, go to www.latimes.com/explain.