April 13 (HealthDay News) -- A Dutch study finds an increased incidence of tiny bleeding episodes in the brains of people who regularly take aspirin.
Magnetic resonance imaging (MRI) examinations of 1,062 people found a 70 percent higher incidence of "microbleeds" among those taking aspirin or carbasalate calcium, a close chemical relative of aspirin, than among those not taking such anti-clotting drugs, according to an April 13 online report in the Archives of Neurology from physicians at Erasmus MC University Medical Center in Rotterdam. The research was expected to be published in the June print issue of the journal.
No increased incidence of microbleeds was seen in people taking clot-preventing drugs that act in different ways, such as heparin, the researchers noted.
Both aspirin and carbasalate calcium are taken to reduce the risk of cardiovascular problems such as heart attack and stroke. Both prevent formation of clots by acting against platelets, the blood cells that form clots.
The report adds information to a still unfolding medical story about the causes and effects of microbleeds, said Dr. Steven M. Greenberg, a professor of neurology at Harvard Medical School and director of the Hemorrhagic Stroke Research Program at Massachusetts General Hospital.
"They found an association between taking antiplatelet medications and having microbleeds," Greenberg said. "That is not proof that the antiplatelet medications are causing the microbleeds. People typically are given antiplatelet medication because they have more cardiovascular risk factors, which are associated with microbleeds. They tried to adjust for those risk factors, but that doesn't prove that taking the medications causes the microbleeds."
And then, "it is not clear at this point what significance we can attach to seeing microbleeds," Greenberg said. Some studies have shown an association between microbleeds and an increased risk of major bleeding events in the brain, but those studies have included only small numbers of people, he added.
There also is some data indicating that microbleeds are associated with reduced brain function, but their role is unclear, because "they tend to travel together with other kinds of small-vessel brain disease," Greenberg said.
"It's not clear at this point whether microbleeds are doing any substantial harm to the brain, but we do know that antiplatelet drugs help prevent heart attacks and strokes," Greenberg said.
The most that can be said is that the study "is a little bit of a warning for us to think about antiplatelet drug therapy as a risk for hemorrhagic damage to the brain," he said.
Therefore, there is no message to physicians yet about who should or should not be prescribed antiplatelet drugs such as aspirin, Greenberg said.
"It's important not to overreact until we are sure of what gives people the best combination of benefit without much risk," he said.
SOURCES: Steven M. Greenberg, professor, neurology, Harvard Medical School, and director, Hemorrhagic Stroke Research Program, Massachusetts General Hospital, Boston; April 13, 2009, Archives of Neurology, online