Brain bleeds increase the risk of dementia

Weill Cornell Medicine researchers have found that intracranial hemorrhages, or "brain bleeds" caused by a ruptured blood vessel in the brain, double a person’s risk of developing dementia later in life.

While the connection between dementia and ischemic strokes caused by clots that block blood supply to the brain has received more attention, the new study, published Jan. 30 in Stroke, extends previous findings to hemorrhages. 

“We consistently see an elevated risk of dementia, regardless of the type of bleed,” said first author Dr. Samuel Bruce, assistant professor of neurology at Weill Cornell Medicine and a neurologist at NewYork-Presbyterian/Weill Cornell Medical Center. This suggests people who have experienced an intracranial hemorrhage should be regularly screened for cognitive impairment because the results could inform future care decisions for patients and their families.

Using Medicare insurance claims from 2008 to 2018, Dr. Bruce and his colleagues assessed almost 15,000 people who had various types of intracranial hemorrhages, which cause blood to collect in brain tissue or underneath the skull. Hemorrhages can occur after head injuries, but the researchers focused on those that happened spontaneously. They observed a two-fold increase in the incidence of first-ever dementia diagnosis within an average of 5.6 years after an intracranial hemorrhage for these patients, compared with over two million people who did not have a hemorrhage.

The results add to literature from other labs showing that hemorrhages are linked to later cognitive problems. In a study based on medical records in Denmark, for example, 11.5% of people developed dementia after blood vessels ruptured within their brains, about a 2.5-fold increase over the general population. On the other hand, ischemic strokes, typically caused by blood clots, increased the risk of dementia by about 1.7-fold.

“Why does an intracranial hemorrhage increase the risk of dementia? There are a few possible reasons,” said senior author Dr. Santosh Murthy, associate professor of neuroscience at the Feil Family Brain & Mind Research Institute and of neurology at Weill Cornell Medicine. Hemorrhages may cause dementia directly by triggering the accumulation of a protein called amyloid beta in the brain and its blood vessels, which can disrupt brain function. Or hemorrhage and dementia may be indirectly connected because the same factors—like chronic damage to blood vessels in the brain—increase the risk of both conditions.

“As we see more evidence that dementia can follow hemorrhages, we really need to consider the implications,” said Dr. Murthy, who is also a neurologist at NewYork-Presbyterian/Weill Cornell Medical Center. “For example, assessing the safety of anti-amyloid beta treatments for Alzheimer’s disease in people who have experienced a hemorrhage should become a research priority."

The researchers concluded that as new treatments developed for intracranial hemorrhages may ultimately lead to patients living longer after an incident, further studies will need to explore how hemorrhages contribute to different subtypes of dementia.