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

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

“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 haemorrhage 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, Bruce and his colleagues assessed nearly 15,000 people who had various types of intracranial haemorrhages, which cause blood to collect in brain tissue or underneath the skull. Haemorrhages 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 haemorrhage for these patients, compared with more than 2 million people who did not have a haemorrhage.

The results add to previous literature from other labs showing that haemorrhages 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 haemorrhage increase the risk of dementia? There are a few possible reasons,” said senior author Santosh Murthy, associate professor of neuroscience at the Feil Family Brain & Mind Research Institute and of neurology at Weill Cornell Medicine.

Haemorrhages 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 haemorrhage 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 haemorrhages, we need to consider the implications,” said 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 haemorrhage should become a research priority.”

The researchers conclude that new treatments developed for intracranial haemorrhages may ultimately lead to patients living longer after an incident and motivate the need to be regularly screened for cognitive impairment.

Saima Sidik is a freelance writer for Weill Cornell Medicine.