Researchers at Weill Cornell Medicine have discovered that intracranial haemorrhages—commonly referred to as “brain bleeds” resulting from ruptured blood vessels within the brain—can double an individual’s likelihood of developing dementia later in life. While prior studies have predominantly focused on the relationship between dementia and ischaemic strokes, which are caused by blood clots obstructing cerebral blood flow, this new research broadens the understanding by highlighting similar risks associated with haemorrhagic events.
Published on 30 January in the journal Stroke, the study underscores the importance of considering all forms of stroke in discussions about cognitive decline. “We consistently observe a heightened risk of dementia, irrespective of the type of haemorrhage,” stated Dr Samuel Bruce, the study’s lead author and assistant professor of neurology at Weill Cornell Medicine, as well as a practising neurologist at NewYork-Presbyterian/Weill Cornell Medical Center. He emphasised that individuals who have suffered from intracranial haemorrhages should undergo regular screening for cognitive impairment, as such evaluations could play a vital role in shaping future clinical care and support for both patients and their families.
The researchers conducted a comprehensive analysis using Medicare insurance claims data from 2008 to 2018. The cohort included nearly 15,000 individuals who had experienced spontaneous intracranial haemorrhages—excluding those caused by traumatic injury—where bleeding occurred within brain tissue or beneath the skull. When compared with a control group of over two million individuals with no history of brain haemorrhage, the affected patients exhibited a two-fold increase in the likelihood of being diagnosed with dementia for the first time within an average of 5.6 years following the haemorrhagic event.
These findings add to a growing body of international research linking brain haemorrhages to subsequent cognitive decline. For instance, a study utilising Danish medical records reported that approximately 11.5% of individuals who experienced intracranial haemorrhages went on to develop dementia, a rate approximately 2.5 times higher than that of the general population. By comparison, ischaemic strokes were associated with a more modest, though still significant, 1.7-fold increase in dementia risk.
The reasons behind the apparent connection between haemorrhagic stroke and dementia are still being investigated. According to senior author Dr Santosh Murthy, associate professor of neuroscience at the Feil Family Brain & Mind Research Institute and neurology at Weill Cornell Medicine, there are several possible mechanisms. One hypothesis suggests that brain haemorrhages may directly contribute to dementia by accelerating the build-up of amyloid beta, a protein implicated in Alzheimer’s disease, within brain tissue and vasculature. Alternatively, the relationship may be indirect, with both haemorrhages and dementia arising from shared risk factors such as chronic vascular damage or age-related neurodegeneration.
Dr Murthy stressed the broader implications of these findings for both clinical practice and future research. “As evidence continues to accumulate showing a link between brain bleeds and dementia, we must consider how this affects treatment approaches,” he noted. In particular, he highlighted the importance of re-evaluating the safety and efficacy of anti-amyloid beta therapies—used in treating Alzheimer’s disease—in patients with a history of haemorrhage. Such considerations, he argued, should be elevated to a research priority.
In conclusion, the study raises important questions about the long-term impact of intracranial haemorrhages on brain health. As medical advances improve survival rates following such events, there is an urgent need for further investigations into how haemorrhages might contribute to different forms and stages of dementia. These insights could inform individual treatment strategies and broader public health initiatives to mitigate the burden of cognitive decline in ageing populations.
More information: Samuel Bruce et al, Nontraumatic Intracranial Hemorrhage and Risk of Incident Dementia in US Medicare Beneficiaries, Stroke. DOI: 10.1161/STROKEAHA.124.050359
Journal information: Stroke Provided by Weill Cornell Medicine
