Summary: Researchers report that intracranial hemorrhages—commonly called brain bleeds—are associated with about a twofold increase in the risk of developing dementia in later years. While ischemic strokes caused by clot-related blocked blood flow have long been linked to cognitive decline, this large U.S. study extends those concerns to spontaneous hemorrhages and highlights the need for proactive cognitive monitoring after such events.
Analyzing Medicare claims for a diverse cohort, investigators found that people who experienced a non-traumatic intracranial hemorrhage were significantly more likely to receive a first-time dementia diagnosis over follow-up. The study suggests several possible pathways for this association—direct effects of blood on brain tissue, promotion of amyloid beta accumulation, or shared vascular vulnerabilities that raise the risk for both bleeding and neurodegeneration.
Given these findings, the authors recommend routine cognitive screening for patients after an intracranial hemorrhage, and they urge further research into how hemorrhages contribute to specific dementia subtypes and how anti-amyloid therapies for Alzheimer’s disease should be evaluated in this population.
Key Facts
- Increased dementia risk: Intracranial hemorrhage was associated with roughly double the risk of incident dementia during follow-up.
- Potential mechanisms: Hemorrhage may promote amyloid beta deposition or share underlying vascular risk factors with neurodegenerative disease.
- Clinical implications: Patients who survive brain bleeds should receive regular cognitive assessments, and researchers should evaluate the safety and appropriateness of Alzheimer’s therapies for these individuals.
Source: Weill Cornell University
Overview of the study
Investigators at Weill Cornell Medicine examined the relationship between non-traumatic intracranial hemorrhage and new diagnoses of dementia using U.S. Medicare claims data collected from 2008 through 2018. The team focused on spontaneous hemorrhages—bleeding that occurs without a recent head injury—and included intracerebral hemorrhage (ICH), subarachnoid hemorrhage (SAH), and subdural hemorrhage (SDH) in the exposure definition.
Using validated ICD-9 and ICD-10 diagnosis codes to identify exposures and outcomes, the researchers assembled a cohort of approximately 2.1 million Medicare beneficiaries. Among them, 14,775 individuals had a new diagnosis of non-traumatic intracranial hemorrhage. Patients with a prior history of intracranial hemorrhage or dementia were excluded so that only incident cases were analyzed.
Over a median follow-up of 5.6 years (interquartile range 3.0–9.1), 2,527 patients (17.1%) who experienced an intracranial hemorrhage were diagnosed with dementia for the first time, compared with 260,691 individuals (12.8%) among those without a hemorrhage. The cumulative incidence of dementia was reported as 8.6% (IQR 8.1–8.9) in the hemorrhage group and 2.2% (IQR 2.0–2.4) in the non-hemorrhage group.
After adjusting for demographics and comorbid conditions in Cox regression models, intracranial hemorrhage was independently associated with a twofold increased risk of incident dementia (hazard ratio [HR] 2.0; 95% confidence interval [CI], 1.9–2.2). Risks varied by hemorrhage subtype: ICH showed the highest associated risk (HR 2.4; CI, 2.2–2.5), followed by SAH (HR 1.99; CI, 1.7–2.2) and SDH (HR 1.6; CI, 1.4–1.7).
Interpretation and implications
The findings reinforce evidence from other national and international datasets that intracranial bleeding increases the likelihood of subsequent cognitive impairment and dementia. Researchers propose a few nonexclusive explanations: bleeding itself could initiate neurodegenerative processes (for example, by promoting amyloid beta accumulation in brain tissue and vessels), or hemorrhage and dementia may share common underlying vascular damage that predisposes patients to both outcomes.
Clinically, these results argue for systematic cognitive screening after spontaneous brain bleeds so that decline can be detected early and care plans adjusted for patients and caregivers. The study team also emphasizes the need for targeted research into whether newly developed treatments for hemorrhage survivors alter long-term dementia risk and whether anti-amyloid therapies intended for Alzheimer’s disease are safe and effective in people with a history of intracranial bleeding.
About this neurology research news
Author: Barbara Prempeh
Source: Weill Cornell University
Contact: Barbara Prempeh – Weill Cornell University
Image credit: Neuroscience News
Original Research: Closed access. “Non-Traumatic Intracranial Hemorrhage and Risk of Incident Dementia in U.S. Medicare Beneficiaries” by Samuel Bruce et al., published in Stroke.
Abstract
Title: Non-Traumatic Intracranial Hemorrhage and Risk of Incident Dementia in U.S. Medicare Beneficiaries
Background: The study evaluated the risk of a first diagnosis of dementia following non-traumatic intracranial hemorrhage in a large and diverse older U.S. population and assessed whether that risk differed by hemorrhage subtype.
Methods: This retrospective cohort study used inpatient and outpatient Medicare claims from January 1, 2008, to December 31, 2018. The exposure was a new diagnosis of non-traumatic intracranial hemorrhage (composite of ICH, SAH, and SDH). The primary outcome was a first-ever dementia diagnosis. The analysis excluded patients with prior intracranial hemorrhage or dementia and employed Cox regression adjusted for demographics and comorbidities. Secondary analyses examined risks by hemorrhage subtype.
Results: Among roughly 2.1 million beneficiaries, 14,775 had an intracranial hemorrhage. During a median follow-up of 5.6 years, incident dementia was diagnosed in 2,527 (17.1%) of those with hemorrhage and 260,691 (12.8%) without hemorrhage. The cumulative incidence was 8.6% in the hemorrhage group versus 2.2% in the non-hemorrhage group. Adjusted analysis showed an increased risk of dementia after intracranial hemorrhage (HR 2.0; CI, 1.9–2.2). Subtype analyses indicated elevated risks for ICH (HR 2.4), SAH (HR 1.99), and SDH (HR 1.6).
Conclusion: In this large, heterogeneous cohort of older U.S. adults, non-traumatic intracranial hemorrhage was independently associated with a twofold higher risk of being diagnosed with dementia. The elevated risk was seen across hemorrhage subtypes, underscoring the importance of follow-up cognitive assessment and further research into mechanisms and treatment implications.