Introduction: The Evolving Landscape of Alzheimer’s Disease Management
The therapeutic landscape for Alzheimer’s disease (AD) has undergone a seismic shift with the emergence of anti-amyloid monoclonal antibodies (mAbs), such as lecanemab and donanemab. These therapies, designed to clear amyloid-beta plaques from the brain, have demonstrated the ability to slow cognitive decline in patients with mild cognitive impairment (MCI) or mild dementia. However, this clinical progress comes with significant safety considerations, most notably Amyloid-Related Imaging Abnormalities (ARIA), which include edema (ARIA-E) and hemorrhage (ARIA-H).
A critical challenge for clinicians is the potential interaction between anti-amyloid mAbs and medications that alter coagulation. Expert consensus and current clinical guidelines generally advise against the co-prescription of these mAbs with anticoagulants or the use of thrombolytics due to a heightened risk of catastrophic intracranial hemorrhage. As these cognitive therapies move into broader clinical use, understanding the frequency with which patients with cognitive impairment develop new medical needs for anticoagulation is paramount for long-term treatment planning and shared decision-making.
Study Design and Methodology
To address this clinical uncertainty, a study published in Neurology by Parks et al. utilized a longitudinal cohort of adults aged 65 years or older from the Health and Retirement Study (2010–2020). The researchers linked this data with Medicare claims to track clinical outcomes over time. The study population consisted of 12,373 participants with a mean age of 73 years, 59% of whom were female. Importantly, all included participants had no previous indication for anticoagulants at the start of the observation period.
Cognitive status was categorized into three groups: normal cognition, MCI, or dementia. The research team employed Fine-Gray survival models, which are specifically designed to account for the competing risk of death—a crucial factor in an aging population. The primary objective was to estimate the 1-year incidence of five major cardiovascular conditions that typically necessitate the use of anticoagulants or thrombolytics: atrial fibrillation (AF), deep vein thrombosis (DVT), pulmonary embolism (PE), acute myocardial infarction (AMI), and ischemic stroke.
Key Findings: The Cumulative Risk of New Indications
The results of the study provide a sobering look at the cardiovascular vulnerability of patients with cognitive impairment. Within just one year of follow-up, a significant portion of the cohort developed indications that would traditionally require blood-thinning medications.
Incidence in Patients with Mild Cognitive Impairment (MCI)
For participants with MCI—the primary target population for current anti-amyloid therapies—the 1-year risk for any new indication was 5.7%. The specific breakdown of events included:
- Atrial Fibrillation: 1.7%
- Ischemic Stroke: 2.0%
- Deep Vein Thrombosis: 1.2%
- Acute Myocardial Infarction: 1.2%
- Pulmonary Embolism: 0.4%
Incidence in Patients with Dementia
The risk was even higher in the dementia group, with a cumulative 1-year incidence of 6.7% for any new indication. The distribution of events was as follows:
- Atrial Fibrillation: 1.7%
- Ischemic Stroke: 2.4%
- Deep Vein Thrombosis: 1.8%
- Acute Myocardial Infarction: 1.0%
- Pulmonary Embolism: 0.3%
These data suggest that approximately 1 in 15 patients with cognitive impairment will develop a condition requiring anticoagulation or thrombolysis within twelve months of a cognitive assessment. This rate is remarkably high when considering the multi-year duration of treatment required for anti-amyloid mAbs.
Expert Commentary: Navigating the Trade-offs
The biological plausibility for increased bleeding risk in these patients is well-established. Anti-amyloid mAbs work by removing amyloid from the brain parenchyma, but they also interact with amyloid deposited in the walls of cerebral blood vessels (Cerebral Amyloid Angiopathy, or CAA). This process can weaken the vascular integrity. When an anticoagulant or a thrombolytic (like tPA for an acute stroke) is introduced, the risk of a major intraparenchymal hemorrhage increases substantially.
From a clinical perspective, these findings introduce a complex “prognostic paradox.” A clinician may initiate a patient on an anti-amyloid mAb today, only to find that six months later, the patient develops new-onset atrial fibrillation. At that point, the clinician and patient face a harrowing choice: continue the mAb and risk a major brain bleed, or discontinue the mAb and potentially lose the cognitive benefits while facing the embolic risks of AF.
Furthermore, the high incidence of stroke (2.0% to 2.4%) is particularly concerning. If a patient on an anti-amyloid mAb arrives at the emergency department with an acute ischemic stroke, they may be ineligible for life-saving thrombolysis because of their mAb status, leading to worse functional outcomes from the stroke itself.
Clinical Implications and Shared Decision-Making
These findings emphasize that the eligibility for anti-amyloid therapy is not a static state but a dynamic one. The study suggests that clinicians must incorporate cardiovascular risk stratification into their neurological workup. Patients with high CHADS-VASc scores or other markers of cardiovascular frailty may be poor candidates for anti-amyloid mAbs, even if they meet the cognitive and biomarker criteria for the drugs.
Shared decision-making must now include a discussion about the “future risk of needing anticoagulation.” Families need to understand that starting these medications might limit their options for treating other common conditions of aging, such as AF or stroke, in the near future.
Conclusion and Future Directions
The study by Parks et al. provides essential real-world data that bridges the gap between controlled clinical trials and geriatric practice. While anti-amyloid monoclonal antibodies offer hope for slowing the progression of Alzheimer’s disease, their safety profile is inextricably linked to the patient’s overall cardiovascular health. The 5.7% to 6.7% annual risk of developing a new indication for anticoagulation or thrombolysis is a significant factor that must be weighed against the modest cognitive benefits of mAb therapy.
Future research should focus on validating these findings in specific populations eligible for lecanemab or donanemab and investigating whether certain biomarkers can predict which patients are at the highest risk for both cognitive decline and cardiovascular events. For now, vigilance and proactive cardiovascular management remain the cornerstones of safe neuro-therapeutic practice.
References
1. Parks AL, Lykken JM, Rieu-Werden ML, et al. Risk of New Indications for Anticoagulants and Thrombolytics in People With Cognitive Impairment: Implications for Anti-Amyloid Therapy. Neurology. 2026;106(2):e214489.
2. van Dyck CH, Swanson CJ, Aisen P, et al. Lecanemab in Early Alzheimer’s Disease. New England Journal of Medicine. 2023;388(1):9-21.
3. Cummings J, Apostolova L, Rabinovici GD, et al. Lecanemab: Appropriate Use Recommendations. The Journal of Prevention of Alzheimer’s Disease. 2023;10(3):362-377.
