Blood clots caused by vaccines do not have credible evidence linking them to dementia later in life. Current authoritative research indicates that vaccines, including those for shingles, may actually reduce the risk of dementia and cardiovascular events rather than increase it.
To understand this fully, it is important to clarify the relationship between vaccines, blood clots, and dementia:
1. **Blood Clots and Vaccines:**
Some vaccines, particularly certain COVID-19 vaccines, have been very rarely associated with blood clotting events, such as vaccine-induced immune thrombotic thrombocytopenia (VITT). However, these events are extremely rare and typically acute, occurring shortly after vaccination rather than causing long-term chronic conditions. There is no established mechanism or evidence that these rare clotting events lead to dementia years later.
2. **Dementia and Its Causes:**
Dementia is a complex neurodegenerative condition primarily caused by progressive brain cell damage, often linked to Alzheimer’s disease, vascular issues, or other neurological disorders. While vascular dementia is related to blood flow problems in the brain, this is generally due to chronic conditions like hypertension, stroke, or atherosclerosis, not isolated clotting events from vaccines.
3. **Vaccines and Dementia Risk:**
Recent large-scale studies have found that vaccines, especially the shingles vaccine, are associated with a *reduced* risk of dementia. For example, a metastudy analyzing 19 previous studies found that the shingles vaccine was linked to a 20% reduction in dementia risk[1]. Another study published in *Nature* and *JAMA* in 2025 provided evidence suggesting that herpes zoster (shingles) vaccination may causally reduce dementia occurrence[3].
4. **Vaccines and Cardiovascular Health:**
Vaccination against infections like shingles also appears to lower the risk of cardiovascular events such as heart attacks and strokes, which are risk factors for vascular dementia. A study presented at the 2025 European Society of Cardiology Congress showed a 16-18% reduction in cardiac events among vaccinated adults[1]. This cardiovascular protection indirectly supports brain health by reducing vascular damage that could contribute to dementia.
5. **Safety Profiles of Vaccines:**
Safety monitoring systems such as VAERS (Vaccine Adverse Event Reporting System) show that serious adverse events from vaccines like the recombinant zoster vaccine (RZV) are rare and mostly transient. Common side effects are mild and short-lived, and no disproportionate signals have been found linking vaccines to long-term neurological damage or dementia[2][4].
6. **Infection and Dementia Link:**
Chronic infections and inflammation have been implicated in increasing dementia risk. Vaccines prevent infections that might otherwise contribute to systemic inflammation and vascular damage, thereby potentially lowering dementia risk[3]. This supports the idea that vaccines are protective rather than harmful in the context of cognitive decline.
In summary, the scientific consensus based on current authoritative studies is that vaccines do not cause blood clots that lead to dementia later in life. Instead, vaccines, particularly the shingles vaccine, are associated with a decreased risk of dementia and cardiovascular events. The rare clotting events linked to some vaccines are acute and do not translate into long-term neurodegenerative disease. Vaccination remains a safe and effective tool for protecting both cardiovascular and brain health.
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**Sources:**
[1] New Atlas, “Shingles vaccine linked to hear
