{"id":4532,"date":"2026-11-06T13:41:24","date_gmt":"2026-11-06T10:41:24","guid":{"rendered":"https:\/\/www.sonerduzguner.com\/?p=4532"},"modified":"2026-11-06T16:24:40","modified_gmt":"2026-11-06T13:24:40","slug":"zona-asisi-alzheimer-demans","status":"publish","type":"post","link":"https:\/\/www.sonerduzguner.com\/en\/zona-asisi-alzheimer-demans\/","title":{"rendered":"Does the Shingles Vaccine Reduce the Risk of Alzheimer\u2019s and Dementia?"},"content":{"rendered":"
\nThe shingles vaccine is given to protect against painful shingles. Could the same vaccine also reduce the likelihood of developing dementia later in life?<\/p>\n

Research published in recent years has brought this question to the attention of scientists. In particular, the approximately 20% lower probability of a dementia diagnosis<\/strong> reported in a study in Wales attracted the interest of many people over 50. Nature, 2025<\/a><\/p>\n

Current evidence suggests a promising possible additional benefit. However, the shingles vaccine has not yet been shown to definitively prevent Alzheimer\u2019s disease or treat dementia. Its established purpose is to prevent shingles and the long-lasting nerve pain that can follow it. Current evidence review<\/a>, European Medicines Agency<\/a><\/p>\n

<\/span>How might shingles and dementia be linked?<\/span><\/h2>\n

Shingles develops when the varicella-zoster virus, which also causes chickenpox, reactivates. After chickenpox, the virus can remain dormant in nerve tissue and reactivate with increasing age or weakened immunity. European Medicines Agency<\/a><\/p>\n

Researchers think that viral reactivation may contribute to processes that affect brain health in some people. Possible pathways include effects on blood vessels in the brain and inflammatory responses in the nervous system.<\/p>\n

However, studies examining shingles and subsequent dementia have not produced entirely consistent results. The effects of age, other illnesses and overall health are difficult to separate. Therefore, having shingles does not mean that a person will develop Alzheimer\u2019s disease.<\/strong> Review of VZV and dementia, 2026<\/a><\/p>\n

<\/span>Are Alzheimer\u2019s disease and dementia the same?<\/span><\/h2>\n

Dementia is a syndrome affecting memory, thinking and the ability to carry out everyday tasks, and can be caused by different diseases. Alzheimer\u2019s disease is its most common cause. Other forms include vascular dementia. World Health Organization<\/a><\/p>\n

This distinction matters when interpreting news about shingles vaccination. A decrease in overall dementia diagnoses does not demonstrate that Alzheimer\u2019s disease has been prevented to the same extent.<\/p>\n

<\/span>What does \u201c20% lower risk\u201d in the Welsh study mean?<\/span><\/h2>\n

The study, published in Nature in 2025, used the birth-date eligibility rule of the Welsh vaccination programme. People of almost identical ages on either side of the eligibility threshold were compared.<\/p>\n

The researchers estimated that receiving the live shingles vaccine reduced the probability of a new dementia diagnosis over seven years by approximately 20% in relative terms<\/strong>. The absolute difference was 3.5 percentage points. This does not mean that \u201c20 out of every 100 people are protected against dementia.\u201d Welsh study<\/a><\/p>\n

This approach aims to reduce differences that can influence comparisons, such as vaccinated people taking greater care of their health. Nevertheless, the findings must be interpreted within the assumptions of the method, the accuracy of health records and the age group studied.<\/p>\n

<\/span>Is there also evidence for the recombinant shingles vaccine used today?<\/span><\/h2>\n

Yes. Dementia research is not limited to the older live vaccine.<\/p>\n

A study published in Nature Medicine in 2024<\/strong> compared recipients of the recombinant vaccine with recipients of the live shingles vaccine. The recombinant vaccine was associated with more favourable dementia outcomes over six years. The reported \u201c17% increase in diagnosis-free time\u201d is not the same as a \u201c17% reduction in dementia risk\u201d; it represents a different statistical measure. Taquet and colleagues, 2024<\/a><\/p>\n

Research published in Nature Communications in 2026<\/strong> compared 65,800 adults aged 65 and over who received two doses of recombinant vaccine with 263,200 unvaccinated people. Vaccination was associated with less dementia. However, the association became smaller when the comparison group consisted of recipients of another vaccine. This suggests that general health behaviours among vaccinated people may also affect the results. Rayens and colleagues, 2026<\/a><\/p>\n

These studies support a possible benefit. However, differences in vaccine types, age groups and comparison methods mean that a single protective-effect percentage cannot be given.<\/p>\n

<\/span>Why are scientists still cautious?<\/span><\/h2>\n

Vaccinated and unvaccinated people may differ in access to healthcare, preventive health habits and other illnesses. Statistical adjustments can reduce these differences but may not eliminate them.<\/p>\n

A systematic review and meta-analysis published in 2026 found strong evidence supporting protection by recombinant shingles vaccination against shingles, but rated the certainty of evidence for a possible reduction in dementia risk as low<\/strong>. This does not mean there is no association; it means the true effect may differ substantially from current estimates. Systematic review, 2026<\/a><\/p>\n

Another analysis published that year questioned how much of the findings from some natural experiments could be attributed to vaccination and emphasised the need for independent confirmation. Kivim\u00e4ki and colleagues, 2026<\/a><\/p>\n

Fewer dementia diagnoses in health records alone cannot distinguish between complete prevention, delayed clinical symptoms and changes in the timing of diagnosis. Evidence and mechanisms review, 2026<\/a><\/p>\n

<\/span>How might shingles vaccination affect brain health?<\/span><\/h2>\n

Three main possible explanations are being investigated:<\/p>\n