More Evidence: Protective Effects of Shingles Vaccine
A new study published in the Annals of Internal Medicine adds to growing evidence that shingles vaccination may reduce the risk of dementia in older adults.Researchers found that people who received a single dose of the shingles vaccine were less likely to develop dementia than those who were not vaccinated.
By evaluating the electronic health data from more than half a million senior citizens in the United States in skilled nursing facilities, scientists calculated that the shingles vaccine reduced the risk of dementia by about 24% within four years of receiving at least one dose of the shingles vaccine. Shingrix, the recombinant zoster vaccine, is the current shingles vaccine in use in the U.S. It is delivered in two doses.
Those who already had dementia or just had shingles were excluded from the study, as well as those who were terminally ill or passed away within a year of being admitted to the care facility.
This study and others like it indicate but do not prove that the shingles vaccine prevents dementia. Other unaccounted for factors may influence who gets dementia. For example, those who receive vaccines may be more likely to receive health care in general, which could lower their risk in other ways.
Less than 9,000 of over 500,000 seniors in the study had received the shingles vaccine.
Preventing Dementia
According to the lead author of the study, Kaley Hayes, PharmD, PhD, from the Brown University School of Public Health, this “translates to about one in 17 dementia cases potentially being prevented through vaccination.”
According to the World Health Organization, 57 million people had dementia as of 2021, with 10 million new cases every year. Alzheimer's disease is the most common form of dementia. There is no cure for dementia.
Barrires to Vaccination
Older adults may not receive the shingles vaccine due to cost, transportation problems, scheduling difficulties, and simply not being advised by their doctor to get the vaccine. Pharmacies and health clinics face challenges in supply and the cost and logistics of storing vaccines on site.
Many older adults have concerns about the vaccine's effectiveness, side-effects, and safety. Often people do not know about the benefits. Older adults with lower income, lower educational attainment, and less knowledge about shingles are generally less willing to be vaccinated.
The Wealthy, Educated, Healthier Get Vaccinated
Vaccination is more common among adults with higher income and education levels, prescription drug coverage, and who receive preventive healthcare regularly. Individuals in poorer health are less likely to be vaccinated, despite the potential for being at greater risk for shingles complications.
People tend to get the shingles vaccinate when others they interact with do, or if they receive the flu vaccine.
Why Might a Shingles Vaccine Affect Dementia?
Researchers do not yet know exactly why shingles vaccination appears to reduce dementia risk.
One possibility is that preventing shingles, which is a reactivation of the varicella-zoster (chicken pox) virus, protects the brain from inflammation. Scientists have increasingly recognized that infections can trigger inflammatory responses that affect the nervous system. Chronic inflammation has long been suspected of contributing to Alzheimer's disease and other forms of dementia. Preventing viral reactivation also reduces damage to the nervous system over time.
Vaccination itself helps train or regulate the immune system in ways that support long-term brain health. Some vaccines have been associated with health benefits that extend beyond protection against the disease they were originally designed to prevent.
There is also evidence that shingles infections may directly affect blood vessels and nervous system tissues, causing damage that shows as cognitive decline. Preventing those infections could also prevent dementia.
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