A shingles vaccine might offer an unexpected benefit: dementia prevention. Emerging research suggests that vaccines designed to prevent the painful condition of shingles may also play a role in protecting the aging brain.
A recent study indicates that shingles vaccination could reduce an older adult's risk of developing dementia by 20% over a seven-year period.
Published in the journal Nature, the study underscores the growing understanding of the multifaceted influences on brain health during aging and highlights potential interventions.
According to Dr. Pascal Geldsetzer from Stanford University, the lead researcher, the findings are notably robust, with women potentially experiencing greater benefits, which is significant given their higher risk of dementia.
The study examined individuals in Wales around the age of 80 who received the initial shingles vaccine more than ten years ago. Health officials now advise adults aged 50 and over to receive a newer vaccine that offers enhanced protection against shingles.
Dr. Maria Nagel, a specialist in viruses affecting the nervous system at the University of Colorado Anschutz Medical Campus, suggests that these findings provide an additional incentive for vaccination.
Dr. Nagel emphasizes that the shingles virus poses a risk for dementia, and vaccination presents a viable risk-reduction strategy.
Given the increasing prevalence of Alzheimer's and other dementias in an aging population, Dr. Anupam Jena, a physician and health economist at Harvard, notes that the implications of the study are substantial in a commentary published in Nature.
Individuals who have had chickenpox, which includes most people born before 1980, carry the dormant virus throughout their lives. This virus can reactivate when the immune system weakens due to illness or age, leading to shingles, characterized by painful, blister-like sores typically on one side of the body.
Statistics from the Centers for Disease Control and Prevention (CDC) indicate that approximately one in three Americans will develop shingles. While most individuals recover, severe complications can occur, including vision loss if the virus affects the eye. Furthermore, up to 20% of shingles patients may experience persistent nerve pain for months or even years after the rash resolves.
The exact mechanisms underlying Alzheimer's and other dementias are not fully understood. However, viruses that infiltrate the nervous system, particularly those in the herpes family like the chickenpox virus, are suspected to contribute to the factors that increase vulnerability.
Last year, researchers at Brigham and Women's Hospital in Boston reported that a shingles episode could elevate an individual's dementia risk by approximately 20%.
This increased risk is partly attributed to the virus-induced inflammation, which can harm organs, including the brain. Nagel from Colorado also points out that the virus can directly infect brain blood vessels, causing clots and impaired blood flow, thereby increasing the risk of stroke and dementia.
Intriguingly, her lab's research has revealed that shingles can stimulate the production of amyloid, a sticky protein associated with Alzheimer's disease.
It has been noted that adults who adhere to recommended vaccination schedules often engage in other brain-healthy behaviors, such as regular exercise and a nutritious diet, making it challenging to isolate the specific benefits of vaccination.
Dr. Geldsetzer from Stanford capitalized on a unique situation in Wales, where shingles vaccinations were initially limited by age. Individuals aged 80 or older on September 1, 2013, were ineligible, while those aged 79 could receive the vaccine. This allowed researchers to compare similar individuals who narrowly qualified or missed the cutoff, mimicking a randomized study design.
Dr. Geldsetzer's team scrutinized over 280,000 medical records, revealing that vaccination provided some degree of protection against dementia, with participants receiving the first-generation vaccine, Zostavax.
Dr. Nagel suggests that the next critical step involves assessing whether the current vaccine, Shingrix, also confers dementia protection. Recent research suggests that it does. The vaccine manufacturer GSK recently announced a partnership with UK health officials to monitor the cognitive health of vaccinated seniors.
Dr. Geldsetzer is keen to investigate the earlier vaccine further to ascertain if the type of vaccine influences the outcome.
Shingrix is administered in two doses, spaced a few months apart. The CDC advises that most individuals aged 50 and over, as well as younger adults with weakened immune systems—including those who previously received the first-generation shingles vaccine—should get vaccinated. However, fewer than 40% of eligible Americans have been vaccinated.
Common side effects include pain at the injection site, as well as fever, achiness, and flu-like symptoms. The CDC recommends that individuals who are currently fighting another virus, such as the flu or COVID-19, should postpone their shingles vaccination until they have fully recovered.
While there is no guaranteed way to prevent dementia, healthcare professionals advise adopting healthy habits to mitigate the risk, such as maintaining social and cognitive engagement, managing high blood pressure, and controlling high blood sugar levels for individuals with diabetes, all of which are linked to cognitive decline.