Shingles Vaccination May Lead to Reduction in Dementia Diagnoses
Previous research shows herpes zoster is associated with a higher long-term risk of subjective cognitive decline, with increased risk for men who carried APOE ε4.
Data from a study published in Nature showed vaccination against herpes zoster, also known as shingles, reduced the probability of a new dementia diagnosis by approximately 20%. The findings show that vaccination against shingles could be a promising way to prevent or delay dementia among patients.1
Previous research shows herpes zoster is associated with a higher long-term risk of subjective cognitive decline, with increased risk for men who carried APOE ε4. | Image Credit: kittisak - stock.adobe.com
Shingles is a viral infection caused by the varicella-zoster virus, which also causes chickenpox. The infection causes a painful rash or blisters across the skin. Approximately 1 million cases of shingles are reported in the US every year, according to the Cleveland Clinic, and it develops in about 10% of patients who have previously had chickenpox at another point in their lives.2
Patients with a weakened immune system, 50 years and older, who experienced trauma and who are under stress are at risk for developing shingles. Furthermore, after being infected with varicella zoster, the virus remains in the body and will trigger shingles when active again, and it is possible to have shingles more than once. The shingles vaccine has been shown to prevent the virus and is about 90% effective, according to the CDC. Patients who are 50 years and older with a healthy immune system or those 19 years and older with a weakened immune system should get vaccinated.3
In a previous study published in Alzheimer’s Research and Therapy, investigators found that herpes zoster was associated with a higher long-term risk of subjective cognitive decline. However, the risk seemed to differ for those who carried APOE ε4, particularly in men. In the 3 large independent cohorts, herpes zoster was associated with approximately a 20% higher risk of long-term subjective cognitive decline. According to the authors, “evidence suggests that VZV infection may contribute to amyloid-associated pathology, potentially impacting amyloid burden and disease progression in conditions like Alzheimer disease.”4
In the current study, investigators included patients born on or after September 1933 who were eligible for the herpes zoster vaccination for at least 1 year starting on September 1, 2013, in Wales, United Kingdom. They used large-scale electronic health records to compare individuals who were ineligible for the vaccine and those who were eligible by the cut-off date. The investigators included the live-attenuated herpes zoster vaccine (Zostavax).1
During the 7-year follow-up, investigators included a total of 296324 adults, with 14465 developing at least 1 diagnosis of shingles. Further, of 282541 adults in the 7-year follow-up, 35307 developed dementia. The investigators estimated that being eligible for the zoster vaccine had an effect of 1.3 percentage points absolute and an 8.5% relative reduction in the probability of a new dementia diagnosis over the 7-year period. Compared with patients who were ineligible for the vaccine, the vaccine reduced the probability of a new dementia diagnosis by 3.5 percentage points, or a relative reduction of 20% over the 7-year period. Investigators also found that the protective effect of vaccination was higher for women compared with men.1
The investigators believe that the protective effects on dementia diagnosis could be due to 3 mechanisms, including change in health care pathways, reduction in reactivation of varicella zoster virus, and varicella zoster virus-independent immunomodulatory effect.1
“Our quasi-experimental approach reduces the probability of confounding compared with more standard associational analyses,” the study authors concluded.1 “Nonetheless, it is possible (even if statistically unlikely) that our findings are due to chance. Confirmation of our findings in other populations, settings, and data sources is therefore critical.”
