A recent study published in the journal Cell has found that shingles vaccination may lower the risk of developing dementia and reduce deaths related to dementia among older adults. The research used population data from Wales to investigate how the herpes zoster (HZ) vaccine affects rates of mild cognitive impairment (MCI) and dementia.
The study focused on individuals born between September 1, 1925, and September 1, 1942, who were living in Wales as of September 1, 2013. For MCI analysis, over 282,000 people without previous cognitive impairment were included. For the analysis of dementia mortality, more than 14,000 individuals with a prior diagnosis of dementia before September 2013 were considered.
Researchers applied a regression discontinuity design by comparing people born just before and after the HZ vaccine eligibility cutoff date of September 2, 1933. This approach allowed them to estimate causal effects because both groups were nearly identical except for their eligibility for vaccination.
Over nine years of follow-up, about seven percent of participants developed MCI. Eligibility for HZ vaccination was associated with a reduction in new MCI diagnoses by 1.5 percentage points; among those who actually received the vaccine, this reduction was 3.1 percentage points. These results held up across different statistical methods and time frames.
Among those already diagnosed with dementia at baseline, nearly half died from dementia during the follow-up period. Vaccine eligibility reduced dementia-related deaths by 8.5 percentage points; actual vaccination reduced deaths by almost thirty percent.
The effect was more pronounced in women than men: "Eligibility and vaccination decreased new MCI diagnoses by 2.5 and 5.1 percentage points, and deaths due to dementia by 13.9 and 52.3 percentage points, respectively," according to researchers’ findings for women only.
Further analyses suggested that HZ vaccination might have greater protective effects against mixed forms of dementia compared with Alzheimer’s or vascular types but did not show significant benefits for non-dementia causes of death or for men.
The authors concluded: "This study provides strong quasi-experimental evidence suggesting that HZ vaccination may meaningfully reduce the risk of cognitive decline and dementia-related mortality, with benefits observed across multiple stages of the clinical disease course as inferred from MCI incidence and dementia-related death outcomes."
They noted that while mechanisms remain unclear—especially concerning why benefits appear stronger in women—preventing reactivation of neurotropic viruses like varicella zoster could support better neuroimmune health in aging populations.
Researchers recommend further studies on newer vaccines covering broader age groups and longer-term outcomes beyond nine years.
