Older adults who received the Shingrix shingles vaccine were 24 percent less likely to be diagnosed with dementia over four years than those who did not get the shot, according to a study of more than 500,000 people led by Brown University researchers.
Fewer dementia diagnoses after vaccination
The researchers studied adults who entered skilled nursing facilities in the United States, comparing those who received at least one of the two Shingrix doses with those who were not vaccinated. To join the study group, patients could not have a prior dementia diagnosis and had to be eligible for the vaccine. After four years of follow-up, dementia had been diagnosed in 18.8 percent of vaccinated participants, compared with 24.6 percent of those who were not vaccinated.
One in 17 cases possibly prevented
That gap suggests about one in 17 dementia cases in the vaccinated group may have been prevented, the authors said. The finding adds to earlier evidence from Wales, where a Stanford-led study found that older adults who received a shingles vaccine were 20 percent less likely to develop dementia over seven years. Shingrix is already recommended for adults aged 50 and older and is more than 90 percent effective at preventing shingles itself.
What the study cannot prove
The research was observational, so it cannot prove that the vaccine protects the brain. People who get vaccinated may differ from those who do not in ways the analysis could not fully capture. The authors disclosed funding from GlaxoSmithKline, which makes Shingrix, and noted the company had no control over the study design, the analysis or the decision to publish results. Outside experts said the findings are promising enough to justify trials designed to test the link directly.