Study: Shingles Could Increase Risk of Cognitive Decline

New study findings from Brigham and Women’s Hospital found that an episode of shingles connects to a 20% higher risk for subjective cognitive decline— emphasizing the importance of receiving a shingles vaccine.¹

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Shingles, medically known as herpes zoster (HZ) is a viral infection caused by the varicella zoster virus (VZV) that can result in a painful rash. VZV is the same virus that causes chicken pox and once infected, it remains in the body for the individual’s entire life. Usually, the virus does not reoccur, but if it does, it reactivates as shingles. Data has shown that most individuals in the US 50 years and older have been infected with VZV, making them at risk of developing shingles.¹

Previous research has suggested that shingles could contribute to cognitive decline through neuroinflammation or direct neuronal injury, according to study authors. Subjective cognitive decline is defined as an individual’s experience of failing or commonly occurring confusion or memory loss. The study authors noted that these signs are an early symptom of Alzheimer disease and related dementias. However, evidence on the association between HZ and cognitive decline, in relation to APOE ε4-carrier status has not been studied.^1,2

"Given the growing number of Americans at risk for this painful and often disabling disease and the availability of a very effective vaccine, shingles vaccination could provide a valuable opportunity to reduce the burden of shingles and possibly reduce the burden of subsequent cognitive decline,” Sharon Curhan, MD, of the Channing Division for Network Medicine at Brigham and Women's Hospital, said in a news release.¹

Curhan and her team included 149,327 individuals from 3 large cohort studies—the Nurses’ Health Study (NHS), NHSII, and Health Professionals Follow-Up Study (HPFS). The individuals in the cohorts completed health status surveys every 2 years that contained questions about shingles episodes and cognitive decline. The study aimed to assess the connection between shingles and subsequent subjective cognitive decline (SCD) by comparing those with shingles and those that did not have shingles.^1,2

The results displayed that among individuals with a history of shingles was significantly and independently connected with a 20% higher risk of SCD in men and women. The multivariable-adjusted relative risk (MVRR) of a 3-unit increment in SCD score was higher in comparison to no history of shingles. Additionally, the researchers also found that the risk was higher among men who were carriers of the gene APOE4, that is linked to cognitive impairment and dementia, according to study authors.^1,2

“Our findings show long-term implications of shingles and highlight the importance of public health efforts to prevent and promote uptake of the shingles vaccine,” said Curhan.¹

However, the researchers are unaware of the mechanisms that link VZV to cognitive health but have found a connection to the virus with cognitive decline. The study authors noted that this includes a link to VZV and vascular disease, which could cause damage to blood vessels in the brain or body. Other mechanisms include inflammation in the brain caused by the virus which could result in nerve and brain cell damage, as well as the triggering of other herpesviruses.¹

Curhan and the team intend to further their research to learn more on the prevention of shingles and its related complications, according to study authors.^1,2

“We’re evaluating to see if we can identify risk factors that could be modified to help reduce people’s risk of developing shingles,” said Curhan. “We also want to study whether the shingles vaccine can help reduce the risk of adverse health outcomes from shingles, such as cardiovascular disease and cognitive decline.”¹

REFERENCES

1. Brigham study finds shingles increased risk of subsequent cognitive decline. EurekAlert!. News release. August 13, 2024. Accessed September 6, 2024. https://www.eurekalert.org/news-releases/1054506

2. Herpes zoster and long-term risk of subjective cognitive decline. Alzheimer's Research & Therapy. News release. August 14, 2024. Accessed September 6, 2024. https://alzres.biomedcentral.com/articles/10.1186/s13195-024-01511-x