Severe Herpes Zoster Raises Dementia Risk in Seniors

TOPLINE:

Older adults with severe herpes zoster were at a heightened risk of developing dementia, especially those aged 50-65 years, when compared with both matched control individuals from the general population and patients hospitalised for other infections.

METHODOLOGY:

• Researchers conducted a cohort study from January 2001 to December 2023 in Italy to examine the association between severe herpes zoster disease and the risk for dementia in adults aged 50 years or older.
• They included data of 132,968 older adults (mean age, 74.6 years; 57.6% women), of whom 12,088 were hospitalised with a diagnosis of herpes zoster, 60,440 were matched control individuals from the general population, and 60,440 were matched control individuals hospitalised for other infections.
• Older adults hospitalised for herpes zoster were included in the study on the basis of the date of their initial hospital admission. They were followed up until the development of dementia, death, emigration, or the end of the study period, whichever occurred first.
• Hospitalised patients diagnosed with herpes zoster were identified using International Classification of Diseases, Ninth Revision, Clinical Modification codes.
• The incidence of dementia was sourced from the following administrative health data: Hospital discharges registry, drug prescriptions, administrative exemptions, and long-term care facilities admissions.

TAKEAWAY:

• An overall increased risk for dementia was observed among older adults hospitalised for herpes zoster compared with matched control individuals from the general population (subdistribution hazard ratio [SHR], 1.13; P < .001) and matched control individuals hospitalised for other infections (SHR, 1.08; P = .001).
• After 1 year of follow-up, a twofold increase in the early dementia risk was observed in the herpes zoster group (SHR, 2.43; P < .001); after 10 years of follow-up, the risk for dementia was 22% higher in the herpes zoster group than in matched control individuals from the general population (SHR, 1.22; P < .001).
• Older adults aged 50-65 years hospitalised for herpes zoster showed a sevenfold higher risk for dementia (SHR, 7.54; 95% CI, 2.35-24.12).

IN PRACTICE:

“[The study] findings support improving immunisation public health strategies and extending the vaccination recommendations to younger people,” the authors wrote.

SOURCE:

This study was led by Lorenzo Blandi, Vita-Salute San Raffaele University, Milan, Italy. It was published online on April 12, 2025, in The Journal of Prevention of Alzheimer’s Disease.

LIMITATIONS:

This study was limited by its retrospective design and the usage of administrative data. Data about medical treatments received for herpes zoster or vaccines administered to prevent herpes zoster were not extracted. Moreover, data from outpatient services were not considered, potentially affecting the outcomes of the study.

DISCLOSURES:

This study did not receive any specific grant from any funding agency.Blandi reported receiving administrative support from the Lombardy Region. The remaining authors declared having no known competing financial interests or personal relationships that could have influenced the work.

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.