No evidence that herpes zoster is associated with increased risk of dementia diagnosis

Association between hospital-treated infectious diseases and risk of neurodegenerative disease among patients with prediabetes and diabetes: A prospective cohort study in UK Biobank

BACKGROUND

Previous evidence suggests that infectious diseases may contribute to the development of neurodegenerative diseases (NDDs) while individuals with hyperglycemia may be at increased risk for both infection and NDDs due to dysregulated inflammation levels. This study aimed to examine the association between hospital-treated infectious diseases and the risk of NDDs among patients with prediabetes and diabetes and whether the associations differed by the number of infections and potential effect modifiers.

STUDY DESIGN AND METHOD

Using data from the UK Biobank, we conducted a prospective study involving 69,731 individuals, consisting of 48,149 participants with prediabetes and 21,582 participants with diabetes. Hospital-treated infectious diseases and NDDs were identified through record linkage to Health Episode Statistics and the Scottish Morbidity Records. Cox regression models were applied to assess the association between hospital-treated infectious diseases and the risk of developing NDDs, and to evaluate the trend of this association in relation to the number of infections. The modification effects by age, sex, smoking status, alcohol consumption, sleep duration, body mass index (BMI), glycated hemoglobin (HbA1c) levels, comorbidities, and diabetes medication use were investigated.

RESULTS

Over a median follow-up of 10.75 years, 1,867 participants (2.57 per 1,000 person-years) were diagnosed with NDDs. We found hospital-treated infectious diseases were significantly associated with an increased risk of NDDs among both individuals with prediabetes or diabetes (adjusted HR [aHR] 3.11, 95 % CI 2.83-3.42). Specifically, hospital-treated infectious diseases were associated with a higher risk of developing Alzheimer's disease, vascular dementia, all-cause dementia, Parkinson's disease, and multiple sclerosis. Moreover, a greater number of infection diagnoses was associated with a higher risk of NDDs. Consistent associations between infection and an increased risk of NDDs were observed, regardless of factors representing age, sex, lifestyle, and diabetes severity.

CONCLUSIONS

Hospital-treated infectious diseases were significantly associated with the risk of NDDs in individuals with diabetes and prediabetes, with similar associations observed for bacterial and viral infections. These findings emphasize the importance of implementing infection prevention strategies and monitoring of infectious comorbidities in the management of NDDs among patients with prediabetes and diabetes.

Herpes zoster as risk factor for dementia: a matched cohort study over 20 years in a 10-million population in Italy

BACKGROUND

Herpes Zoster is caused by the reactivation of the Varicella-Zoster Virus. Zoster may influence the occurrence of dementia, but contradictory results about this association emerged from recent studies. These findings did not consider the severity of Zoster and observed individuals for limited follow-up time. Our study used a region-wide Italian registry to investigate the association between severe Zoster infection and dementia occurrence over a 23-year period.

METHODS

We included people aged ≥ 50 and hospitalised with Zoster, and two comparison cohorts from both the general population and the hospitalised population without Zoster. By random sampling, the matching 1:5 was based on sex, birth year, and entry date in the cohort. Dementia and Zoster were identified through validated algorithms. A Fine-Gray sub-distribution hazard model was used, accounting for competing risk of death.

RESULTS

We identified 132,968 individuals, of whom 12,088 with severe Zoster, 60,440 matched controls among the general population, and 60,440 matched controls among the hospitalised population. In severe cases of Herpes Zoster, the overall adjusted sub-distributed hazard ratio of dementia was 1.13 (95 % CI 1.07-1.19) compared to the general population, and 1.08 (95 % CI 1.03-1.14) compared to hospitalised population. Hazard ratios were still significant in different strata group, including by sex, age group (including in 50-65 younger adults) and at different follow-up period.

CONCLUSIONS

Our population-based study found an increased risk of developing dementia among severe Zoster cases. Those results support the importance of improving Zoster prevention and extending the vaccination recommendations to younger age groups.

[Varicella zoster infection as a risk factor for dementia: a scoping review]

A scoping review analyzing 21 selected publications was conducted to determine "whether the varicella zoster virus (VZV) is a risk factor for dementia". One meta-analysis concluded that VZV infection increases dementia risk, while another meta-analysis contradicts this finding. Several reports have shown an increased risk of dementia associated with VZV infections of the eyes and central nervous system. Additionally, a third meta-analysis reported that VZV vaccination reduces dementia. Therefore, VZV infection may be a risk factor for dementia. However, most of the reviewed articles were retrospective cohort studies, which limits the strength of conclusions that can be drawn. To provide more robust evidence, prospective cohort studies and clinical trials are needed to evaluate the impact of VZV itself, as well as the effectiveness of vaccines and antiviral therapies.

Association between herpes zoster and Parkinson's disease and dementia: a systematic review and meta-analysis

Objectives

This meta-analysis investigated the relationship between herpes zoster and the risk of dementia or Parkinson's disease by analyzing published clinical studies.

Methods

We systematically searched PubMed, Cochrane, Embase, and Web of Science Core Collection databases on April 25, 2024. Hazard ratios (HR) were used for statistical analyses. Random-effects models were applied, and heterogeneity was assessed using the I2 statistic.

Results

Herpes zoster was associated with a non-significant trend toward increased dementia risk (HR = 1.11, 95% CI 0.99-1.24, p = 0.07) but significantly increased Parkinson's disease risk (HR = 1.15, 95% CI 1.03-1.30, p = 0.02). Subgroup analyses revealed that herpes zoster significantly elevated the risk of the prospective study subgroup (HR = 1.08, 95% CI 1.02-1.13, p = 0.004) and vascular dementia subgroup (HR = 1.17, 95% CI 1.00-1.37, p = 0.05). Significant heterogeneity was observed for both outcomes (dementia: I 2 = 98%, p < 0.00001; Parkinson's disease: I 2 = 94%, p < 0.00001).

Conclusion

Herpes zoster raises the risk of Parkinson's disease and vascular dementia, with a potential causal link to dementia. Early vaccination against herpes zoster is recommended over post-infection antiviral treatment to mitigate risks.

Systematic review registration

https://www.crd.york.ac.uk/PROSPERO/ and our registration number is CRD42024555620.

Herpes zoster and long-term risk of subjective cognitive decline

BACKGROUND

Herpes zoster (HZ), commonly known as "shingles," may contribute to cognitive decline through mechanisms such as neuroinflammation or direct neuronal injury. However, evidence on the longitudinal association between HZ and cognitive decline is conflicting and whether the risk differs by APOE ε4-carrier status has not been studied; prospective cohort studies on the association between HZ vaccination and cognitive decline are also lacking.

METHODS

We included 149,327 participants from three large cohorts-the Nurses' Health Study (NHS), NHSII, and Health Professionals Follow-Up Study (HPFS)-to prospectively examine the association between HZ and subsequent subjective cognitive decline (SCD). Poisson regression was used to estimate the multivariable-adjusted relative risk (MVRR) of a 3-unit increment in SCD score according to years since HZ compared with participants with no history of HZ.

RESULTS

Compared with individuals with no history of HZ, the MVRR (95% CI) of a 3-unit increment in SCD score was significantly and independently higher among individuals with a history of HZ, but the duration of time since HZ when the elevated risk of SCD was statistically significant differed among the cohorts. In NHS, HZ was associated with higher long-term risk of SCD; compared with individuals with no history of HZ, the MVRR (95% CI) of a 3-unit increment in SCD score was 1.14 (1.01, 1.32) for ≥ 13 years since HZ. In NHS II, HZ was associated with higher risk of SCD in both the short-term [MVRR 1.34 (1.18, 1.53) for 1-4 years] and long-term [MVRR 1.20 (1.08, 1.34) for ≥ 13 years since HZ]. In HPFS, an elevated risk of SCD was suggested across all time points. Among the subset of participants with information on APOE ε4, there was a suggestion that the association differed by APOE ε4 carrier status, but the results were not consistent between women and men. Among the subset of women with information on HZ vaccination, there was a suggestion that the long-term risk of SCD may be greater among women who were not vaccinated against HZ.

CONCLUSIONS

Data from three large independent cohorts of women and men showed that HZ was associated with higher long-term risk of SCD, and the risk may differ by APOE ε4-carrier status.

Assessing Risk Factors for Cognitive Decline Using Electronic Health Record Data: A Scoping Review

Background

The data and information contained within electronic health records (EHR) provide a rich, diverse, longitudinal view of real-world patient histories, offering valuable opportunities to study antecedent risk factors for cognitive decline. However, the extent to which such records' data have been utilized to elucidate the risk factors of cognitive decline remains unclear.

Methods

A scoping review was conducted following the PRISMA guideline, examining articles published between January 2010 and April 2023, from PubMed, Web of Science, and CINAHL. Inclusion criteria focused on studies using EHR to investigate risk factors for cognitive decline. Each article was screened by at least two reviewers. Data elements were manually extracted based on a predefined schema. The studied risk factors were classified into categories, and a research gap was identified.

Results

From 1,593 articles identified, 80 were selected. The majority (87.5%) were retrospective cohort studies, with 66.3% using datasets of over 10,000 patients, predominantly from the US or UK. Analysis showed that 48.8% of studies addressed medical conditions, 31.3% focused on medical interventions, and 17.5% on lifestyle, socioeconomic status, and environmental factors. Most studies on medical conditions were linked to an increased risk of cognitive decline, whereas medical interventions addressing these conditions often reduced the risk.

Conclusions

EHR data significantly enhanced our understanding of medical conditions, interventions, lifestyle, socioeconomic status, and environmental factors related to the risk of cognitive decline.

The associations of herpes simplex virus and varicella zoster virus infection with dementia: a nationwide retrospective cohort study

BACKGROUND

In this study, the risk of dementia in patients with a history of herpes simplex virus (HSV) or varicella zoster virus (VZV) infection was evaluated.

METHODS

This nationwide cohort study used data from the Korean National Health Insurance Service collected between 2006 and 2017. A total of 752,205 subjects ≥ 45 years of age not diagnosed with dementia until 2006 were included. A multivariate Cox regression model, adjusted for age, sex, and other comorbidities, was used to assess the hazard ratio (HR) for dementia based on VZV or HSV infection. The interaction effects of both viral infections were analysed. Viral infections are classified into four categories: eye, central nervous system (CNS), simple, and complicated. The hazard ratio (HR) of viral infection was analysed based on the type of dementia.

RESULTS

In multivariable analysis, both HSV and VZV infection were associated with an increased risk of dementia (HR = 1.38, 95% confidence interval, CI:1.33-1.43) and (HR = 1.41, 95% CI:1.37-1.46), respectively. Patients who experienced both HSV and VZV infections were also at an increased risk of dementia (HR = 1.57, 95% CI:1.50-1.63). The co-infection group showed the shortest time from viral infection to dementia diagnosis (4.09 ± 3.02 years). In the subgroup analysis, all types of HSV and VZV infections were associated with an increased risk of dementia compared to the non-infection group. The eye, CNS, and complicated VZV infections were associated with a significantly higher risk than simple VZV infections. There were no significant differences between the subtypes of HSV infection. Furthermore, HSV, VSV, and co-infection were associated with an increased risk of all dementia types, including Alzheimer's disease (AD) and vascular dementia (VD).

CONCLUSIONS

Individual HSV and VZV infections were associated with an increased risk of all types of dementia, including AD and VD. Patients co-infected with HSV and VZV, VZV infection in the eye, CNS, or complicated type were more vulnerable to the development of dementia.

Risk of dementia following herpes zoster infection among patients undertreatment versus those not: A systematic review and meta-analysis

Background and Aims

According to the previous studies, herpes zoster (HZ) has been associated with cognitive function and dementia. There is a hypothesis claiming that dementia risk may be reduced by receiving the antiviral treatment for HZ. The purpose of this systematic review and meta-analysis was to shed light on the association between dementia and HZ in individuals receiving and not receiving antiviral medications.

Methods

Studies investigating the association between HZ and dementia were identified through a systematic search in PubMed/MEDLINE, Scopus, Embase, Google Scholar, and Cochrane Library databases from January, 2000 to April, 2022. Data on the risk of dementia in HZ-infected patients under and not under antiviral treatment were extracted. The meta-analysis was conducted using a random-effects model. The modified ROBIN-I tool was used to evaluate the risk of bias assessment. By utilizing the funnel plots, publication bias was investigated.

Results

Six cohort studies on 538,531 patients were included. The overall risk of bias assessment was moderate. According to evidence-based cohort studies, there was a significant direct association between HZ and risk of dementia in patients with HZ, who did not receive antiviral treatments (hazard ratio [HR]: 1.15, 95% confidence interval [CI]: 1.03 to 1.28, p = 0.01). On the other hand, there was an inverse relationship between HZ and risk of dementia among patients with HZ, who received antiviral treatments (HR: 0.68, 95% CI: 0.59 to 0.77, p < 0.001).

Conclusions

This study demonstrated that antiviral therapies may significantly lower the risk of dementia in patients with HZ. This study also confirmed that patients with HZ, without receiving antiviral therapies, may have an increased risk of developing dementia. Further longitudinal research is warranted in this area.

Herpes Zoster and Risk of Incident Parkinson's Disease in US Veterans: A Matched Cohort Study

BACKGROUND

Although some systemic infections are associated with Parkinson's disease (PD), the relationship between herpes zoster (HZ) and PD is unclear.

OBJECTIVE

The objective is to investigate whether HZ is associated with incident PD risk in a matched cohort study using data from the US Department of Veterans Affairs.

METHODS

We compared the risk of PD between individuals with incident HZ matched to up to five individuals without a history of HZ using Cox proportional hazards regression. In sensitivity analyses, we excluded early outcomes.

RESULTS

Among 198,099 individuals with HZ and 976,660 matched individuals without HZ (median age 67.0 years (interquartile range [IQR 61.4-75.7]); 94% male; median follow-up 4.2 years [IQR 1.9-6.6]), HZ was not associated with an increased risk of incident PD overall (adjusted HR 0.95, 95% CI 0.90-1.01) or in any sensitivity analyses.

CONCLUSION

We found no evidence that HZ was associated with increased risk of incident PD in this cohort. © 2024 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

The association between varicella zoster virus and dementia: a systematic review and meta-analysis of observational studies

PURPOSE

The relationship between varicella zoster virus (VZV) infection and the risk of dementia has not been previously studied specifically. Therefore, this study sought to determine the relationship between studying VZV infection and dementia occurring in the general population by conducting an extensive meta-analysis of published cases.

METHOD

A systematic literature search was conducted in seven online databases by October 31, 2022. Heterogeneity was tested by the I2 index. Pooled HR and 95% CI were used to estimate the effect of VZV infection on dementia. Sensitivity analyses and publication bias were also performed.

RESULT

Nine studies involving 3,326,673 subjects were included. VZV infection was associated with an increased risk of dementia (HR = 1.11, 95% CI: 1.02-1.21). The risk of dementia was reduced in those who received antiviral therapy compared to those who did not (HR = 0.84, 95% CI: 0.71-0.99). In addition, VZV infection was found to be associated with an increased risk of developing dementia in the pooled results of the moderate quality study (HR = 1.81,95% CI: 1.27-2.59), and this association persisted when subgroup analyses were performed based on region (Asia: HR = 1.18,95% CI: 1.04-1.33).

CONCLUSIONS

Our results suggest that VZV infection might increase the risk of developing dementia, but there is no clear mechanism about the true relationship, and since there is no effective treatment for dementia, and our results suggest that some populations can benefit from antiviral therapy, it is at least arguable that patients who develop VZV infection should be treated with appropriate antiviral medications.

Herpes Zoster virus infection and the risk of developing dementia: A systematic review and meta-analysis

BACKGROUND

Herpes Zoster, commonly known as shingles, is a viral infection that affects a significant portion of the adult population; however, its potential role in the onset or progression of neurodegenerative disorders like dementia remains unclear.

METHODS

We searched the following databases: PubMed, Scopus, Cochrane library, and Web of Science. We included any randomized control trials and controlled observational studies as Cross-sectional, prospective, or retrospective cohort and case-control studies that investigated the prevalence of dementia in Herpes Zoster Virus (HZV)-infected patients and HZV-free control group or if the study investigated the prevalence of HZV in demented patients. Also, if the studies measured the levels of dementia biomarkers in patients with HZV compared with a healthy control group.

RESULTS

After the complete screening, 9 studies were included in the meta-analysis. In the outcome of the incidence of HZV, the pooled analysis showed no statistically significant difference between the dementia group and the No dementia group (RR = 1.04% CI = 0.86-1.25, P = .70). In the outcome of incidences of dementia and Alzheimer's disease, the pooled analysis showed no statistically significant difference between the HZV group and the incidence of dementia (RR = 0.99, 95% CI = 0.92-1.08, P = .89), (RR = 3.74, 95% CI = 0.22-62.70, P = .36) respectively. In the outcome of incidences of Herpes Zoster ophthalmicus (HZO), the generic inverse variance showed a statistically significant association between patients who have HZO and increased incidence of dementia (RR = 6.26, 95% CI = 1.30-30.19, P = .02).

CONCLUSION

Our study showed no significant association between HZV and the incidence of dementia or Alzheimer's disease, but it shows a significant association between HZO and the incidence of dementia. More multicenter studies are needed to establish the actual association between the HZV and dementia.

The association of herpes zoster and influenza vaccinations with the risk of developing dementia: a population-based cohort study within the UK Clinical Practice Research Datalink

BACKGROUND

Dementia affects ability to remember, think, or make decisions that interfere with doing everyday activities. There is no cure, therefore any prevention or delay of the onset is of importance. This study aims to investigate the association between zoster and influenza vaccinations and the risk of developing dementia.

METHODS

We conducted a retrospective population-based cohort study using electronic health records from 1469 general practices contributing to the Clinical Practice Research Datalink (CPRD) Aurum database with linked hospital episode statistics (HES) and Office for National Statistics (ONS) mortality records. We built two 'matched cohorts': zoster vaccine (854,745 exposed individuals) matched with 8.8 million comparators without a history of zoster vaccination, and influenza vaccine (742,487 exposed individuals) matched with 7.12 million comparators without a history of vaccination as another comparator group. The cohorts were then followed to assess the association of exposure (vaccine) with outcome (dementia diagnosis).

RESULTS

Zoster vaccination was associated with a lower risk of dementia diagnosis (adjusted hazard ratio (HR) 0.78 with 95% CI: 0.77-0.79), Alzheimer's diagnosis (adjusted HR 0.91 with 95% CI: 0.89-0.92 and other types of dementia (adjusted HR 0.71 with 95% CI: 0.69-0.72). Influenza vaccination also was associated with a slightly reduced hazard of dementia risk (adjusted HR 0.96 with 95% CI: 0.94-0.97).

CONCLUSION

Both zoster vaccine for prevention of shingles / herpes zoster and influenza vaccine to prevent influenza were associated with diminished risk of dementia, with the zoster association appearing more pronounced.

Maintaining a 'fit' immune system: the role of vaccines

INTRODUCTION

Conventionally, vaccines are thought to induce a specific immune response directed against a target pathogen. Long recognized but poorly understood nonspecific benefits of vaccination, such as reduced susceptibility to unrelated diseases or cancer, are now being investigated and may be due in part to "trained immunity'.

AREAS COVERED

We discuss 'trained immunity' and whether vaccine-induced 'trained immunity' could be leveraged to prevent morbidity due to a broader range of causes.

EXPERT OPINION

The prevention of infection i.e. maintaining homeostasis by preventing the primary infection and resulting secondary illnesses, is the pivotal strategy used to direct vaccine design and may have long-term, positive impacts on health at all ages. In the future, we anticipate that vaccine design will change to not only prevent the target infection (or related infections) but to generate positive modifications to the immune response that could prevent a wider range of infections and potentially reduce the impact of immunological changes associated with aging. Despite changing demographics, adult vaccination has not always been prioritized. However, the SARS-CoV-2 pandemic has demonstrated that adult vaccination can flourish given the right circumstances, demonstrating that harnessing the potential benefits of life-course vaccination is achievable for all.