Dementia is a condition that includes memory loss and difficulties with thinking which prevent a person from carrying out their normal daily activities. It places a major burden on families and health services and is now the leading cause of death in England and Wales. While some factors that contribute to dementia are well-understood, around two thirds of cases of dementia do not have a recognised cause. Better understanding of the causes of dementia is important to identify effective ways to prevent the condition. Recent research from Taiwan suggests that shingles - a painful blistering rash caused by the chickenpox virus - can increase the risk of dementia. We do not know whether there is a similar effect in the United Kingdom (UK) population.
In this study, we will explore whether UK adults aged over 40 years who have had shingles are more likely to develop dementia than a group of similar adults who have not experienced shingles. To do this, we will use data from General Practitioner (GP) and hospital electronic health records to compare dementia rates between these groups, controlling for other factors such as age. This will help policymakers to understand which groups of people should receive shingles vaccination.
The global burden of dementia is increasing as populations age. While some lifestyle, health and social risk factors for dementia are well-recognised, modifiable factors account for only one third of dementia cases. Recent evidence shows that chronic reactivating neurotropic herpesviruses can trigger acute cardiovascular events such as stroke, which in turn increase dementia risk. Potential mechanisms linking viruses such as herpes zoster (shingles) and stroke include systemic inflammation, and/ or vasculopathy, in which viral infection of cerebral arteries leads to pathological vascular remodelling. National data from Taiwan suggests that ophthalmic zoster is associated with an increase in dementia risk at five years, but there is no comparable published data from the UK.
Here we aim to investigate the association between herpes zoster and incident dementia in a large powerful population cohort using electronic health records data. We will use propensity scores to match patients exposed and unexposed to herpes zoster to improve baseline comparability. We will compare hazard ratios for incident dementia among adults aged >/=40 years with and without zoster exposure using Cox regression. We will carry out a range of sensitivity analyses to check the robustness of our models. This will inform future research around zoster vaccine policy.
Primary outcome: Incident dementia (all types)
- Secondary outcome: Incident dementia subtypes
- Secondary outcome: New onset symptoms of memory loss
Charlotte Warren-Gash - Chief Investigator - London School of Hygiene & Tropical Medicine ( LSHTM )
Charlotte Warren-Gash - Corresponding Applicant - London School of Hygiene & Tropical Medicine ( LSHTM )
Elizabeth Williamson - Collaborator - London School of Hygiene & Tropical Medicine ( LSHTM )
Harriet Forbes - Collaborator - London School of Hygiene & Tropical Medicine ( LSHTM )
James Borgas-Howard - Collaborator - London School of Hygiene & Tropical Medicine ( LSHTM )
Judith Breuer - Collaborator - University College London ( UCL )
Liam Smeeth - Collaborator - London School of Hygiene & Tropical Medicine ( LSHTM )
Suhail Ismail Shiekh - Collaborator - London School of Hygiene & Tropical Medicine ( LSHTM )
HES Admitted Patient Care;HES Outpatient;Patient Level Index of Multiple Deprivation;Practice Level Index of Multiple Deprivation