In spring 2026, an exceptionally large nationwide trial was launched in Finland to investigate whether there is a causal link between shingles vaccination and a reduced incidence of dementia. The FinDementia trial is conducted by FVR -Finnish Vaccine Research in collaboration with GlaxoSmithKline (GSK), the manufacturer of the Shingrix® shingles vaccine, together with selected Finnish wellbeing services counties and pharmacy partners. The aim is to recruit approximately 35,000 participants aged 76 and older, with follow-up based on Finland's national health registers.
Dementia is a syndrome in which cognitive functions have declined from a previous level to such an extent that a person’s ability to manage activities of daily living, work or social relationships independently is impaired.
Dementia can be caused by several different diseases. The most common cause of dementia is a progressive memory disorder, of which Alzheimer’s disease is the most common. Cognitive impairment or dementia related to cerebrovascular disease, either alone or in combination with Alzheimer’s disease, are also common in the population.
Progressive memory disorders belong to the group of conditions known as neurodegenerative diseases.
The strongest risk factor for dementia is age. For example, approximately 0.6% of Europeans under the age of 65 have dementia, whereas among people aged over 90 the proportion is approximately 41%.
In addition to age, risk factors for dementia include common chronic conditions, such as hypertension, as well as lifestyle-related factors, including low levels of physical activity.
However, with the exception of genetic factors, the underlying causes of many neurodegenerative diseases, including Alzheimer’s disease, remain poorly understood.
Shingles is a painful blistering skin rash caused by the reactivation of the varicella-zostervirus, a herpesvirus that also causes chickenpox.
After a chickenpox infection, the varicella-zoster virus remains dormant in the body. It resides in the trigeminal and dorsal root ganglia, from which it may reactivate, for example due to impaired immunity, causing symptoms in the dermatome supplied by the affected nerve.
Advancing age increases the risk of shingles, and individuals may experience shingles more than once.
Shingles is treated with antiviral medicines and analgesics. Despite adequate treatment, the disease may leave persistent neuropathic pain in the affected area. When shingles occurs in the facial region, it may cause ophthalmic complications. In some cases, the virus reactivates in the central nervous system, leading to encephalitis and necessitating hospital treatment.
Like varicella-zoster, many other viruses remain in the body for life after an acute infection, either completely dormant or periodically reactivating. Associations between persistent viral infections and several diseases have already been identified.
Researchers are particularly interested in the role of herpesviruses in the development of neurodegenerative diseases. It is thought that latent viruses may contribute to disease processes through several biological mechanisms, and this remains an active area of research.
For example, studies have shown that the risk of memory disorders is higher among people who have had multiple episodes of shingles during their lifetime. Research has also demonstrated that reactivation of herpes simplex virus type 1 in the central nervous system can trigger changes characteristic of Alzheimer’s disease, possibly as part of a protective response against viral replication.
In recent years, several observational studies have suggested that shingles vaccination may be associated with a lower risk of dementia. This association has been more pronounced in women than in men. Several explanations have been proposed. Vaccination may directly reduce the replication of varicella zoster or other herpesviruses. Alternatively, it may stimulate the immune system in ways that reduce inflammation in the central nervous system (neuroinflammation), a process thought to play a role in neurodegenerative diseases.
The FinDementia study aims to evaluate, in a robust randomised trial setting, whether shingles vaccination can reduce the risk of dementia and other neurodegenerative diseases. In addition, the study will investigate the vaccine’s potential effects on cardiovascular diseases and several other health outcomes.
Internationally, FinDementia is unique in both its scale and study design. The findings may provide important new evidence to support dementia prevention and promote healthy ageing. The study is also expected to deliver immediate public health benefits, as 75% of participants, around 25,000 older adults, will receive protection against shingles through vaccination.
Author
Hanna Ansakorpi
Neurologist, MD, PhD, Adj. Prof.
Senior Researcher
FVR – Finnish Vaccine Research
FVR - Finnish Vaccine Research Ltd.
Peltokatu 26, 33100 Tampere
Business ID 3256659-4
info@fvr.fi
Invoicing instructions
Data protection I About cookies I Self-monitoring plan
Osana-tuki: help@fvr.fi
Copyright 2026 FVR - Finnish Vaccine Research
