Dementia is described by the NHS as a syndrome associated with an “ongoing decline of brain functioning”. This may manifest in an impaired ability to remember, think, or make decisions, suggests the CDC. The most common type of dementia is Alzheimer’s disease, and although dementia generally affects older patients, it is not considered a “part of normal ageing”. The WHO states that around 55 million people worldwide who experience dementia, with 10 million cases added each year. For these patients and their families, the experience of dementia can be deeply upsetting, confusing, and frightening. So, how do we deal with it now?
Current efforts and immune potential
FDA-approved drugs comprise 2 categories of Alzheimer’s treatment. The first option is to change disease progression, and the second is to temporarily mitigate some symptoms. However, we do not have a cure for Alzheimer’s disease or most cases of dementia.
Therefore, researchers are exploring the possibility of protection from dementia through vaccination. We are familiar with the traditional approach of vaccines, which encourage or train the immune system to respond to specific infections. Might this be applicable to dementia? Dr David A. Merrill, of Providence St John’s Health Centre in Santa Monica, told MedicalNewsToday that a growing “appreciation” of the immune system’s role indicates it might be “relevant” to “potentially recovering from or even preventing a disease”.
For example, research presented at the Alzheimer’s Association International Conference in 2020 suggested that flu and pneumonia vaccinations were associated with a reduced risk of developing Alzheimer’s. Dr Merrill suggests that “treatments can and should involve helping or addressing immune system function with ageing”.
How would a vaccine work?
Dr Heather Snyder of the Alzheimer’s Association described an exciting time for research, with numerous therapies in development. However, she is also interested in “active immunisation, such as vaccines”.
“They are, in some cases, leveraging the biology of decades of vaccine-related development more broadly in medical care.”
Some of the molecules in the body that are associated with dementia would be targeted by a dementia vaccine. These include:
- Beta-amyloid proteins – abnormal levels of these form plaques that disrupt cell function
- Tau – proteins that stabilise the structure of neurons in the brain, often abnormally folded in Alzheimer’s patients’ brains
- Alpha-synuclein – a protein in neurons that is associated with Parkinson’s disease and Lewy body dementia in abnormal levels
- Who is exploring vaccines?
MedicalNewsToday suggests that several vaccines are in various stages of clinical trials. These include a nasal vaccine in the US, and a Swiss-based candidate. Vaxxinity also announced in 2022 that it had received fast-track designation for an immunotherapeutic vaccine for Alzheimer’s disease.
Dr Michael G Agadjanyan at The Insititute for Molecular Medicine in the US is developing a vaccine for Alzheimer’s that can “delay/halt the onset”. The goal, he suggests, is to develop an “immunogenic vaccine that can induce a sufficient level of antibodies in the periphery of all vaccinated cognitively unimpaired elderly with immunosenescence”.
Although several options are being explored, Dr Merrill believes it will take a “number of years” for candidates to get through the process and “regulatory hurdles”. Furthermore, Dr Snyder thinks that “more research in large, diverse human populations” is needed before any chance of “comment on the potential usefulness of a vaccine”.
Is this likely?
There is also the concern that people might be hesitant towards vaccines for dementia, particularly depending on the length of the vaccination process. If there is a clear indication that it “truly protects” the patient, Dr Merrill hopes people would “line up”. However, things at the moment are “uncertain”.
As well as public reluctance, there is debate among the scientific community as to whether a vaccine would be successful. Dr Karl Herrup of the University of Pittsburgh School of Medicine believes that attempting to harness the immune system against the predicted root causes of the disease, “rests on shaky grounds”. Specifically discussing therapies, he describes the “bitter disappointment” of results that are “not surprising”.
“I would rather be wrong and have a useful Alzheimer’s disease therapy than be right and have to have millions of people continue to suffer”.
He suggests that the only significant question is if the treatment can “meaningfully alter the disease course”.