Vaccines are arguably one of the greatest inventions of medical science of all time. Now, researchers are looking to take vaccine technology one step further to protect against neurodegenerative diseases like dementia. In this Special Feature, we asked experts about what is currently under development, how a dementia vaccine would work, and how quickly we may see one becoming available to the public.
Dementia is an umbrella term referring to a range of disorders that affect the way in which a person’s brain works, causing symptoms including memory loss, behavior changes, and difficulty speakingTrusted Source and walking.
The most common form of dementia is Alzheimer’s disease, which accounts for 60% to 80% of dementia cases.
More than 55 millionTrusted Source people around the world have dementia, with about 10 million cases added each year.
There are some Food and Drug Administration (FDA)-approved drugs for Alzheimer’s disease aimed at either changing disease progression or helping lower some symptoms of the condition. However, there is currently no cure for Alzheimer’s disease or most cases of dementia.
Is a dementia vaccine even possible?
Researchers are now looking at the possibility of protecting a person from developing dementia through a vaccine.
Traditional vaccines, such as vaccines for the flu and shingles, train the body’s immune system to fight off specific viral infections.
“More and more, there’s an appreciation of the immune system being relevant in the central nervous system, both in terms of driving a disease state, but also potentially recovering from or even preventing a disease from happening, including something as complex and devastating as dementia,” said Dr. David A. Merrill, a psychiatrist, and director of the Pacific Neuroscience Institute’s Pacific Brain Health Center at Providence Saint John’s Health Center in Santa Monica, CA.
He gave the example of recent evidence showing a person getting the flu or pneumonia vaccine might decrease their risk of developing dementia.
“It’s spurring the idea ‘could immune system activation or support actually help stave off the dementing process or nerve degenerative disease process?’,” Dr. Merrill continued.
“The starting point of the theories or hypotheses about Alzheimer’s didn’t start with ideas about the immune system, but it’s ending up that perhaps the treatments can and should involve helping or addressing immune system function with aging,” he told us.
What would a dementia vaccine do?
According to Dr. Michael G. Agadjanyan, vice president and professor of immunology at The Institute for Molecular Medicine in Huntington Beach, CA, vaccines against neurodegenerative disordersTrusted Source are like subunit vaccinesTrusted Source — using only a piece of the pathogen — and recombinant vaccinesTrusted Source using DNA technology to raise antibodies against the most immunogenic peptide segments.
Dr. Heather Snyder, vice president of medical and scientific relations for the Alzheimer’s Association, said it is an exciting time in Alzheimer’s disease research, with over 100 potential therapies being tested at various stages of the research process, and many more being developed.
“There has been some research exploring active immunization, such as vaccines, to ‘protect’ individuals from Alzheimer’s,” she detailed. “These are vaccines that are being developed to target the biology related to Alzheimer’s.”
“They are, in some cases, leveraging the biology of decades of vaccine-related development more broadly in medical care. There are also different types of delivery systems and different types of biology that may be targeted with a vaccine for a potential therapy,” she explained.
Dr. Agadjanyan explained that dementia vaccines would generate immune responses against pathological molecules in the body associated with dementia, including:
beta-amyloidTrusted Source proteins — toxic build-up of these proteins in the brain is often linked to Alzheimer’s disease
tauTrusted Source — a protein that helps stabilize the internal structure of neurons in the brain; abnormal tangles of tau protein in the brain are associated with Alzheimer’s disease
alpha-synucleinTrusted Source — a protein in neurons associated with Parkinson’s disease and Lewy body dementia when large amounts accumulate.
“In Alzheimer’s disease, the following processes develop in the brain tissues,” Dr. Agadjanyan explained to Medical News Today.
“[Beta-amyloid] plaques are formed from beta-amyloid protein. Inside the neurons of the brain, neurofibrillary tangles are formed from hyperphosphorylated tau protein. These accumulations of beta-amyloid and tau protein lead to the destruction of neurons and the development of inflammatory processes,” he said.
“As a result, neurons and the connections between them vanish, and memories, the ability to create them, and other human cognitive functions — thinking, the ability to concentrate on a task, logic, etc. — go with them,” he continued. “After a person receives a diagnosis of Alzheimer’s disease, they rarely manage to spend more than five to seven years in this world.”
Dr. Agadjanyan said that current scientific data suggest that aggregation of beta-amyloid is the critical feature for initiating Alzheimer’s disease followed by accumulation of pathological tau and, downstream, inflammation, oxidative stress, and neurodegeneration.
When will a dementia vaccine be available?
Dr. Merrill predicted it will be a while before any vaccines are available to the public.
“It’s still going to be a number of years before any vaccine is able to get through the development process, the regulatory hurdles, [and] the phases of clinical trials,” he pointed out.
Dr. Snyder agreed, and stated that the studies to date have been very small or in mice.
“More research in large, diverse human populations are needed before we can comment on the potential usefulness of a vaccine for protecting against or treating Alzheimer’s,” she advised.
Additionally, Dr. Merrill said people may be hesitant towards a dementia vaccine depending on how long the vaccination process may take.
“If you look at the early stage trials, the scheduling or the dosing of the vaccines can be quite variable,” he detailed. “In concept, you might hope for just a single dose vaccine and you would be protected, but the reality may be it might take a series. Monthly vaccination shots for a year is one design.”
“And the question is how interested will people be in getting this?” Dr. Merrill asked. “Clearly, if it truly protects and prevents you from getting Alzheimer’s, I think people would line up and would be very interested. But it’s all in the development of this — this is where it’s uncertain.”
