By Sahiti Namburu, Terra Linda High School
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| Dr. Barnes |
What inspired you to focus your research specifically on Alzheimer’s disease and dementia prevention within the broader field of cognitive health?
When I started my Master's degree in public health in the late 1990's, I learned that we were expecting a large increase in the number of people living with Alzheimer's disease and dementia worldwide by the year 2050. This was very concerning because Alzheimer's and dementia are really difficult diseases to deal with for people who develop them as well as their families, and there were very few treatments and no cures. So I decided to study the epidemiology of Alzheimer's and dementia, to look at Alzheimer's and dementia using the lens of public health.
How has the field of dementia research changed since you began your work, particularly in terms of technology and the methods used to study and prevent the disease?
When I started, the focus was mainly on basic science and development of drugs and biomarkers. There are two main proteins that are affected by Alzheimer's disease — beta-amyloid and tau — and for many years there was a divide in the community regarding the "amyloid hypothesis," which posited that beta-amyloid was the key causative protein. Most of the funding went toward testing the amyloid hypothesis and developing anti-amyloid drugs. The recently approved new drugs (lecanemab and donanemab) are monoclonal antibodies that target amyloid. There also has been a push to change the definition of Alzheimer's from a disease based on symptoms (cognitive decline that affects daily life) to a disease based on biomarkers (in which case someone could have "Alzheimer's disease" if they had high amyloid levels even if they didn't have any cognitive symptoms). In my opinion, the biggest shift has been to acknowledge the potential impact of risk reduction and prevention, rather than focusing solely on drug treatments. This is more of a low-tech, public health orientation. I think this shift has occurred because the anti-amyloid drugs are effective at clearing amyloid but not very effective for treating or curing symptoms. I think people agree now that multiple approaches will be needed to really address Alzheimer's.
Based on your and others’ research, what lifestyle changes or habits have shown the most significant effect in reducing the risk of dementia?
Physical activity is consistently identified as one of the most important lifestyle behaviors to reduce dementia risk. This is because physical activity has a direct effect on the brain, bringing oxygen and nutrients through increased blood flow and stimulating the growth of new nerve cells and new connections between them (neurogenesis), and also reduces the risk of many other conditions that affect brain health including hypertension, diabetes, and depression. One of the other biggest risk factors is low education. This is particularly true in other parts of the world where educational opportunities are more limited than they are in the U.S. The 2024 Lancet Commission identifies 14 modifiable risk factors that together contribute to nearly half of Alzheimer's cases.
Is there a correlation or pattern among the factors that help prevent dementia, and could this knowledge potentially lead to a cure in the future?
There are two main ways that the risk factors are correlated with each other to impact brain health. One is related to the vascular system — or blood flow to the brain. Hypertension, diabetes, smoking, cholesterol, obesity, alcohol, physical inactivity, and air pollution can all impact the vascular system. The other is related to cognitive reserve — or increasing the brain's ability to function despite underlying pathology such as amyloid and tau. Low education, hearing loss, vision loss, social isolation, physical inactivity, and head injury can all reduce cognitive reserve by impairing neurogenesis. As mentioned above, most of the treatments to date have focused on getting rid of amyloid in the brain. Unfortunately, although the drugs are effective at removing amyloid, they only have a small effect on symptoms of cognitive and functional decline. I do think that strategies to improve blood flow and stimulate neurogenesis have great potential cure Alzheimer's someday.
Since dementia causes memory loss, how well can people retain the memories they still have, and are there ways to help them maintain or strengthen these memories?
Yes, every time you have a thought or a memory, it reinforces and strengths that neural pathway. For this reason, people with Alzheimer's usually forget recently learned information first, while early life memories are often retained until later in the disease process. Engaging in activities that stimulate memories can have a positive impact — things like looking at old photo albums or listening to old songs together. Even movements and smells can trigger memories sometimes. It's also important to just "be in the moment" with someone who has memory loss. Even if they don't remember something or someone, they can still have an emotional response to a smiling face or a gentle touch in the moment.
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