Preventing Cognitive Decline and Dementia: A Way Forward

By John Anders, May 10, 2019

People are living much longer. And a common consequence of aging is loss of thinking skills. There’s no clear line between what’s sort of normal loss of thinking skills and disease.

And being able to systematically study that, makes it a little bit more challenging. There’s a great amount of noise, a great amount of misunderstanding out in the world, about what the causes are of dementia and more importantly what you can do to prevent it. In 2015, 4 to 5 million adults in the U.S.


were suffering from dementia, costing more than $200 billion dollars. As the population grows and people live longer, the number of people with dementia will increase.

When people become impaired, it doesn’t just affect them, it affects everybody around them. Their families have to take care of them. This has enormous effects on the whole society in ways that lots of other diseases don’t.

The National Institute on Aging at NIH asked the National Academies to convene a committee of experts to evaluate the latest research on how to protect cognitive health. The committee looked at studies on three types of conditions.

Age related cognitive decline, which can be a normal part of aging. Mild cognitive impairment, in which a person shows more notable problems but can adapt and live independently. And clinical Alzheimer’s-type dementia, in which someone can no longer function independently.

This includes Alzheimer’s disease, which is the leading cause of dementia, and other diseases with similar symptoms. When people are developing mild problems, we ask about things like how often they’re forgetting appointments, how often they’re misplacing things, how often they have trouble paying their bills.

When a disease progresses to the point where someone has dementia, then the forgetting is not mild like that anymore. Then people have trouble remembering something from minute to minute. And sometimes second to second.

Cognitive decline and dementia progress slowly, and damage in the brain often begins a decade or more before any symptoms show up. For a while the brain can adapt, which can mask the early stages of the disease. But by the time someone starts exhibiting symptoms, damage in the brain could be extensive.

So, long before someone has trouble remembering names, or getting lost riding in a car, there will have been detectable changes in the brain, that then progress and lead to dementia.

Researchers are actively investigating treatments for dementia, but the best possible solution is to prevent the disease altogether. When nerve cells die in the brain, we don’t have any way of rejuvenating them.

The notion is that if you can intervene really early, then you might be able to prevent that process. Through their review, the National Academies committee did not find any interventions that were shown to definitively prevent cognitive decline or dementia.

The committee did identify 3 interventions where the evidence was “encouraging but inconclusive.” « Encouraging but inconclusive evidence, » and those words are important. If you engage in these three activities, which by the way, are good for you anyway, then at a minimum, we can say [that] they might help.

One intervention is cognitive training, which includes an array of exercises aimed at enhancing problem solving, memory, and speed  of processing. 

Many people assume that that cognitive training means computer-based brain games. It’s a much more complicated intervention than just sitting at the computer by yourself. There is no evidence, in fact, that the computer-based brain games actually make a difference.

A second intervention is managing high blood pressure in people with hypertension. This could be accomplished through taking blood pressure management medications, and sometimes through lifestyle interventions such as diet and exercise.

Several studies show a connection between controlling high blood pressure in mid-life and reduced risk of dementia later.

Hypertension is an insidious disease. Many people who are hypertensive don’t know it. What’s important is that you don’t try to control it in someone who is 70 for the first time but it needs to be done in middle age because that’s when the brain changes.

A third intervention is being physically active; for example, increasing aerobic exercise and strength training. That just means doing more than what you currently do. It doesn’t mean going out to join a gym, or to start doing weight-lifting, or anything like that.

It just means that if you are a person who’s pretty sedentary, then you can start by just simply walking.

We know that over short periods of time, in clinical trials, physical activity actually appears to show cognitive benefit. We also know that there are changes in the brain that we can measure, like on magnetic resonance imaging scans.

Managing your blood pressure, physical exercise is good for you. Cognitive training won’t hurt you, and it looks like it may help you. To know for sure if these interventions prevent cognitive decline and dementia, more research is needed.

The National Academies committee also recommends a number of ways to improve future studies. One area of focus is enhancing our ability to understand and predict disease progression.

We might be using a scan of some sort that tells us about the structure of the brain, that tells us about the proteins in the brain; To try to get a really good prediction of what’s going to happen to somebody in 10 years or in five years.

At present, a lot of research on cognitive decline and dementia falls short because studies don’t follow people for long enough or look at a broad range of the population.

You have to follow people for a very long time in order to see if you’ve made a real difference. The standard clinical trial for patients with Alzheimer’s disease might be 18 months.

For people with mild cognitive impairment it might be three years, but a lot of these changes take much longer than that to progress.

We don’t have a lot of studies that have followed people with interventions for long periods of time. We need to go out to the community and get people who don’t really come to the hospital … you know different kinds of occupations, and get them involved in research. So that we can see how these interventions work across different populations. And we want to be able to inform the public about what they can do to prevent cognitive decline and live long, healthy lives. That’s really what we care about.

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