Most of us experience temporary lapses of memory, like misplacing our keys or forgetting where we parked. While such absentmindedness is a widely experienced phenomenon and is considered a normal part of aging, in some cases memory loss and other cognitive deficits can be early symptoms of Alzheimer’s disease.

This poses an important question: Is there anything we can do to boost brain health and prevent cognitive decline? To learn more, we spoke with Sharon J. Sha, MD, medical director of the Stanford Neuroscience Clinical Trials Group, clinical core co-leader of the Stanford Alzheimer’s Disease Research Center, and clinical associate professor of Neurology and Neurological Sciences at Stanford University.

Most of us are familiar with the term “mental health,” but not everyone is familiar with the concept of “brain health.” How would you define brain health as it differs from mental health?

I think mental health can be encompassed by brain health. I think of mental health as mood and mindfulness, which is an important subset of brain health. But the brain controls everything.

When I think of brain health, I think of the brain as an organ, in the same way we would think of liver health or kidney health. Brain health is determined by how the organ is functioning; how much blood flow, nutrients and oxygen it is getting; and how it is cleaning and filtering things like harmful proteins.

Whether it’s mood or cognition, I think we need to focus on what we can do to build a healthy brain.

Evidence shows that lifestyle habits (like diet and exercise) can affect our physical health. Is there evidence that lifestyle habits can improve brain health?

Definitely. There’s a good deal of emerging research on this topic, and much that can date back at least a decade. It has been shown that lifestyle habits like diet and exercise can affect our brains. As a neurologist, I look at cognitive impairment and dementia on a daily basis and I can see how important diet and exercise are for healthy aging — potentially slowing the progression of memory loss and preventing certain types of diseases such as Alzheimer’s.

What lifestyle practices have been shown to boost brain health the most?

Exercise has a very positive impact on brain health. A 2011 study found that for older adults, aerobic training increases the size of the anterior hippocampus, leading to improvements in spatial memory. Conversely, older adults who do not engage in aerobic activity experience a reduction in the size of the hippocampus (the memory center of the brain) at a rate of 1% atrophy per year.

Other studies are recapitulating the importance of exercise in minimizing, preventing or delaying the onset of memory loss and dementia. A 2019 study analyzed people who took more steps versus those who took less and how it affected the importance of amyloid protein (one of the major proteins we see in Alzheimer’s). Findings showed that those who were taking more steps had less potential decline in memory, even with high amyloid burden, versus those who didn’t take as many steps. Essentially, this is saying that exercise has the capacity to reverse the importance of amyloid proteins as a risk factor for Alzheimer’s. For this reason, I really focus on getting exercise every day. (I even leave myself reminders!)

In addition, diet can play a role in brain health. A 2011 study showed that a Mediterranean, heart-healthy diet can minimize adverse effects on memory and decrease the incidence of Alzheimer’s and dementia. There’s also a 2017 review that analyzed and compared the impact of different diets on cognition, revealing that the Mediterranean diet can be the most effective diet for memory and cognition.

Similarly, we know the negative effects on cognition of not getting an adequate quantity or high-enough quality of sleep. As I mentioned in question one, a critical component of brain health is the amount of oxygen delivered to the brain. If you’re not getting enough oxygen while you’re sleeping, perhaps because of a health condition (for example, sleep apnea), your brain function can be adversely affected. Studies show that higher quantity and quality of sleep lead to less amyloid buildup in the brain (possibly due to sleep’s filtration and clearing of that amyloid protein) and therefore a decreased risk of cognitive diseases such as Alzheimer’s.

Cognitive stimulation has also been shown to be an effective habit for preventing cognitive degeneration. Low education is a risk factor for dementia and degenerative disease, so stimulating the brain can be helpful in minimizing the risks of cognitive impairment and degenerative diseases.

What can healthy brain practices really change: mood, memory, focus?

All of the above! By engaging in preventative practices like exercise and healthy eating, memory can improve. Also, we know that when eating healthy and exercising, endorphins are released which can stimulate cognitive functioning and mood improvements.

In addition to the endorphin rush that comes with health habits like exercise, there may be other chemicals involved — and they are being studied. For example, BDNF (Brain Derived Nerve Growth Factor) — which can help memory, focus and attention — may increase as a result of physical activity.

Finally, we all know from personal experience that when we sleep better, we have improved focus and better mood. When we are sleep-deprived (as sometimes I am), we’re more cranky and have a harder time concentrating.

Thus, all these attributes (mood, memory and focus) can be improved by implementing healthy brain lifestyle habits, which of course also benefit many other organs and related health outcomes as well.

Can we expect immediate results from adopting “better brain habits”?

It depends. One day of bad sleep can be reversed quickly, but a lifetime of bad habits may be slow to reverse. You might have a sleep debt from being up all night in college that you have to pay back before you start seeing benefits.

The same thing is true if we have a lot of vascular risk factors (for example, not exercising or eating healthy). We may need to compensate for quite some time to get to a healthy level before we start receiving benefits.

We know some of the proteins that increase the risk for Alzheimer’s can start to deposit in the brain 15-20 years before the onset of symptoms. So, now is the time for prevention. Even though some habits may not show immediate results, they will make a significant difference in the long run.

If you want immediate results, exercise is one habit that tends to produce quick changes in mood and cognition; but in terms of neurodegenerative prevention, we may not see results for a while.

Are there some aspects of brain health that are “fixed” and cannot be changed? For example, if I have a strong genetic predisposition towards Alzheimer’s disease, is there anything I can do about it?

I used to tell patients, “Genetics are genetics and we can’t change that.” However, some studies now show that exercise can negate risk even if you have a genetic predisposition. Even though we can’t change genetics, healthy lifestyle habits can reduce or negate risk — even in the presence of genetic predisposition: so, let’s do what we can with these modifiable risk factors.

I often don’t order the test for genetic predisposition because it’s just a risk factor that we can’t change, and people misinterpret it as causal (i.e., develops Alzheimer’s). In other words, genetic predisposition doesn’t mean that you will get Alzheimer’s disease, and negative genetic testing doesn’t mean that you won’t.

The bottom line: focus on modifiable risk factors such as exercise, diet, sleep and education for prevention rather than worrying about genetic predisposition. Nothing is set in stone.

Are some groups of people more at risk for Alzheimer’s disease?

ApoE4 gene carriers have an increased risk. Depending on the literature you read, one copy of the gene can increase risk by 2-4 times the risk of the general population, and two copies of the gene may increase risk up to 10 times that of the general population. But that is risk, not cause.

The biggest risk factor is age. Research states that in people over age 65, 1-2% have Alzheimer’s disease. Above 85 years old, the prevalence is 30-50%. We can’t change age and we can’t change genetics, which is why I continue to emphasize those modifiable risk factors like exercise, sleep, diet, and cognitive stimulation.

There are also some topics that we haven’t studied enough. For example, women have a higher risk of Alzheimer’s than do men. Could this just be because women live longer than men? Research, however, is suggesting a more complicated theory: women may have more physiological risks than men. For example, the APOe4 gene in women appears to more often convert mild cognitive impairment to Alzheimer’s.

We also have not adequately studied Alzheimer’s disease within specific ethnic groups and races. We need more volunteers to participate in studies so we can learn more about risk and prevention.

For now, what we know is that people with genetic predisposition, low education, high age and vascular risk factors are more at risk for developing Alzheimer’s and other neurodegenerative diseases.

Where does that leave the rest of us?

I think we all need to take care of our brains — now, regardless of our age or what we were born with or what health problems we may have developed. It is never too late to start changing our lifestyle practices so that we can develop a healthy brain.

We don’t have a magic pill or cure for Alzheimer’s disease. However, emerging research points to ways we can minimize risk and slow progression. Don’t view this disease as being only about older people; rather, take preventative action now, no matter your age.

By Mia Primeau
February 2020