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Neurologist: The brain is complicated, largely unknown

Sharon Sha
Paul Sakuma
May 11 2020

By Paul Costello

"Memories light the corners of my mind
Misty water-colored memories of the way we were"

Remember those lyrics from that Barbra Streisand song The Way We Were?

For some people there are no misty water-colored memories -- or even memories at all. According to the Alzheimer's Association, more than 5 million Americans are living with Alzheimer's disease, which progressively destroys memory and other mental functions.

While there's no cure for the illness, Stanford neurologist Sharon Sha, MD, told me in a 1:2:1 podcast interview that there are things we can do to minimize our risk of Alzheimer's and cognitive disorders like it.

This Q&A is condensed and edited from that conversation about brain health.

As a neurologist, what intrigues you the most about the brain?

Well, I tell my kids and my patients -- and anyone else who will listen -- that the brain is the most important part of our body. Our brain helps control every other organ system. We can replace our hearts, our livers and our lungs with transplants. We can't transplant the brain.

It's the essence of who we are -- whether we are funny or serious. There's cognition and consciousness, mental and psychiatric aspects. Our brain is just so special. It's complicated and perhaps the last unknown part of the human body.

You used to believe genetics was the most determinative factor when it comes to brain health. Do you still believe that?

Our genetics, our parents -- we can't control those. We can control our diet. We can control our exercise. We can control our intellectual stimulation, our social stimulation.

There's more and more evidence to say that whatever we're born with -- or whatever fate that is set for us -- we can modify that with certain lifestyle modifications like exercise, a Mediterranean diet and keeping our brain active and healthy.

We know that food is fuel for our body; it's also fuel for our brain. The Mediterranean diet can be helpful for slowing down progression of cognitive impairment related to Alzheimer's disease. We still don't know what it is in the diet that makes it healthy -- leafy greens, fish or fish oils, nuts -- whatever it is, the components or some part of the diet could be helpful.

For Alzheimer's, we also know there are genetic risk factors, like having a genetic mutation or having amyloid, one of the proteins that we see in Alzheimer's disease. Yet, we can attenuate -- or reduce -- that increased risk for developing Alzheimer's disease with exercise.

Why is exercise an important part of keeping the brain healthy?

As a behavioral neurologist who sees a lot of patients with Alzheimer's disease, I think a lot about how exercise can help our memory and our cognitive functions.

We don't know how it works, but we know that it is effective. Whether it's fast walking, using a treadmill or riding a recumbent bike, aerobic exercise is really good for our brain function.

Healthy older adults who exercise are less likely to have atrophy than those who don't exercise.

Why do women have a higher risk for Alzheimer's than men?

We used to think there are just more women who are living longer than men, because Alzheimer's disease is more prevalent in older adults. But that's not the full answer.

One of my colleagues at Stanford, Michael Greicius, MD, PhD, (director of the Stanford Center for Memory Disorders) has been studying a genetic risk factor, ApoE4. If you have that, you are at greater risk for developing Alzheimer's Disease. He found that women with ApoE4 are more likely to develop Alzheimer's disease than men with ApoE4. We don't know if that's the entirety of why women tend to have Alzheimer's disease versus men, but that could be part of it. For some reason, ApoE4 affects women more than it affects men.

Most clinical trials and research on Alzheimer's disease often lumps everybody together in one big group. We really need to segregate out the gender, demographic and socioeconomic differences -- and genetic things that we haven't yet learned about -- to really segregate out who's at risk and why, and to understand the heterogeneity of Alzheimer's disease.

Why did you choose neurology as a specialty?

The brain is so fascinating. When it doesn't work right, it really changes our ability to function and interact with the external world. Even if I don't have a cure, I can educate and help patients and their families navigate what they're dealing with. That helps me feel like I'm doing something for them and for society.