Most Replayed Moment: Alzheimer's Starts 20 Years Before Symptoms! How To Protect Your Brain Now

**Steven Bartlett** (0:03)
What's the most compelling study you've ever encountered that proves that exercise is central to Alzheimer's prevention and brain health?

**Louisa Nicola** (0:10)
When we look at all of the data, we can see that the biggest amount of return on investment is from resistance training.

**Steven Bartlett** (0:19)
Resistance training being?

**Louisa Nicola** (0:21)
Strength training. One of the most compelling studies was probably the SMART trial where they took a group of people with mild cognitive impairment and gave them two to three times per week of resistance training.
They not only preserved their cognitive functions, they enhanced their processing speed, they enhanced their fluid intelligence, and they had slowing of the gray matter.

**Steven Bartlett** (0:44)
The gray matter?

**Louisa Nicola** (0:45)
Yeah. Your brain consists of both gray and white matter. Gray matter are the cell bodies that lives on the outer portions of your brain, and the white matter is deep within the brain, and that's where all of our myelinated neurons live. Over time, we see that we can have little lesions in the white matter of the brain.
A lot of the times people will ask me, Steven, I'm scared. My mother had Alzheimer's disease, I'm scared I'm going to get it. We were talking about genetics before. There's another genetic risk factor that we didn't talk about. The APOE4 gene is one of the strongest risk factors of getting Alzheimer's disease, but it is not a foregone conclusion that you're going to get it. So Chris Hemsworth was tested and he has two copies of this gene. So you get two copies, one from Mun, one from Dad. It's the apolipoprotein E gene. And it comes in three main variants. So you've got APOE2, APOE3 and APOE4.
So I'm a 3,3 carrier, I've been tested. And that's the general population, they're 3,3. So it doesn't raise my risk of getting the disease, but it also doesn't protect me. If you've got a copy of the APOE2 gene, it protects you against the disease. But when you have a copy of the APOE4 gene, it raises your risk by two to three times.
If you have two copies of the gene, it raises your risk by 10 times. If you are a male, here's the devastating thing. If you are a female with one copy of the gene, you have doubled the risk than your male counterpart. So one copy of the gene of APOE4 gene for a female raises your risk by about six-fold, whereas two copies raises your risk by 15-fold.

**Steven Bartlett** (2:41)
How would one go and get checked?

**Louisa Nicola** (2:43)
You can get the APOE4 gene checked out with your doctor. It's a simple blood test.

**Steven Bartlett** (2:48)
On this point of resistance training, I've heard you talk about how the legs are so important. Having strong legs.

**Louisa Nicola** (2:56)
Having strong legs is by far the most important tool in your toolbox for the prevention of Alzheimer's disease. And this was made certain to me when I read a study done on identical twins, exact same genetic profile. And they tracked them and they did cognitive tests and MRIs. And they tracked them over a 10 year period. And what they found was that the twin who possessed the greatest strength and the most leg power had a bigger brain, larger gray matter volume.
They preserved their cognitive functions. They did better on different cognitive tests.

**Steven Bartlett** (3:40)
Why is resistance training increasing the size of my brain?

**Louisa Nicola** (3:44)
Resistance training does so much for your brain. The first thing is we have to think about the journey that we're going on, right? So when you look at all of the studies, I want to make it really clear. All of the studies show that in order to produce the neural effects of resistance training, you need to be lifting at around 80% of your one repetition max.
So 80% of one RM. So that's quite heavy.
There is so much controversy on social media right now. Should I lift heavy? Should I lift light? And when it comes to hypertrophy alone, so increase in muscle mass, muscle cell size, you can get there.
Men can get there. Women can get there by lifting light, high reps. Or you can get there by lifting heavy and low reps. It just depends on who you are and how much time you have. But when it comes to the brain specifically, you want to be lifting heavy for several reasons. The first one is when we lift heavy, when we literally, when we contract our muscle like this, we are releasing a whole set of chemicals. They're called myokines. And when they're released from the muscle, they go up to the brain and they do beneficial things for our cognitive performance, our cognition. And they help with the growth and proliferation of new neurons in the hippocampus.