June is National Brain Awareness Month, an excellent time to look at the current state of Alzheimer's disease and other neurodegenerative diseases. In the United States today, about 5.8 million people are living with Alzheimer's disease. By 2050, the number of people age 65 and older with AD is projected to reach 13.8 million.

The number of people living with other forms of cognitive decline, dementia, and neurodegenerative diseases is equal to those with Alzheimer's — and those numbers are projected to rise as well.

The costs of neurodegenerative diseases are staggering. In 2020, the Alzheimer's Association estimates that they will cost the nation $305 billion, rising to as high as $1.1 trillion by 2050. And that's not counting the work of the 16 million Americans who are unpaid caregivers for people with neurodegenerative disease.

Despite the human and financial costs of neurodegenerative diseases, and extensive research for a cure, we still have very few effective treatments. At this point, awareness and prevention are the best approaches.

The brain changes that happen in failing cognitive function probably begin years — possibly 20 years or longer — before symptoms such as memory changes become apparent. Because the damage occurs so slowly, it's possible that being aware of your risk and being alert to the earliest signs and symptoms can help manage the changes as they happen.

The good news is that making dietary and lifestyle changes can help prevent, slow, or even stop the process.

We know that no one specific gene directly causes neurodegenerative disease. However, we also know that having a genetic variant of the apolipoprotein E (APOE) gene does increase your risk.

The APOE gene makes a protein that helps carry cholesterol in the bloodstream. It comes in several different forms or alleles. One variant, known as APOE4, increases your risk of dementia. Approximately 25 to 30 percent of the population in the U.S. has this variant.

It's important to note that while APOE4 is a risk factor gene, having it doesn't necessarily mean you'll develop a neurodegenerative disease later in life — and having a different variant doesn't protect you.

However, the allele is considered an independent risk factor. So are high cholesterol and high blood pressure. Combine the APOE4 variant with high cholesterol and/or high blood pressure, and your risk of developing failing cognitive function is nearly tripled.

You can't do anything about having the allele, but you can avoid or lower high cholesterol and high blood pressure through dietary and lifestyle changes and medication if necessary.