My grandmother and great-grandmother both spent their last years ravaged by late-stage Alzheimer’s disease — or, as they called it at the time, senile dementia.
When I decided to undergo genetic testing, the response from my family was mixed at best. After all, why did I want to know whether or not I carried the Alzheimer’s gene? Like most people, their view of the disease was bleak and fatalistic.
They even joke about wrapping a cyanide tablet in a small box and exchanging it at Christmastime. The logic here is that when someone in the family forgets what it’s for, they should then kill themselves with the pill.
Horrible? Yes. But utterly emblematic of the stigma and fear they feel at the thought of getting Alzheimer’s…as if they’d be better off dead.
Not one to shy away from a challenge, I spit into a tube and sent it off to 23andme.
A few weeks later, their fears were somewhat confirmed: I do, indeed, carry one variant of the APOE gene that is associated with a higher-than-average risk of dementia.
Does this mean that my fate is sealed? Not at all.
Variants Are Different Than Mutations
Genetic mutations are changes in the nucleotide sequence at the DNA level. They are inherited and — until CRISPR is perfected and widely used — permanent. In other words, you can’t do anything about it.
On the other hand, variants occur at the gene or allele level. Like mutations, variants can be hereditary. The main difference is that mutations are static, fixed and often detrimental to the individual carrying them while variants are simply the differences that make us unique.
We Are Not Defined By Genes Alone
Imagine if you will, identical twin sisters who are born with a genetic variant that causes their bodies to absorb fat at twice the normal rate. One sister leads a healthy lifestyle: she exercises and eats well throughout her life. The other sister does not lead a healthy lifestyle: she is sedentary, never exercises and eats like crap.
One sister ends up morbidly obese while the other maintains a normal weight throughout the course of her life. Why is this?
Both sisters entered the world with the same genetic profile, also known as genotype. By applying different environmental pressures, each sister caused their genotype to express differently, thus resulting in distinct phenotypes.
The sister who ate well, exercised and stayed thin did so because the gene that caused her to absorb fat at twice the normal rate never switched on. Conversely, the sister who ate junk food and sat on the couch all day flipped that fat absorption gene into the On position. Rather than repressing that gene, she activated it.
People who do not carry a genetic risk for Alzheimer’s can still develop the disease. And people who have risk-associated variants of the APOE gene do not always develop Alzheimer’s. While it is a risk factor, it is not necessarily the deciding factor.
Knowledge Is Power
When Angelina Jolie decided to have her ovaries and fallopian tubes removed as well as undergo a prophylactic double mastectomy, she did so to reduce her risk of developing the same type of cancer that killed her mother.
With the Alzheimer’s gene, it’s not so clear-cut since you can’t remove your brain because it might get sick later in life.
But there are other ways to reduce the risk. In his blockbuster book, The End of Alzheimer’s, Dr. Dale Bredesen provides a roadmap that we can all use: eliminate chronic inflammation; optimize hormones and other trophic factors; and avoid environmental toxins.
Because of my APOE status, I have a higher-than-average risk of developing Alzheimer’s. Therefore, I make conscious lifestyle choices to counteract this risk. In other words, I stack the deck in my favor and let the cards fall where they may.