By: Melissa Tanner, Ph.D.
From a young age we are taught that we are each as special and distinctive as a snowflake; no two are alike. It is only later, as we begin to study biology and genetics, that we learn how truly similar we all are. 99.5% of human DNA is shared, meaning that only 0.5% of your DNA accounts for all the differences, or genetic variants, that make you unique. Direct-to-consumer (DTC) home genetic testing kits have created a booming industry out of analyzing the 0.5% of your genome that is distinct and sharing those results with you for fees ranging from $79 to $ 199. You simply collect a swab of saliva, mail the swab to a lab, and wait a few weeks for a report. Most of the information that is shared is personally meaningful but benign. For example, DTC kits can help you clarify the region of the world your DNA originates from or the migratory patterns of your ancestors. Kits can also offer scientific justification for certain traits, such as how likely you are to consume more caffeine than the average person or how likely it is that you will be able to match a musical pitch. These results may have a positive impact on your physical or psychological well-being in that they may cause you to monitor your caffeine intake more closely—and cut back, if necessary—or encourage you to pursue a hobby that is well-suited to your innate abilities and, therefore, more likely to bring you joy. If, by chance, the test says that you are not likely to be able to match a musical pitch, but you can, then you can take pride in beating the odds. No harm done.
The same cannot be said for genetic tests that assess for health risks. There are very few traits or diseases that are controlled by genes alone, and, in most cases, the role that genes play in disease development is over-estimated. Genetic tests that do a “data dump,” meaning they reveal the presence of a gene or mutation without adequate interpretation or access to support, can do great harm. Take late-onset Alzheimer’s disease (AD) for an example, as it is one of the 10 diseases highlighted in the Genetic Health Risk (GHR) report provided 23andMe, one of the most popular DTC kits. The test explores the versions, or alleles, of the APOE gene that a person has inherited, with one or two e4 variants indicating heightened risk for development of late-onset AD. A positive result, meaning that the presence of one or two e4 variants is revealed, may lead to the assumption that AD is a foregone conclusion, which could cause the person to panic and stop looking for strategies to aid with disease prevention or risk reduction. Panic is especially likely with genetic testing for conditions like AD that lack a disease-modifying treatment. Imagine being a passenger on a ship that you know to be insufficiently equipped with life preservers. Now imagine finding out that the ship has hit an iceberg and is, with certainty, going to sink. This is akin to the panic that might ensue when you find out that you have one or two e4 variants, knowing that there is no “cure” for AD.
The difference with genetic testing for AD is that, even with a positive result, you do not know for sure that the ship is going to sink, and you may be able to steer the ship off course before it even hits the iceberg. In other words, it is important to remember that genes are only one factor influencing the onset and progression of dementia. Inheriting one or two copies of APOE variant 4 DOES NOT mean that AD is inevitable. Conversely, inheriting 2 copies of the e2 or e3 variants of the gene DOES NOT mean that AD is ruled out. Lifestyle habits and environmental factors also play a role in the development of AD. Think of AD as the final destination of a train. Genes, habits, and environmental factors all play a role in determining whether the tracks are laid for this particular train route. Once the tracks are laid, the train cannot be stopped, but the progression or speed of development can be slowed.
In the spirit of prevention, slowing rate of decline, and mitigating risk of dementia, The BCAT® Research Center developed the ENRICH® program, which emphasizes the practice of brain-healthy habits. Scientific literature on dementia suggests that there are several modifiable risk factors for AD and related dementias. We translated these modifiable risk factors into 6 behavioral recommendations: Exercise daily, No smoking, Routine cognitive stimulation, mood Improvement (especially for depression), hypertension Control, and maintenance of Health weight and body fats. One easy way to remember to practice these brain-healthy behaviors is to use this acronym:
Routinely add Cognitive Stimulation
Improve Mood (Do not let depression go untreated)
Healthy Weights and Body Fats
Returning to the issue of DTC genetic testing kits, in April of 2017 the FDA reversed their 2013 ban, authorizing 23andMe to market GHR tests for 10 diseases or conditions, including AD. Given that these tests are now readily available to consumers, it is even more critical to remember that genetic risk is only one piece of the puzzle. A “positive result” does not mean that AD is inevitable. A “negative result” does not mean that one should ignore preventative measures. Preventative measures are particularly valuable given that there is currently no disease-modifying treatment. When it comes to AD and other dementias, it is important to be an informed consumer and proactive with respect to your health. Regardless of whether you decide to pursue DTC genetic testing, there are actionable steps, such as those outlined in ENRICH®, that can reduce your risk of developing AD and other dementias. To see how you are doing with respect to these modifiable habits and learn ways to lower your risk, visit our website at www.enrichvisits.com.