Your risk of dementia: Do lifestyle and genetics matter?

Globally, Alzheimer’s disease and other forms of dementia are a major burden on individuals and communities. To make matters worse, there are few treatments to combat these complex illnesses. Even the causes of dementia are widely debated. Sadly, clinical trials for drugs to stop or even slow its progress have come up short. Taking a different tack, some experts hope to intervene before people are diagnosed with dementia by encouraging lifestyle changes.

What is dementia and what makes it so complex?

Dementia describes groups of specific diseases characterized by symptoms such as memory loss. The most common type of dementia is Alzheimer’s disease (AD). People with AD have plaques in their brains made of up of tangled proteins, and many researchers have hypothesized that these plaques are the cause of the disease.

Another common type of dementia is vascular dementia. This is thought to be induced by damaged blood vessels in the brain, such as from a stroke.

Experts believe both genetic factors (variants of genes passed down from mom and dad) and modifiable lifestyle factors (diet, smoking, physical activity) all play a role in the development of dementia, perhaps in concert.

What factors might affect dementia risk?

Genes — which are not considered modifiable — and lifestyle factors like physical activity and diet — which are considered modifiable — play potential roles in different forms of dementia.

recent study in JAMA attempts to estimate how much genetic and lifestyle factors influence risk for dementia by querying individuals who pledged to be part of a UK-based “biobank.” Biobanks link large collections of biological information, such as genetics, with health and disease status gleaned from medical records. Using data in large biobanks, scientists can look at how the environment — which includes lifestyle choices — and genetics work together to increase (or decrease) risk for disease.

In the JAMA study, researchers tapped hospital records and death registries to collect diagnoses in 200,000 white British individuals age 60 or older.

But how can you measure “lifestyle” and genetic risk?

The investigators hand-picked a list of common lifestyle factors, including smoking, alcohol consumption, physical activity, and diet, and created a score. A low score denoted a “bad” lifestyle. A high score denoted a “good” lifestyle.

However, taking this approach to measure lifestyle risk has several pitfalls:

  • First, a vast number of factors comprise lifestyle and environment beyond smoking and physical activity. So any list may be arbitrary. In fact, our research team has argued that choosing a candidate list doesn’t capture our complex lifestyles and may lead to false findings. For example, what exactly constitutes a “healthy” diet?
  • Second, using a score makes the individual roles of the factors unclear.
  • Third, if connections between factors (for example, weight or history of other diseases) influence both the score and dementia, then the score might be a weak proxy for other variables that weren’t considered. In other words, if weight is associated with diet and dementia, then it is hard to untangle the association of diet.

To create the genetic risk score, the investigators used all genetic variants previously identified by a genome-wide association study (GWAS) of Alzheimer’s disease. These gene variants are strongly associated with patients who have Alzheimer’s compared with healthy controls). Using this information, the researchers constructed a polygenic risk score.

Lifestyle and genetics both play a small role in dementia

The lifestyle score was associated with dementia risk. Second, the genetic score was also associated with dementia. In other words, individuals with worse scores were at higher risk for dementia. The researchers further found that genetic risk and lifestyle appeared to act independently of each other. For example, individuals with both an unhealthy lifestyle and a high genetic risk score had almost two and a half times more risk than individuals with a low genetic score and healthy lifestyle.

However, this research was not designed to prove whether lifestyle and environment or genes cause dementia. A lot more could explain the differences between people who develop dementia. If populations at high genetic risk changed their lifestyle, and if the lifestyle was known to be the cause of AD (a big if), one out of 121 dementia cases would be prevented in 10 years. This is significant, but what number of lifestyle modifications would it take for the prevention of AD in 10, 50, or even 120 people? Do genetics even matter?

Second, the genes and lifestyle did not appear to work together — or they weren’t synergistic — in dementia risk. Specifically, this means that individuals with both bad genetic and lifestyle scores were not at risk for developing dementia any more than the sum of the parts or the individual scores alone.

New frontiers for AD prevention and treatment

New horizons for prevention and treatment might include how risk might be different for individuals of varied genetic ancestries and ethnicities (most genetic studies have predominantly focused on white individuals) both here in the US and abroad. The risk may also be different between males and females. Finally, biobanks can only describe association, not causation, between changes in lifestyle and dementia risk. To determine causation, randomized trials are required, and a new US-based randomized clinical trial called POINTER is now underway.

Trying to live a healthy lifestyle, despite its elusive definition, seems to be an obvious way to prevent dementia. What remains to be seen is how studies using biobanks can be informative about the millions of people who already may be suffering from the disease.

References

Why Most Published Research Findings Are FalsePloS Medicine, August 30, 2005.

Repurposing large health insurance claims data to estimate genetic and environmental contributions in 560 phenotypesNature Genetics, January 14, 2019.

Studying the Elusive Environment in Large ScaleJAMA, June 4, 2014.

A Nutrient-Wide Association Study on Blood PressureCirculation, November 20, 2012.

Association of Lifestyle and Genetic Risk with Incidence of DementiaJAMA, July 14, 2019.

Bible verses for today’s meditation and inspiration: Matthew E. McLaren’

Since you are precious and honored in my sight, and because I love you, I will give people in exchange for you, nations in exchange for your life. Isaiah 43:4 

However, as it is written: What no eye has seen, what no ear has heard, and what no human mind has conceived — the things God has prepared for those who love him.
1 Corinthians 2:9 

Let no debt remain outstanding, except the continuing debt to love one another, for whoever loves others has fulfilled the law. Romans 13:8

 See what great love the Father has lavished on us, that we should be called children of God! And that is what we are! The reason the world does not know us is that it did not know him. 1 John 3:1 

1 Corinthians 13:4-8  Love is patient and kind; love does not envy or boast; it is not arrogant or rude. It does not insist on its own way; it is not irritable or resentful; it does not rejoice at wrongdoing, but rejoices with the truth. Love bears all things, believes all things, hopes all things, endures all things. Love never ends. As for prophecies, they will pass away; as for tongues, they will cease; as for knowledge, it will pass away.

1 Corinthians 16:14  Let all that you do be done in love.

1 John 4:8  Anyone who does not love does not know God, because God is love.

Mark 12:29-31  Jesus answered, “The most important is, ‘Hear, O Israel: The Lord our God, the Lord is one. And you shall love the Lord your God with all your heart and with all your soul and with all your mind and with all your strength.’ The second is this: ‘You shall love your neighbor as yourself.’ There is no other commandment greater than these.”

Matthew 22:36-40  “Teacher, which is the great commandment in the Law?” And he said to him, “You shall love the Lord your God with all your heart and with all your soul and with all your mind. This is the great and first commandment. And a second is like it: You shall love your neighbor as yourself. On these two commandments depend all the Law and the Prophets.”

John 13:34-35  A new commandment I give to you, that you love one another: just as I have loved you, you also are to love one another. By this all people will know that you are my disciples, if you have love for one another.”

Colossians 3:14  And above all these put on love, which binds everything together in perfect harmony.

John 3:16  “For God so loved the world, that he gave his only Son, that whoever believes in him should not perish but have eternal life.

John 15:13  Greater love has no one than this, that someone lay down his life for his friends.

1 Peter 4:8  Above all, keep loving one another earnestly, since love covers a multitude of sins.

Recommended contacts for prayer request and Bible study

www.agapetemplesda.com

www.adventistontario.org

https://www.hopechannel.com/au/learn/courses

breathoflife.tv/

http://www.nadadventist.org/article/15/contact-us

https://3abn.org/all-streams/3abn.html

https://www.adventist.org/en/utility/contact/

It Is Written


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