Over the past few years, I have been talking about the risk factors associated with developing dementia. Dementia is not a part of normal aging, and we have real power in changing our brains. There have been a lot of misconceptions that dementia was primarily caused by genetics – if your grandmother had dementia or Alzheimer’s, you probably were going to get it too. I loved breaking that myth. What are the risks of developing dementia as you get older? Simply, 70% of the risk is due to lifestyle; 30% of the risk is due to genetics and environment. This can be a little confusing, so I am going to divide the topics into a couple of different articles. This introductory article will cover the breakdown of lifestyle, genetics, and environment, as non-modifiable and modifiable risk factors. The largest piece of this puzzle will be Lifestyle. So, it will get an article to itself. Trust me, this puzzle will be complete when I am through!
If My Grandmother Had Dementia, Am I Going to Get It Too?
One of the biggest fears I encounter when I talk to aging boomers is their likelihood of getting dementia. It is scary, especially if you have seen it up close and personal. When I mention that genetics plays an undersized role in developing dementia, they are relieved but also confused. Let’s clear that up!
The unraveling of the genome has revealed important information about the genesis of certain diseases. There are two categories of genes I want to introduce:
Deterministic Genes
· These genes directly cause a disease, guaranteeing that anyone who inherits one will develop a disorder.
· These genes are considered non-modifiable. This means that the disease caused by these genes cannot be avoided.
· There are three genes directly responsible for the development of early-onset dementia.
o The APP Gene: the amyloid B-protein precursor (APP) on chromosome 21.
o Presenilin 1 (PS1): chromosome 14
o Presenilin 2 (PS2): chromosome 1
· If a person has an alteration in any of these genes, they will almost certainly develop familial Alzheimer’s disease.
· If a parent has any of these faulty genes, their children have a 50% chance of inheriting the disease
Risk Genes
· These genes increase the likelihood of developing a disease
· APOE 4 was the first risk factor identified and remains the gene with the strongest impact on risk for developing Alzheimer’s disease.
· There are 17 genes associated with Alzheimer’s disease that are risk factor genes.
o This means that they increase the risk, but do not guarantee the person will develop Alzheimer’s disease.
The Role of Environment as a Risk for Developing Dementia
The evidence is starting to pile up that air pollution and other environmental factors increase the risk of developing dementia. Numerous research studies have determined that air pollution can cause inflammation and damage to the vascular system, but the results of the study also demonstrated that air pollution can actually cause brain damage! Particles in the ambient air are an environmental neurotoxin to the aging brain. It is estimated that those living close to busy roads have a higher risk of dementia because they can be exposed to higher levels of air pollution from vehicle emissions.
Upon closer examination of the research, I discovered how vulnerable our brains were to other environmental factors that are placing us at risk for dementia.
There are two periods in our life when our brain is most vulnerable to environmental toxins – during fetal development and in older age. There have been an increased number of studies over the past ten years that have looked at low-level lead exposures on adult cognitive abilities later in life. Lead accumulates in our bones but can be mobilized over time as part of the aging process. Think back to our younger days: there was lead in gasoline, lead in paint, and lead pipes that made up our plumbing systems.
· Alzheimer’s is perceived to be an aging disease with most diagnoses coming to those 65 and over. Metals, including aluminum, zinc, copper, and lead have been linked to inducing plaques causing neurodegeneration in the brain.
· Parkinson’s disease: Risk factors for PD include exposures to pesticides, metals, and solvents. Amyotrophic Lateral Sclerosis (ALS): Characterized by degeneration of lower motor neurons in the brainstem and ventral horn of the spinal cord.
The Lifestyle Risk Factors that Influence Dementia
There are two kinds of lifestyle risk factors:
Non-Modifiable Risk Factors
These risk factors cannot be avoided:
· Age: dementia is not a normal part of aging, but age is the strongest known risk factor for developing dementia. A person who is aged over 75 is more likely to develop dementia than someone under age 75.
· Sex: Women are at a higher risk of developing Alzheimer’s disease than men
o Women (on average) live longer than men
o Changes in estrogen level over a women’s lifetime
o Presence of frailty and other health conditions
· Genetics: Although the role of genetics in the development of dementia is not fully under, scientists have found over 20 genes that may increase the risk of developing Alzheimer’s disease
Modifiable Risk Factors
These genes increase the risk but do not guarantee the person will develop Alzheimer’s.
· Lifestyle Choices
o Your brain does not how old you are but rather by the lifestyle that you lead.
o Poor lifestyle choices can accelerate brain aging, meaning that you lose cell volume faster.
I will elaborate on each of the following lifestyle choices in my next article. Here is a list of what I will be covering.
· Smoking
· Chronic Alcohol Use
· Low Levels of Cognitive Engagement
· Obesity and Lack of Physical Exercise
· Social Isolation
· Poor Diet
· Lack of Sleep
There are some things we have no control over and some things that we can change as we grow older and look at the possibility of Alzheimer’s disease. We will focus on what we can change and hopefully, change the trajectory of our health in our older years.
References:
Alzheimer’s Association. Is Alzheimer’s Genetic? Retrieved from https://www.alz.org/alzheimers-dementia/what-is-alzheimers/causes-and-risk-factors/genetics
Alzheimer’s Society. (June 2021). Risk factors for dementia. Retrieved from https://www.alzheimers.org.uk
Bakalar,N. (June 22, 2015). Pollution may age the brain. The New York Times. Retrieved from http://wee.blogs.nytimes.com/2015/06/22/pollution-may-age-the-brain/?_r=1&utm_source=Brain...
Blacker,D. & Tanzi,R. The Genetics of Alzheimer Disease. Retrieved from https://jamanetwork.com/
Environmental Impact on Brain Aging: Scientist Studies How Toxins Accelerate Neurodegeneration. (Spring, 2014). Aging Exchange Tracking the Way We Age: CALC Center on Aging and Life Course
Grossman,E. (September, 2014). Tie after time: environmental influences on the aging brain. Environmental Health Perspectives; 122(9). DOI:10.1289/ehp. 122-A238.
