Is Alzheimer’s Disease Genetic? (It’s Complicated)

According to the Alzheimer's Association, more than 6.7 million Americans live with Alzheimer's disease, the most common form of dementia. Alzheimer's is characterized by symptoms like wandering and disorientation in the early stages before progressing to more severe symptoms like an inability to communicate, difficulty swallowing, and seizures. Given the toll this condition takes on families and the US healthcare system, it's no surprise that plenty of research focuses on ways to prevent Alzheimer's, what causes it, and more. Crucially, many hope to answer the question: Is Alzheimer's disease genetic?

The answer, unfortunately, is complicated

Like many other conditions, family history plays a role in risk for Alzheimer's. Specifically, Alzheimer's disease risk increases if close family members have the condition. And, thanks to decades of research, we know more about this condition than ever before—including just what heritable traits put someone at risk.

Many of the symptoms of this condition are caused by amyloid plaque buildup and tau tangles (types of proteins) in the brain. According to recent research, different heritable high-risk genes and rare genetic variants (mutations) of them could make someone more likely to develop these hallmark plaques and tangles in the brain, including:

• APOE4/Apolipoprotein E-e4 - Having 2 copies of this APOE gene could lead to an increased risk of lipid (fatty acid) imbalances in the brain, which could in turn lead to amyloid plaque buildup.
• Amyloid precursor protein/amyloid beta precursor protein (APP) - Present on chromosome 21, genetic variations of APP could lead to an increased risk of early-onset Alzheimer's disease.
• Presenilin 1 (PSEN1) - Present on chromosome 14, experts associate mutations in PSEN1 with early-onset Alzheimer's.
• Presenilin 2 (PSEN2) - Present on chromosome 1, mutations in PSEN2 are also associated with early-onset Alzheimer's.

While these genes might sound scary at first, it's important to note that presence of these genes/genetic variants does not necessarily mean that someone will develop dementia.

More than just genes can lead to increased risk of Alzheimer's disease; lifestyle and environmental factors also play a critical role in its development.

Other factors that can lead to a higher risk of developing dementia include:

• Lifestyle factors - Smoking, drinking, and leading a sedentary lifestyle can all increase the risk of this condition.
• Environmental exposures - Long-term exposure to toxic chemicals or substances like lead can lead to increased risk of conditions like ALS, Parkinson's disease, and Alzheimer's.
• Pre-existing medical conditions - Experts often associate depression, cancer, and other conditions with increased Alzheimer's risk.
• Down syndrome - An estimated 50%+ of people with Down syndrome will develop Alzheimer's later in life due to having an extra copy of chromosome 21. This type of Alzheimer's, however, is not heritable.

While we cannot control our genetics and family history, we can control many of the risk factors for developing Alzheimer's. Even better, even if someone is diagnosed with Alzheimer's or another form of dementia, there are several methods to mitigate its effects, including:

• Physical therapy
• Physical activity, including both strength-training and cardio exercises
• Engagement with others, as loneliness can lead to an increased risk of dementia
• Activities to stay mentally sharp
• Taking the right vitamins, if necessary
• Eating a healthy diet
• Maintaining healthy cholesterol levels
• Maintain healthy blood pressure levels, as elevated blood pressure can increase the risk of vascular dementia along with other types of dementia
• Knowing the signs and symptoms of different forms of dementia, so you or your loved one can seek proper care right away.
• Visiting a genetic counselor/undergoing genetic testing to determine your genetic risk
• Participating in clinical trials to increase experts' understanding of this condition

A loved one receiving a dementia diagnosis can be overwhelming, but it doesn't have to mean that there is no hope. Receiving the right type of care early on can mean enjoying several more months or even years with your loved one. At St. Andrew's, our memory care team—composed of compassionate professional caregivers, chefs, housekeepers, and more—works with each family to develop the right care plan for each individual who comes through our doors.

Contact us to learn more about how we can care for your loved one experiencing memory loss and cognitive decline.