What Causes Alzheimer’s?
As best we know, Alzheimer’s disease results from an interplay between several factors. Some of these, such as genes and family history, lie beyond our control, but we can influence others through lifestyle choices and attention to our overall health.
It is no longer true that “there is nothing we can do” to prevent or delay Alzheimer’s disease. With a proactive approach, we can shape the course of our brain health to a significant extent. It starts with understanding our risk factors.
Contact Us About Current Alzheimer’s Prevention Trials
Risk Factors for Alzheimer’s Disease
The most important Alzheimer’s risk factor is age: the older you are, the higher the risk. At age 65, 8% of people without additional risk factors are expected to have the disease. Every year the risk goes up slightly, reaching 35-50% by age 85. That said, some people never develop Alzheimer’s disease, even if they live past 100.
- Female gender: women have a higher overall risk of Alzheimer’s disease, mostly because they live longer on average.
- Family history: having first-degree relatives who have or had Alzheimer’s disease doubles the baseline risk (so if you have a 20% risk based on your age and a mother who had the disease, your risk goes up to 40%).
- Heredity: Certain rare gene mutations guarantee that you’ll eventually develop Alzheimer’s disease, while others greatly increase the risk of having it. If you have one copy of a risk-factor gene called Apo E4, for example, you have a 25-30% lifetime risk of Alzheimer’s. Having two copies bumps your risk up to about 60%.
- Traumatic head injury or repeated concussions: such incidents may speed up the onset of Alzheimer’s disease by about 5 years, though it isn’t clear whether they raise the overall risk. If you’ve experienced repeated concussions, you have an increased risk of developing Alzheimer’s.
- Low academic achievement or lack of mentally stimulating work environment: these factors reduce your “brain reserve,” which means your brain is less able to compensate for age-related decline.
- Chronic anxiety or depression: these conditions can raise levels of the stress hormone cortisol, which may damage memory-encoding structures in the hippocampus.
- Other health conditions: there is evidence that obesity, diabetes, hypertension, and cardiovascular disease (CVD) increase the risk of Alzheimer’s disease. Some autopsy studies suggest that at least 80% of people with Alzheimer’s disease also have CVD.
- Mild cognitive impairment (MCI): 17% of people with MCI progress to Alzheimer’s disease every year.
- Smoking and alcohol consumption.
Here are some factors that lower your risk of Alzheimer’s disease:
- Genetics: A few years ago, researchers discovered a gene mutation that prevents Alzheimer’s disease. The mutation lies in a gene involved in the production of amyloid, the protein clumps found in the brains of people with the disease. People with the mutation produce plaque less efficiently, making them 7.5 times more likely than others to reach age 85 without major cognitive decline.
- Nutrition: Following a diet similar to the Mediterranean diet (low in animal fat and red meat, high in fruits and vegetables) may offer some protection.
- Physical activity: In addition to enhancing blood flow to your brain, physical activity triggers the production of brain-derived neurotrophic factor, which helps your brain cells form connections. This boosts your “brain reserve” (spare brain power). While lifelong activity is ideal, even starting later in life can benefit your brain.
- Higher education or vocational achievement.
Genetic Testing for Alzheimer’s
If your mother or uncle had Alzheimer’s disease, you’re not necessarily destined to develop it yourself. In fact, genetically transmitted (familial) Alzheimer’s disease accounts for less than 5 percent of cases.
A small number of people have a “dominant” gene mutation that leads to an overproduction of beta amyloid protein in the brain. (A dominant mutation has a full impact even if inherited from just one parent.) Familial Alzheimer’s disease, also known as Autosomal Dominant Alzheimer’s disease (ADAD), generally develops before age 65.
People can also inherit risk-factor genes that increase their odds of getting Alzheimer’s disease, rather than directly causing it. The most important of these risk-factor genes is called ApoE 4. A single copy of ApoE 4 increases one’s risk of developing Alzheimer’s disease later in life by about 25-30%, while two copies raise the risk to about 60%.
As the saying goes, knowledge is power, and many individuals want to know more about their own risk factors for Alzheimer’s disease. Genetic testing can empower you to make informed choices about your brain health and open the door to participation in Alzheimer’s prevention studies. The genetic test is a simple blood test done right here at Toronto Memory Program. To help you decide about testing, a specialist who understands your unique situation will discuss the risks and benefits of obtaining genetic information with you.
When genetic test results reveal an increased risk of developing Alzheimer’s disease, you have several options to consider. We offer:
- Closer monitoring with more frequent memory testing
- Systematic lifestyle modifications to optimize brain reserve
- Participation in prevention studies for individuals at risk but without symptoms
- Participation in treatment studies for individuals with symptoms of early-onset Alzheimer’s disease
Consider genetic testing for Alzheimer’s disease if one or more of your close relatives developed the disease – particularly if these individuals span two or more generations or their symptoms began before age 65. (Regardless of cause, Alzheimer’s disease that begins before age 65 is considered “early-onset” Alzheimer’s disease.) Get in touch with us so we can arrange for a counselling session and answer your questions about whether genetic testing makes sense for you.
Know Your Risk Factors For Alzheimer’s Disease: Get an Assessment
If you are concerned (or simply curious) about your Alzheimer’s disease risk factors, you can arrange for a risk assessment at Toronto Memory Program. We will take a careful look at your personal and family history, evaluate your memory, and compile the information into an overall risk profile. Once you know your Alzheimer’s disease risk factors, you can take steps to preserve your brain health.
Trust Your Gut
Many people suspect they have memory problems before getting tested or diagnosed. Even if they get tested and score in the normal range, their perceptions may be correct: some memory changes are too subtle for most tests to detect. For instance, a person may notice she needs to search a little longer for words or rely more on the calendar to remember people’s birthdays. Some Alzheimer’s disease clinical trials are designed especially for this group of people. If you suspect your memory is not what it used to be, consider an assessment.