Genetic Risk and Alzheimer’s Disease: Should You Worry?

Genetic risk and Alzheimer’s disease: Should you worry?

Alzheimer’s disease is now so common that almost all of us have experienced a family member slowly succumb to the condition. Could this also happen to you?

Alzheimer’s disease or normal aging?

Alzheimer’s disease is the most common of all dementias. A devastating, slowly progressive brain disease, it is characterized by severe memory loss. In the past, becoming “senile” was seen as just another part of the aging process. Now we know better. Alzheimer’s disease, like diabetes or heart disease, is a chronic condition that has both genetic (inherited) and nongenetic causes.

Is Alzheimer’s disease genetic?

Alzheimers

Without looking at genetics or other specific levels of risk, the overall baseline risk of getting Alzheimer’s disease is about 10 to 15 percent. Around 15 to 30 percent of people with Alzheimer’s have a first-degree relative (a parent or sibling) with the disease, and about 75 percent of cases have no family history of it at all. Only about 5 percent of all Alzheimer’s cases are due to an autosomal-dominant gene (i.e., a gene that causes Alzheimer’s disease in everyone who inherits it).

Most people with Alzheimer’s have what is called late-onset Alzheimer’s disease. This most common form of dementia affects 95 percent of people with the disease. There is no known single gene attributed to late-onset Alzheimer’s disease.

Researchers have identified susceptibility genes that confer relative likelihood of late-onset Alzheimer’s – but not certainty. The main susceptibility gene is the apolipoprotein E gene (APOE), which is involved in lipid transport and cholesterol function. One of the three forms of this gene, the APOE ε4 allele, is associated with a 50 to 55 percent increase in lifetime risk of Alzheimer’s disease when two copies of the ε4 allele are present. This means that some people without the APOE ε4 gene develop Alzheimer’s disease and some people with it never develop the disease at all.

In contrast, young- or early-onset Alzheimer’s disease (Alzheimer’s occurring before the age of 60) has a direct genetic cause. However, early-onset Alzheimer’s disease is quite rare compared to the late-onset form.

Misdiagnosing Alzheimer’s disease

Because autopsy is the only way to confirm the diagnosis, about 30 to 50 percent of people diagnosed with Alzheimer’s are found to have another dementia altogether upon examination. Most misdiagnosed cases have potentially preventable forms of dementia caused by small vessel disease of the brain or by vascular dementia. These conditions are mainly caused by poor cardiovascular health that damages the blood vessels of the brain. High cholesterol, diabetes, heart disease, smoking and high blood pressure are all major risk factors for small vessel disease and vascular dementia.

Other dementia types can also be misclassified as Alzheimer’s disease, such as the dementia associated with Parkinson’s or rarer dementias involving the frontal lobes. When evaluating genetic risk, this misclassification matters. If you have a relative with Alzheimer’s disease, you may think you are also at risk for developing the disease, but in fact there is no guarantee that your relative’s diagnosis is definitive unless it is confirmed by autopsy.

Should I consider genetic testing for Alzheimer’s disease?

Regarding late-onset Alzheimer’s disease, genetic testing can certainly tell you whether you have the genes that carry an increased risk but won’t tell you conclusively whether you will or will not develop the disease. Late-onset Alzheimer’s disease is difficult to predict, as your risk is influenced not only by genetics, but also lifestyle and environmental factors. Risk of susceptibility increases most markedly with age, regardless of genetics, with the highest likelihood found in those over 85. For this reason, genetic testing is best considered in early-onset disease, where genes play a larger role.

Preventing late-onset Alzheimer’s disease

Even with a high genetic risk, you can reduce your overall chance of cognitive decline. Lifestyle choices can increase or decrease the likelihood that a genetic risk for Alzheimer’s will express itself during your lifetime or if you will experience cognitive decline regardless of genetic risk. This means that you may be able to decrease – or, conversely, increase – your risk by modifying your activity level, diet, sleep and overall health.

7 tips to help reduce the risk of late-onset Alzheimer’s disease

1. GET MOVING. A lack of exercise is known to increase the risk of cognitive decline and Alzheimer’s disease. Consult with your kinesiologist on a fitness plan that’s right for you.

2. GET ENOUGH SLEEP. Sleep deprivation may increase your risk of Alzheimer’s disease. Most adults need 7 to 9 hours of sleep per night.

3. EAT WELL. A poor diet can contribute to several brain health risk factors. Try to avoid eating processed, high-sugar and high-salt foods.

4. AVOID BAD HEALTH HABITS SUCH AS SMOKING AND EXCESS DRINKING.

5. MANAGE CHRONIC STRESS. When stress persists over time, it can cause vascular changes and chemical imbalances that can damage your brain. Manage stress to improve your brain health and reduce your Alzheimer’s risk.

6. PROMOTE COGNITIVE STIMULATION. Encouraging mental stimulation by learning new things and challenging your brain throughout life can reduce your risk of developing Alzheimer’s.

7. KNOW YOUR HEALTH NUMBERS. Do you know your blood pressure, blood lipid or cholesterol levels and body mass index? These numbers give you a direct idea of your personal risk of cognitive decline over time; the worse these numbers, the higher the risk. If the numbers are not great, work with your Copeman team to get them back in line.

The bottom line

Making brain-healthy choices every day can reduce your chances of cognitive decline, no matter what your genetic risk is. Today is always the best day to start changing your behavior and making your brain health a priority.

Concerned about your memory or overall cognitive skills? Please contact your nearest Copeman Healthcare Centre to book an appointment with the brain health team. Let us create a plan to ensure your optimal brain health.