Published March 02, 2023
Chris Hemsworth, the Australian actor perhaps best known for his role as Marvel Comics superhero Thor, recently made the news for a more personal reason: his DNA results. While filming a new docuseries about health and aging, the 39-year-old actor discovered that he has two copies of a gene variant (APOEe4) that is linked to an increased risk of developing Alzheimer’s disease after the age of 65. His story has many people asking themselves, “Should I have my genes tested, too?”
According to experts at Yale New Haven Health, the answer is: It depends – but that’s probably not the first thing you should do.
“Alzheimer’s disease is just one type of the conditions that present with dementia,” said Anna Szekely, MD, a neurologist and geneticist at Yale New Haven Hospital who leads the Yale Neurogenetics Clinic in the Department of Neurology at Yale School of Medicine.
Dementia is used to describe a group of symptoms that affect memory, thinking and social abilities severely enough to impact a person's ability to carry out daily activities. Having memory loss alone doesn't mean you have dementia, although it can be an early sign.
While Alzheimer's disease is the most common cause of a progressive dementia in older adults, there are other causes of dementia with similar features. It’s also important to note that only a small fraction of progressive dementias are hereditary. Dr. Szekely said physicians and patients must consider several factors before proceeding with genetic testing: the dementia symptoms, how old you are when the symptoms begin and your family history.
“For Alzheimer’s disease and other progressive dementias, we call it ‘early-onset’ if the symptoms begin before the age of 60-65. If symptoms develop after 65, that is referred to as ‘late-onset,’” said Dr. Szekely, who works closely with the Yale Memory Disorder Clinic and also evaluates patients referred from the Yale Alzheimer's Disease Research Center. “We don’t routinely recommend genetic testing for late-onset dementias unless there is a significant family history, or a patient is planned to receive novel anti-amyloid antibody treatment. However, if you're showing early-onset symptoms or if you have a family history of early-onset disease, a detailed genetic testing is appropriate because there is a much higher chance of the dementia being hereditary. ”
Currently available guidelines typically don’t recommend genetic testing for people who don’t have any symptoms and only have a minor family history of late-onset dementia. The main reason is because of what the test can — and can’t — tell you. The results are complex to interpret. While researchers have identified several genes and their variants that are associated with late-onset Alzheimer's disease, many of these are relatively common gene variants also seen in people who will never develop the disease.
What may matter more is the specific type and grouping of these variants, according to Dr. Szekely. Even then, most of these gene variants only increase your probability of developing the disease. They do not guarantee that you will get it.
“Genetic risk factors are just one of the factors involved in developing Alzheimer's disease. Just because you have one or more of the risk genes, it doesn’t mean we know for sure that you will have it by the time you are 80. With certain lifestyle modifications, you may be able to counteract the risk factors and have a healthy life,” she said.
In other words: Some dementia symptoms may be preventable. You can help reduce your risk by taking these steps:
“Conditions such as high blood pressure, high cholesterol, type 2 diabetes, obesity and alcoholism are additional factors that may impact the development of dementia,” Dr. Szekely said.
If you are concerned that you or a family member may be developing signs of dementia, talk to your primary care provider or a neurologist. The doctor will ask questions about your medical history, perform a physical exam that focuses on neurological function, conduct a series of cognitive assessments and order one or more diagnostic tests. Depending on the results, your doctor may refer you to a neurologist who specializes in memory disorders. If needed, a genetics expert may also participate in your care.
Common signs include:
The complex needs of older patients experiencing dementia symptoms require healthcare professionals with expertise in the field of aging. Yale New Haven Hospital offers a wide range of services for older adults coping with Alzheimer's or other types of dementia. YNHH also offers one of the first and most comprehensive geriatric assessment programs in the United States which evaluates patients with age-related problems — medical, psychological, cognitive and social — that affect daily living. For more information, call 203-785-4085.
