Researchers know that genetics play a role in Alzheimer’s disease, but there are also other factors that may cause it to occur.

An Alzheimer’s disease diagnosis can be frightening. In the early stages, mild memory loss and mood swings appear. Later, as certain parts of the brain shrink and die, the disease severely limits physical and mental capabilities, and eventually leads to death. If you have a history of Alzheimer’s in your family, here’s what you need to know.

There are two types of Alzheimer’s. Late-onset Alzheimer’s occurs later in life and is thought to be caused by a combination of lifestyle, genetics and environment. Aging is also a factor for this type of the disease, though doctors are still not sure why.

Early-onset Alzheimer’s disease is more rare. It occurs in only five percent of the population who have Alzheimer’s in the United States, but it is especially devastating because it begins to develop much earlier, when people are in their 30s and 40s. In most instances, the disease can be linked to an inherited change in genes.

Fifty percent of Alzheimer’s patients have a relative with the disease, according to Helena Chang Chui, MD with the USC Memory and Aging Center at Keck Medicine of USC and an internationally recognized Alzheimer’s disease expert. “You can be diagnosed with Alzheimer’s if you don’t have a family history, but half of our patients have one family member who had it.”

There is an increased risk if you have a sibling, parent or grandparent with the disease.

Some ethnic groups can carry rare forms of Alzheimer’s. Dr. Chui explained that this type of Alzheimer’s is “autosomal dominant.”

“This means that the disease is caused by a genetic mutation on one of the 23 chromosomes,” said Dr. Chui. “Only one percent of Alzheimer’s patients are autosomal dominant, but one hundred percent of them develop the disease.”

Researchers are still investigating why and when genetic mutations cause Alzheimer’s.

Alzheimer’s cannot be prevented. There is no definitive research about how to prevent the disease. Current recommendations focus on practicing a healthy lifestyle marked by maintaining appropriate weight, good nutrition and exercising. You can also get involved in research trials to help medical experts learn more about the disease.

There are genetic tests that can identify whether you have an increased risk of developing the disease. However, these tests only predict your risk; they can’t confirm that you will actually get it. To be aware of early memory problems, see our recent article on the early warning signs of Alzheimer’s disease.

For more than 30 years, Keck Medicine of USC physicians and researchers have made major contributions to understanding Alzheimer’s disease, vascular brain injury and memory problems.

If you are in the Los Angeles area and interested in genetic testing conducted by some of the top Alzheimer’s specialists in the world, schedule an appointment by calling (800) USC-CARE (800-872-2273) or by visiting http://neuro.keckmedicine.org/request-an-appointment/.

By Heidi Tyline King