Author: Chloe Wilcox
It may be common knowledge that having an immediate family member, such as a parent, with Alzheimer’s can increase your risk of developing the disease. However, new research suggests that we may want to pay closer attention to our extended family as well.
A new study published online in the March 13, 2019 issue of Neurology looked to determine the degree to which extended family can indicate risk for Alzheimer’s disease.
“You could just ask about first degree relatives, but you’re not going to understand someone’s risk unless you go out a bit further,” explained Lisa Cannon-Albright, PhD, professor and Program Leader of Genetic Epidemiology at University of Utah Health. Cannon-Albright coordinated with fellow researchers from Brigham Young University and Utah State University to conduct the study. “We can go into much more detail about family history, and we decided that that would be clinically useful for Alzheimer's.”
The researchers considered first-, second-, and third-degree relatives for immediate and extended family. First-degree relatives refer to parents, offspring, and siblings who share the same parents. Second-degree relatives refer to grandparents/grandchildren, blood-related aunts and uncles and nieces and nephews, as well as siblings who share one parent. Third-degree relatives include first cousins, great-grandparents/great-grandchildren, great uncles, and great aunts, great nieces and great nephews.
Cannon-Albright and her collaborators conducted a statistical analysis looking at the Utah Population Database, including genealogy dating back to the Utah founders in the 1800s. The database is the thread linking these pioneers to their modern-day descendants and allows the researchers to access Utah death certificates that include causes and contributing causes of death.
“We were able to find that the risk for developing Alzheimer’s was significantly increased for each additional relative affected by the disease,” recounted Cannon-Albright, who described the team’s surprise to learn that even a third-degree relative affected risk. “It’s interesting to think about the fact that shared genes are enough to show that your risk is affected.”
The results showed that the risk of an individual with one first-degree relative and one second-degree relative diagnosed with Alzheimer’s was 21 times greater than the population rate for developing the disease. In addition, an individual with a negative history of Alzheimer’s among first-degree relatives but positive history among three or more second-degree relatives still has a two-fold increase in risk and a 17–44 percent increase in risk for those with two or more third-degree relatives.
Looking ahead, Cannon-Albright discussed the benefits of using similar statistical analysis in combination with family history to examine other diseases. She went on to explain that Utah could be a very effective place to do genetic studies and powerful risk prediction, based on the ability to understand and utilize family history information. When asked about working with her fellow researchers, Cannon-Albright insisted that they are “very motivated and enthusiastic, so the Alzheimer’s research is going in a lot of different directions.”
Lastly, Cannon-Albright explained why this new research might be important or impactful to patients or the general public. “Perhaps if individuals knew that Alzheimer’s was something they might have to face, they could be better mentally prepared,” she said.
Beyond mental preparedness, Cannon-Albright touched on the practical implications of extended family histories in clinical settings. Primary care providers are in a prime position to educate and recommend lifestyle changes after the knowledge of increased risk revealed by a patient.
“Clinicians are the front line,” Cannon-Albright said. “Most patients could easily communicate family history and determine risk.”
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Cannon-Albright was joined in this study by Norman Foster, Karen Schliep, James Farnham, Craig Teerlink, and Heydon Kaddas of U of U Health; JoAnn Tschanz and Chris Corcoran at Utah State University; and John Kauwe at Brigham Young University. The study was supported by the National Institutes of Health and the National Cancer Institute.