Even having a distant relative with Alzheimer's disease may increase an individual's risk of developing the condition him-or herself, the Telegraph reports.
A team of Utah-based researchers sifted through the Utah Population Database, which contains genealogical records of Utah pioneers from the 1800s to their modern-day descendants and related data on causes of death. As the researchers reported in Neurology this week, they found that not only did having a first-degree relative with Alzheimer's disease raise someone's risk of the condition, so did having a second- or third-degree relative with Alzheimer's disease. They based their analysis on 270,800 people with three generations of genealogical information in the database.
For instance, they found that someone with two affected first-degree relatives were about four times more likely to develop Alzheimer's disease, while someone with more than three affected third-degree relatives — which included great-grandparents or great aunts or uncles — is 43 percent more likely to develop disease. Individuals with affected first- and second-degree relatives were much more, about 21 times more, likely to develop Alzheimer's disease.
"More and more, people are increasingly seeking an estimate of their own genetic risk for Alzheimer's disease," first author Lisa Cannon-Albright from the University of Utah School of Medicine says in a statement. "Our findings indicate the importance of clinicians taking a person's full family history that extends beyond their immediate family members."