In a new study, researchers found having second- and third-degree relatives who have had Alzheimer’s may also raise the risk of aging-related brain disease.
Previous studies showed that having a parent with Alzheimer’s disease is linked to a higher risk of developing the disease.
Parents and siblings who share both parents are first-degree relatives.
In the current study, the team examined whether having a second- and third-degree relative with Alzheimer’s disease could influence the disease risk.
Second-degree relatives include blood-related aunts and uncles, grandparents, and siblings who share one parent.
Third-degree relatives include great-grandparents, great aunts, great uncles, and first cousins.
The researchers used data from the Utah Population Database. The database includes the genealogy of Utah pioneers from the 1800s and their descendants up until modern day.
They examined data from more than 270,800 people who had at least three generations of genealogy connected to the original Utah pioneers.
The data included genealogy data for both parents, all four grandparents and at least six of eight great-grandparents.
The researchers found 4,436 people had a death certificate that shows Alzheimer’s disease as a cause of death.
The results showed that people with one first-degree relative with Alzheimer’s disease had a 73% higher risk of developing the disease.
People with two first-degree relatives with Alzheimer’s disease were 4 times more likely to develop the disease.
People with four first-degree relatives with Alzheimer’s disease were nearly 15 times more likely to develop Alzheimer’s.
Moreover, people with one first-degree relative and one second-degree relative with Alzheimer’s disease had a 21 times greater risk.
People with three third-degree relatives with Alzheimer’s disease had a 43% greater risk of developing the disease.
The findings suggest that having a broader view of family history may help predict risk more effectively.
The researchers hope their findings could help develop better diagnoses and help patients and their families in making health-related decisions.
They suggest doctors should take a person’s full family history that extends beyond their immediate family members to predict Alzheimer’s risk.
The lead author of the study is Lisa A. Cannon-Albright, Ph.D., of the University of Utah School of Medicine in Salt Lake City.
The study is published in Neurology, the medical journal of the American Academy of Neurology.
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