In the first study published about Alzheimer’s disease among identical triplets, researchers in Canada suggest that the development of dementia is not exclusively linked to our genes.
The study by scientists at Baycrest and its Rodman Research Institute found that despite sharing the same DNA, only two of the triplets developed Alzheimer’s in their late 70s. At the time of the study, all three of the 85-year-old siblings had high blood pressure but only two ended up developing dementia.
“These findings show that your genetic code doesn’t dictate whether you are guaranteed to develop Alzheimer’s,” said Dr. Morris Freedman, a senior author on the paper, head of neurology at Baycrest and a scientist at Baycrest’s Rotman Research Institute. The paper was published in Brain.
“There is hope for people who have a strong family history of dementia since there are other factors,” he said, “which could either protect against or accelerate dementia.” Other factors, Freedman said, could include environment or lifestyle.
The researchers analyzed the gene sequence from blood that was taken from each of the triplets, as well as the children of one of the triplets with Alzheimer’s.
In further proof that genetics are not solely to blame for Alzheimer’s, among the children, one developed early onset Alzheimer’s disease at age 50 and the other did not report any signs of dementia.
Based on the team’s analysis, the late onset of the Alzheimer’s among the triplets is likely connected to the ApoE4 gene, which has been linked to a higher risk of Alzheimer’s disease.
Another study author, Dr. Ekaterina Rogaeva, a researcher at the University of Toronto’s Tanz Centre for Research in Neurodegenerative Diseases, said that “the DNA we die with isn’t necessarily what we received as a baby, which could relate to why two of the triplets developed Alzheimer’s and one didn’t.”
“As we age, our DNA ages with us and as a result, some cells could mutate and change over time,” she added.
For the last 25 years, the ApoE4 gene, which is a variant of a gene involved in the transportation of cholesterol, has been considered the risk factor most associated with Alzheimer’s after age itself. But scientists are uncovering data that shows we might not fully understand the big picture of how genetics plays into Alzheimer’s risk.
Most recently, researchers identified a rare gene mutation that appeared to prevent a Colombian woman from developing Alzheimer’s. Scientists said the research, published in the journal Nature Medicine, presents a tantalizing clue for why some people are resistant to developing Alzheimer’s.