Twin Study Links Dementia to Genetics
Scientists have long pointed to research linking dementia to a person’s genetic history. One of the strongest pieces of scientific evidence is a 2006 study of nearly 12,000 pairs of twins. In that study, researchers linked Alzheimer’s disease to a genetic cause in up to 80 percent of cases. Recently, scientists took their investigation one step further, and studied the incidence of Alzheimer’s disease in identical triplets. Scientists conducted a clinical, genetic and epigenetic investigation of a unique Ashkenazi Jewish family with identical triplets. One of the triplets developed Alzheimer's disease at age 73 and another triplet was diagnosed at age 76. However, the third triplet reached age 85 with no cognitive problems or deficits in daily tasks. Nonetheless, one of this person’s children developed early onset Alzheimer's disease at age 50, while the other children did not report any signs of dementia. So what does this mean? For one thing, scientists concluded that there’s more to the development of dementia than just genetics.Triplet Study Reveals Genetics Not the Only Indicator
"These findings show that your genetic code doesn't dictate whether you are guaranteed to develop Alzheimer's," reports Dr. Morris Freedman, a senior author on the research paper. "There is hope for people who have a strong family history of dementia since there are other factors,” Dr. Freedman adds. “Whether it's the environment or lifestyle, we don't know what it is, which could either protect against or accelerate dementia." When we dig deeper into the research, we find interesting genetic and environmental links to dementia. First, when researchers analyzed the gene sequence taken from the blood of all family members involved in the study, they concluded that the triplet diagnosed with Alzheimer’s disease at age 76 carried the ApoE4 gene. Carrying the ApoE4 gene is known as the single largest risk factor for Alzheimer’s, besides age itself. The presence of ApoE4 is found to increase a person’s risk of developing Alzheimer’s by up to 12 times!2 But researchers couldn’t explain the early onset of Alzheimer’s disease in the child. Then the scientific team discovered that while the triplets were well into their eighties at the time of the study, their cellular biological age was six to ten years younger than their chronological age. On the other hand, the offspring of one of the triplets, the one who developed early onset Alzheimer’s at age 50, had a biological age nine years older than the chronological age. Interestingly, another child of the same triplet parent escaped a dementia diagnosis and showed a biological age close to their actual age. The scientists concluded that lifestyle and environmental factors change your DNA for better or worse. "The latest genetics research is finding 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," says Dr. Ekaterina Rogaeva, another senior author of the study and researcher at the University of Toronto's Tanz Centre for Research in Neurodegenerative Diseases. "As we age, our DNA ages with us and as a result, some cells could mutate and change over time."Understanding How Environment Influences DNA
The study’s authors also note that chemical and environmental factors may not change the gene, per se, but affect how genes are expressed. Now, one set of triplets is extremely slender evidence. We don’t fully understand the role genetics play in Alzheimer’s risk and how we, through our environment and lifestyle, might be able to influence our genetics to either cause or prevent a dementia diagnosis. But in this case, at least, it’s clear that one of the three was able to escape his genetic “fate.” Recently, I wrote an article about another study on this site reporting how scientists identified a rare gene mutation that prevented a Colombian woman from developing Alzheimer’s when virtually every other member of her family had been diagnosed. Scientists said the research, published in the journal Nature Medicine, presents a clue as to why some people resist developing Alzheimer’s when the genetic cards are stacked against them.3 I believe both of these new studies offer hope to you if Alzheimer’s disease runs in your family. The scientific evidence so far suggests that lifestyle and environment can play a role in the development of Alzheimer’s disease. That’s why I recommend a healthy diet and a nutritional supplement regimen that supports brain health. And don’t disregard the value of regular exercise for your body and your brain – perhaps the single most powerful “medicine” to prevent dementia. The point is, keep yourself as healthy as possible. And if you or a loved one does receive a dementia diagnosis, this same approach could slow down the disease progression.- Brain. 2019 Nov 1;142(11):3375-3381. doi: 10.1093/brain/awz289.
- https://www.beingpatient.com/apoe-gene-contribute-alzheimers-scientists-may-found-link/
- https://www.nature.com/articles/s41591-019-0611-3
