Which Parent Contributes More to Your Alzheimer’s Risk?

June 26, 2024

Who’s more important when it comes to Alzheimer’s risk: your mother or your father? A new study suggests that having a mother who had Alzheimer’s disease may increase your risk more than having a father with the illness.
The study found that people who had a mother with Alzheimer’s disease tended to have higher levels of beta-amyloid in the brain than those who had a father with the disease. The buildup of beta-amyloid, a toxic protein that clumps together to form plaques in the brain, is a hallmark of Alzheimer’s. Having high levels of the protein is associated with an increased risk of the disease.
“Our study found if participants had a family history on their mother’s side, a higher amyloid level was observed,” said study author Dr. Hyun-Sik Yang, a neurologist at Mass General Brigham. 
Having both a mother and father with Alzheimer’s was also associated with higher levels of amyloid in offspring. But having a father with the disease was not linked to higher amyloid levels, unless the father developed Alzheimer’s before age 65.
“If your father had early onset symptoms, that is associated with elevated levels in the offspring,” said Mabel Seto, the study’s first author and a postdoctoral research fellow in the Department of Neurology at Brigham. “However, it doesn’t matter when your mother started developing symptoms — if she did at all, it’s associated with elevated amyloid.”
For the study, researchers at Mass General Brigham and other medical centers around the world looked at 4,413 healthy men and women aged 65 to 85. None had Alzheimer’s or other serious memory problems. All were part of the Anti-Amyloid Treatment in Asymptomatic Alzheimer’s (A4) study, a randomized clinical trial aimed at Alzheimer’s disease prevention. 
Researchers asked participants about whether their parents had Alzheimer’s disease or other serious memory problems and, if so, at what age their symptoms began. Participants also underwent PET scans to assess levels of beta-amyloid in the brain.
The research team found that those with a parental history of Alzheimer’s disease or other serious memory problems on either their mother’s side or both parents’ sides tended to have increased levels of beta-amyloid in their brains. It didn’t matter whether offspring were male or female: both sons and daughters were equally likely to have elevated beta-amyloid levels.
Higher-than-average beta-amyloid levels were also observed in the brains of those who had fathers that were diagnosed with Alzheimer’s before age 65. But the vast majority of Alzheimer’s cases occur after age 65, and later paternal diagnosis did not affect beta-amyloid levels. In contrast, higher levels of beta-amyloid were found in participants regardless of the age of maternal diagnosis.  
Having a parent or other close relative with Alzheimer’s is thought to increase the risk of developing the disease by two to 15 times, depending on the number of relatives affected and specific genes that may have been inherited. But many people whose parents had Alzheimer’s never develop the disease themselves. In addition, many of those with high levels of beta-amyloid in the brain never develop Alzheimer’s.
The good news is that even if you are at increased risk of Alzheimer’s because of family history, there are steps you can take to mitigate the risk. A large analysis from 2020 found that up to 40 percent of cases of Alzheimer’s could be prevented or delayed by targeting 12 modifiable risk factors throughout life. Among the experts’ recommendations:
  1. High blood pressure can increase risk of dementia. Try to keep systolic blood pressure (the top number) to 130 or less from age 40 and beyond.
  2. Good hearing can help to keep the brain sharp. If you are having hearing trouble, make sure to get a hearing aid, and protect the ears from loud noises that can cause permanent damage.
  3. Get regular physical activity throughout life. Starting exercising at any age has benefits that begin immediately.
  4. If you smoke, quit. Quitting smoking at any age can have immediate benefits for brain health and beyond.
  5. Increasingly, experts recognize air pollution as a contributor to Alzheimer’s. Avoid outdoor exercise on days when air quality is poor, and avoid secondhand smoke.
  6. Take measures to avoid head injuries, whether at work or sports. 
  7. If you drink alcoholic beverages, keep it moderate — no more than one to two drinks a day.
  8. Having more years of formal education is linked to a lower Alzheimer’s risk. Stay in school as long as possible, and keep learning to challenge the brain.
  9. Try to maintain a healthy weight, which can lower the risk of diabetes and other chronic ailments tied to dementia.
By ALZinfo.org, The Alzheimer’s Information Site. Reviewed by Eric Schmidt, Ph.D. Fisher Center for Alzheimer’s Research Foundation at The Rockefeller University. 
Source: Mabel Seto, PhD; Timothy J. Hohman, PhD; Elizabeth C. Mormino, PhD; et al: “Parental History of Memory Impairment and Beta-Amyloid in Cognitively Unimpaired Older Adults.” JAMA Neurology, June 17, 2024

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