Having close relatives with Alzheimer’s disease is linked to poorer memory, a new study has found.
The study, titled “Family history of Alzheimer’s disease alters cognition and is modified by medical and genetic factors,” was published in eLIFE.
Having a family history of Alzheimer’s disease and dementia are known risk factors for developing these conditions, but it’s less clear how such a predisposition might affect cognition throughout life. Although some studies have investigated this association, most have been too small to draw reliable conclusions.
A team of researchers at the Translational Genomics Research Institute in Arizona created a website — MindCrowd — to perform memory tests on a massive scale. Participants were asked questions about themselves, such as their sex, education, age, and whether they had any first-degree biological relatives (parents, siblings) with Alzheimer’s. They then completed a memory test where they were given 12 word pairs and when given one of the words later, they had to recall the other word in the pair.
In total, 59,571 people (aged 18–85) completed the tests. Participants were from all over the world — most of them were in the United States and Europe — predominantly female (62.46%), and white (92.03%).
On average, people with a first-degree relative with Alzheimer’s and under 65 years old correctly matched 2.5 fewer word pairs than people without such relatives. This effect was particularly strong among males and among people who had diabetes.
The effect was seen at all levels of education. However, the gap between people with and without first-degree relatives with Alzheimer’s decreased among people who had received more formal education. In other words, there is evidence of a predisposition towards worse memory, but also a reminder that genetics are not destiny.
“Our study supports the importance of living a healthy lifestyle, properly treating diseases such as diabetes, and building learning and memory reserve through education to reduce the cognitive decline associated with Alzheimer’s disease risk factors,” Matthew Huentelman, PhD, a professor at the Translational Genomics Research Institute and co-author of the study, said in a press release.
The researchers also obtained genetic data (via blood or saliva sample) for a subset of 742 participants who had a first-degree relative with Alzheimer’s. They focused on the APOE gene, a variant of which (ApoE4) is linked to a higher Alzheimer’s risk. This variant was associated with an average of one and a third fewer correct word pairs for each copy of the gene (one from each parent) that had it.
“The APOE genotype is an important genetic factor that influences memory, and we found that those with the variation performed worse on the memory test than those without the variation,” said Joshua Talboom, PhD, a postdoctoral fellow at the institute and study co-author.
“Collectively, this study supports recommendations underscoring the importance of living a healthy lifestyle, properly treating disease states such as diabetes, and building cognitive reserve through education (i.e., risk reduction) to attenuate age- and [Alzheimer’s disease]-risk-related cognitive declines,” the researchers wrote.
They further added that these findings highlight the positive effects of such interventions on first-degree family history of dementia, “opening the door to the development of more targeted risk reduction approaches to combat [Alzheimer’s disease].”
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