In a new study of more than 59,000 people who completed an online memory test, researchers found that adults with a first-degree relative with Alzheimer’s disease performed worse than participants without a family history of the disease.
The findings, published in the journal eLife, also show that this impairment appears to be worsened by having diabetes or a variation in the Alzheimer’s-linked gene called apolipoprotein E (APOE), while being female or having a higher education were seen as protective factors.
Although having a family history of Alzheimer’s is a well-known risk factor for developing the condition, the effects on learning and memory throughout an individual’s life are less clear.
“Identifying factors that reduce or eliminate the effect of a family history of Alzheimer’s disease is particularly crucial since there is currently no cure or effective disease-slowing treatments,” says lead author Joshua Talboom, Ph.D., a Postdoctoral Fellow at the Translational Genomics Research Institute in Arizona.
And while some studies have tackled this subject, most have been too small to draw any significant conclusions. So in order to recruit a large pool of participants, the research team created an easy-to-use website (http://www.mindcrowd.org) where individuals could log on and complete a memory test.
A total of 59,571 participants were asked to learn 12-word pairs and were then tested on their ability to complete the missing half of the pair when presented with one of the words.
The volunteers were also asked to answer questions about their sex, education, age, language, country and health, including a question about whether one of their parents or siblings had been diagnosed with Alzheimer’s disease.
The results show that participants with a family history of Alzheimer’s were able to match about two and one-half fewer word pairs than those without a family history. Having diabetes appeared to compound the learning impairments seen in individuals with a family history.
In addition, a subset of 742 participants who had a close relative with Alzheimer’s submitted a sample of dried blood or saliva that the researchers tested for a genetic variation in the APOE gene linked to the disease.
“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,” Talboom said.
Certain characteristics, however, appeared to protect against memory and learning impairments in people with a family history of Alzheimer’s disease: Those with higher levels of education showed less of a decline in scores on the learning and memory test than people with lower levels of education, even when they have a family history of the disease. Women also appear to fair better despite having Alzheimer’s disease risk factors.
“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,” said senior author Matthew Huentelman, Professor of Neurogenomics at the Translational Genomics Research Institute, Arizona.