Regardless of sex, people younger than age 65 who have a first-degree relative with Alzheimer’s disease generally showed poorer verbal and memory skills on a web-based test than their peers without this family history, a study’s results show.
The study, “Family history of Alzheimer’s disease alters cognition and is modified by medical and genetic factors” was published in the journal eLife.
Researchers at the Translational Genomics Research Institute (Tgen), the Alzheimer’s Prevention Initiative, and the University of Arizona created MindCrowd, a web-based tool that can assess cognitive skills using a word-pair memory test (known as a paired-associated learning task or PAL). Paired-associated learning is dependent on a region of the brain (known as the medial temporal lobe) that is affected early in the course of Alzheimer’s disease, and also altered in the normal aging process.
The MindCrowd study began in 2013, and to date more than 115,000 people worldwide have completed the study’s assessment.
Here, researchers analyzed of 59,571 of those participants (62.46% female and 37.54% male), between 18 to 85 years old, accounting for one of the largest studies evaluating healthy brain function so far.
As family history is a key risk factor for Alzheimer’s disease, the researchers tested the effects of family history on participants’ memory. Family history was determined by a participant acknowledging to have a parent or sibling with an Alzheimer’s diagnosis. A subset of participants also underwent a blood test for a well-established genetic risk factor of Alzheimer’s disease: the ApoE4 gene.
The analysis revealed a family history of Alzheimer’s in 22.76% of the cases. Test results showed that people with Alzheimer’s in a close family member had lower memory test scores and verbal learning test scores than those without this history. This effect was seen in people in their 20s and up to the age of 65.
“In this study we show that family history is associated with reduced paired-associate learning performance as many as four decades before the typical onset of Alzheimer’s disease,” Matt Huentelman, the study’s senior author, said in a press release.
“There was a significant main effect of FH [family history],” the researchers wrote, “for women and men, having FH was associated with nearly two-and-a-half-word pair lower PAL scores when compared to FH- [no family history] participants.”
The impact of family history was also more pronounced among men, as well as those with a lower degree of education, diabetes, and carriers of the ApoE4 gene.
“These data suggest that APOE genotype is an important genetic factor that influences memory,” the researchers wrote.
Overall, “this study supports recommendations underscoring the importance of living a healthy lifestyle, and properly treating disease states such as diabetes,” said Joshua Talboom, the study’s first author.
While the study has limitations, particularly in being a web-based test, “we propose that the advantage of considerably larger sample sizes and enriched participant diversity in online research mostly diminishes the potential disadvantages,” said Lee Ryan, an Alzheimer’s researcher at the University of Arizona.