New Study Links Alzheimer’s Cases to a Gene Variation
A recent study indicates that over 90% of Alzheimer’s cases may be linked to variations in a single gene and the protein it produces. This new insight suggests that targeting this gene could help prevent the disease in most individuals.
The gene in focus, APOE, has long been tied to the risk of developing Alzheimer’s. What’s particularly interesting in this study is how the different variations of APOE have been examined in relation to Alzheimer’s risk. It appears that the specific APOE variant we inherit might play a more critical role than previously thought.
Researchers from University College London (UCL) revisited the three main variations of the APOE gene: ε2 (which seems to offer some protection against cognitive decline), ε3 (viewed historically as neutral), and ε4 (known to heighten Alzheimer’s risk significantly).
Analyzing data from genetic records of nearly 470,000 individuals, the researchers discovered that ε3 isn’t truly neutral; rather, it acts as a significant risk factor. This finding might not have been recognized earlier since ε3 is the most common variant, appearing in about 75% of people.
“When evaluating the roles of ε3 and ε4, it becomes clear that APOE can have an impact on nearly all Alzheimer’s cases,” observes Dylan Williams, a genetic epidemiologist at UCL.
“While the ε4 variant is known as harmful, much of the disease wouldn’t occur without considering the influence of the prevalent ε3 allele, which has often been mischaracterized as neutral in terms of its risk for Alzheimer’s.”
Individuals inherit two copies of the APOE gene, one from each parent, leading to six potential combinations. The ε2 / ε2 combination is most protective against Alzheimer’s, while ε4 / ε4 significantly raises the risk. Most people fall somewhere in between based on their unique genetic inheritance.
This specific APOE combination impacts how the associated protein functions, which in turn affects various brain activities that relate to Alzheimer’s, such as neuron repair, inflammation management, and clearing away amyloid-beta protein plaques.
The researchers propose that focusing on this gene or its protein products could be a strategy to prevent Alzheimer’s from developing in the first place, potentially lowering the risk to levels associated with ε2 / ε2.
“Targeting the APOE gene directly, or the pathways linking it to the disease, could significantly help prevent or treat the majority of Alzheimer’s cases,” adds Williams.
Interestingly, the implications may extend even further: nearly half of all dementia cases might be connected to the APOE gene, according to their findings.
However, these genetic risks don’t operate in a vacuum. Environmental and lifestyle factors, like obesity, social isolation, and inadequate sleep, likely interact with genetic risks in complex ways that we’re still trying to piece together.
Nevertheless, this study emphasizes that the presence of ε3 and ε4 variants plays a more significant role than previously believed.
“Without the contributions of APOE ε3 and ε4, many cases of Alzheimer’s are unlikely to occur, regardless of other inherited traits or life experiences,” Williams states based on their population data.
There’s still a long road ahead for researchers aiming to explore the potential of APOE. Gene targeting doesn’t come easily, and any gene therapies need to be approached with caution.
Yet, these findings could mark a notable shift in Alzheimer’s research, which has faced challenges in uncovering effective treatments.
“For complex diseases like Alzheimer’s, there are likely multiple avenues to reduce the risk,” Williams notes. “We should investigate a variety of strategies that could alter the risk of Alzheimer’s and dementia, including those tied to APOE.”
This research has been published in NPJ Dementia.
