A new study conducted by researchers in Spain has revealed that people who carry two copies of an Alzheimer’s risk gene could have a significantly higher chance of developing Alzheimer’s disease (AD).
Researchers hope that insights from the study will lead to the development of new treatments and potentially a cure.
Currently the most common form of dementia, AD is a neurodegenerative disease that progressively disrupts memory, cognition, personality and other functions.
Researchers based in Barcelona analysed medical records from over 10,000 people from across the US and Europe, 519 of whom carried two copies of the APOE4 gene, as well as over 3,000 brain samples from people who had donated their brains to research, including 273 people who had carried two copies of APOE4.
Apolipoprotein E (APOE) is a protein that transports fatty molecules such as cholesterol to cells in the brain, to help maintain their structure, obtain energy and communicate with one another.
“Each of us carries two copies of APOE, one inherited from each parent,” meaning that “there are different combinations people can carry,” explained professor Jonathan Schott, chief medical officer at Alzheimer’s Research UK.
The three most common variants of APOE, APOE2, APOE3 and APOE4, are associated with people’s risk of AD in different ways and APOE4 has the biggest impact, with around one in 50 people carrying two copies.
The study revealed that in nearly all APOE4 double-carriers by the age of 65 showed abnormal levels of amyloid in their cerebrospinal fluid and 75% had positive amyloid scans, while analysed brain tissue revealed that almost all APOE4 double-carries had signs of AD in their brains by the age of 55.
In addition, APOE4 double-carriers who did develop AD symptoms developed them around the age of 65, seven to ten years earlier than other APOE variants.
“This study adds compelling data to suggest that people with two copies of this gene are almost guaranteed to develop AD… earlier than people without this gene,” said professor Tara Spires-Jones, Alzheimer’s researcher, University of Edinburgh, who was not involved in the study.
Further research is needed to understand and identify other factors that interact with APOE4.