This explains why these individuals maintain clarity of thought and possess very good memories, according to the Vanderbilt University Medical Center (VUMC) Medical Information Service.
VUMC Assistant Professor Lesley Gaynor said: "We conducted the most comprehensive study on how differences in the structure of the APOE gene affect whether someone will become a long-lived person with a strong memory and a clear mind. We were able to detect differences in the frequency of one of its variants, APOE4, as well as reveal a link between the status of long-lived people and another form of this gene, APOE2."
Geneticists reached this conclusion by studying the genome structure of a group called "centenarians"—elderly people who have maintained sharp minds, strong memories, and a high level of physical activity well into their eighties. These individuals rarely suffer from Alzheimer's disease or other age-related illnesses, attracting the attention of physicians and biologists worldwide.
To uncover the genetic basis of these unusual traits, scientists recruited 1,600 individuals from this group, along with approximately 17,000 of their peers with Alzheimer's disease, as well as participants with normal cognitive function and memory for their age group. The researchers sequenced their genomes and compared variations in the structure of the APOE gene, mutations in which significantly influence the likelihood of developing Alzheimer's disease.
The analysis showed that the pathogenic APOE4 mutation, the presence of which in one or two copies of the APOE gene significantly increases the risk of Alzheimer's disease, was very rare in the DNA of the elderly. On average, it was 68% less common in this group compared to their peers with Alzheimer's disease, and 19% less common compared to 80-year-old participants in the study with normal cognitive function and memory.
The researchers also discovered that the APOE2 mutation, which is believed to reduce the risk of Alzheimer's disease, was 28% more common in centenarians compared to healthy peers, and 103% more common compared to Alzheimer's carriers aged 80 or older.
The scientists indicated that they will conduct further studies of the genomes of centenarians to look for other variations in gene structure that reduce the risk of Alzheimer's disease and other forms of dementia.
