Although the causes of Alzheimer's disease are unknown, it is known that there is a strong genetic relationship, which was previously considered a risk factor. In most cases – That is, without confirming that the person is infected with the disease. The study showed that the risk of developing biological signs in people with the mutation (indicators of the disease observed in exams) ranges between 75 and 95 percent. “To me, this suggests that it's genetically determined,” Sperling says.

The results indicate that 95% of people studied with two copies of the APOE4 gene had the biomarkers of Alzheimer's disease by age 55. The buildup of beta-amyloid protein plaques in the brain is a sign of Alzheimer's disease (where the protein accumulates with dead cells, forming deposits between nerve cells known as senile plaques).

At age 65, symptoms of the disease appeared, such as memory loss and further cognitive decline Signs appear 10 years earlier than usual, the study indicates.

Research says that 2% to 3% of the world's population has a couple of APOE4. These conditions account for 15% to 20% of Alzheimer's diagnoses, according to the study, which could affect a significant portion of patients.

The first signs appear in people at different ages, which also indicates environmental interference in the course of the disease. “Environmental or lifestyle factors can make people's brains more malleable or more vulnerable. This research supports both ideas that genetics is a major driver of Alzheimer's disease, but you can modify your risk of developing symptoms.” [com o estilo de vida]“Sperling says.

It is necessary to expand the base of studied ethnicities. The research used data from mostly European ancestry — and the percentage of people with the mutation varies in other populations, Sperling says.