Researchers at the Sant Pau Research Institute in Barcelona have discovered a new genetic form of Alzheimer's disease linked to the APOE4 gene.

The study indicates that having two copies of the APOE4 gene may explain up to 20% of Alzheimer's cases.

APOE4 homozygotes are likely to show higher Alzheimer's biomarkers by 55 and develop symptoms by 65, suggesting rapid progression to impairment.

Findings propose that APOE4 could be a distinct genetic form of Alzheimer's, not just a risk factor.

The discovery could prompt increased APOE4 testing, influence drug development, and lead to personalized treatment and prevention for carriers.

While the study is significant, caution is advised as not all individuals with the genetic marker develop Alzheimer's and treatments need to have broad applicability.

The research was funded by various entities and includes disclosed conflicts of interest from the researchers.