In a statement, the EU executive announced the authorisation of the drug “under strict conditions”, stipulating that “the medicine is for use in people with only one or no copies of the APOE4 gene and who have beta amyloid plaques in the brain”.

The APOE4 gene is a variant of the APOE gene, which is responsible for instructing the body to produce apolipoprotein (the protein that makes up lipoproteins). The APOE4 variant is associated with the development of Alzheimer’s disease, usually from the age of 65. The disease is characterised by a gradual decline in cognitive abilities, including memory loss.

Beta amyloid plaques are characteristic of Alzheimer’s and “stifle” communication between nerve cells.

The European Commission’s authorisation for the use of Leqembi comes after a positive assessment by the European Medicines Agency (EMA), “which concluded that the benefits of this drug outweigh the risks”, but only within a “patient population” and with “risk minimisation” measures in place.

According to information made available by the non-profit organisation European Brain Council at the beginning of 2025, there are around seven million people with Alzheimer’s disease in Europe, and the number is expected to double by 2030.