World

Alzheimer’s disease is linked to gradual formation of plaques made up of a particular protein in the brain.
These are called senile or amyloid plaques.
They are found close to nerve cells called neurons which are often swollen and distorted.
Scientists for the international pharmaceutical company Elan Pharma developed the vaccine, which is based on a toxic fragment of the main protein in the plaques.
The vaccine causes an immune response to the protein and seems to prevent the development of the plaques, and slow the deterioration of the nerve cells.
In tests, scientists used specially bred mice that carried a human gene, which meant they developed the plaques.
Some were given the vaccine and others were not.
Those who were given the vaccine retained the mental capacity to carry out tests such as finding their way around a maze, the report author Mike Hall told BBC News Online.
Those who were not vaccinated and developed the plaques were unable to successfully complete the memory tests.
Dr Hall said: “If you could vaccinate, you could find those people who are likely to get early onset Alzheimer’s, and hopefully prevent them getting the disease in the first place.”