Alzheimer's disease might be transmissible through blood transfusions and medical accidents in the same way as Creuzfeldt Jakob disease (CJD), scientists believe. In a landmark finding that has been described as leading to a "paradigm shift", researchers at University College London said it was possible that the "seeds" of dementia could be transferred from the brain tissue of one person to another.The proteins that cause dementia are prions, which can stick to metals, such as those from which surgical instruments are made.They are resistant to conventional sterilisation methods.This means that it would be possible to be infected with Alzheimer's through a blood transfusion, brain surgery, or invasive dental work, such as a root canal operation.Because the incubation period can be up to 40 years, people could be unaware that they have been contaminated.The UK government's chief medical officer, Sally Davies, said the Department of Health was monitoring the situation and assured the public that there was little risk.British scientists stumbled on the discovery while studying the brains of eight people who died of CJD. All had developed the disease after being injected with human growth hormone taken from corpses."What we need to consider is that, in addition to there being sporadic Alzheimer's disease and inherited or familial Alzheimer's disease, there could also be acquired forms," said lead scientist John Collinge, director of the Medical Research Council's prion unit at the university...