Overgrowth of blood vessels in the brain may help to explain the damage caused by Alzheimer\'s disease, new research suggests Thursday. Scientists believe the profusion of blood vessels may lead to a breakdown of the \"blood-brain barrier.\" This is a tightly interlocked \"wall\" of cells that allows oxygen-carrying blood to reach brain tissue while blocking harmful substances and invaders such as viruses. Evidence of the role of blood vessels in Alzheimer\'s was found in laboratory mice with their own version of the disease. Scientists believe the blood vessel growth is stimulated by beta amyloid, a type of protein that is a hallmark of Alzheimer\'s and accumulates in the brains of sufferers. The research is published today in the online journal Public Library of Science ONE. Lead researcher Professor Wilfred Jefferies, from the University of British Columbia in Canada, said: \"When the blood vessels grow, the cells of the vessel walls propagate by dividing. \"In the process of splitting into two new cells, they become temporarily rounded in shape, and that undermines the integrity of the blood-brain barrier, potentially allowing harmful elements from outside the brain to seep in.\" Deterioration of the barrier might, in turn, allow beta amyloid to deposit itself around neurons and eventually kill them. There is a parallel with the \"wet\" form of the sight disorder age-related macular degeneration, in which blood vessels grow behind the retina, Prof Jefferies believes. \"The next logical step in the treatment of Alzheimer\'s disease would be to look for treatments that specifically target blood vessel growth,\" he said. Alzheimer\'s is the most common form of dementia, affecting 62% of 750,000 sufferers in the UK. Dr Susanne Sorensen, head of research at the Alzheimer\'s Society, said: \"Identifying early changes that can be easily measured in people with Alzheimer\'s is one of the big challenges for scientists trying to develop treatments and, ultimately, a cure. \"This new research builds on existing knowledge and points towards an exciting new avenue of investigation. \"This could one day pave the way towards a better future for hundreds of thousands of people\".