Protective protein can help fight against Alzheimer’s disease

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A PROTEIN that protects people against Alzheimer’s disease has been discovered by experts, opening the door to a new 
treatment.

Scientists screened the DNA of almost 2,000 people and found those with a mutated form of a particular gene were less likely to develop dementia.

Mimicking this variant with a drug could stop Alzheimer’s in its tracks, say neurologists whose findings are published in Nature.

The gene in question is known as “APP” (“amyloid precursor protein”) and makes a chemical called amyloid-beta which sticks together in the brain and blocks neurons from communicating with each other.

The onset of the disease has been linked to such clumps which form when fragments of the protein gather together and cause the classic symptoms such as memory loss and speech problems.

Mutations in the APP gene have already been implicated in early-onset Alzheimer’s, but had not been linked to the common form of the disease that occurs in later life.

Dr Kari Stefansson, chief executive of Icelandic company deCODE Genetics in Reykjavik, said the research supports the theory that modifying the gene, which can be achieved with existing drugs, may prevent 
dementia.

Dr Stefansson said: “The prevalence of dementia in the Western world in people over the age of 60 has been estimated to be greater than 5 per cent, about two-thirds of which are due to Alzheimer’s disease.

“The age-specific prevalence of Alzheimer’s disease nearly doubles every five years after age 65, leading to a prevalence of greater than 25 per cent in those over the age of 90.

“We found a coding mutation in the APP gene that protects against Alzheimer’s disease and cognitive decline in the elderly without Alzheimer’s disease.”

Meanwhile, scientists in America say scans can detect Alzheimer’s decades before problems with memory and thinking develop.

Professor Randall Bateman, of Washington University, St Louis, said: “A series of changes begins in the brain decades before the symptoms of Alzheimer’s disease are noticed by patients or families, and this cascade of events may provide a timeline for symptomatic onset.”

He hopes to launch Alzheimer’s prevention and treatment trials later this year.

His study published in The New England Journal of Medicine evaluated a variety of pre-symptomatic markers of Alzheimer’s in 128 subjects from families genetically predisposed to develop the disorder. Using medical histories of the subjects’ parents to predict the age of the onset of symptoms, the scientists assembled a timeline of changes in the brain leading to the memory loss and cognitive decline that characterises the disease.