Tell-tale signs of Alzheimer's 'in twice as many people as thought'
Alzheimer's disease probably affects twice as many people as current estimates suggest, experts believe, but sufferers are yet to show symptoms.
Scientists at the Mayo Clinic in Minnesota have been re-evaluating the prevalence of the disease using brain imaging to give a definitive assessment of the numbers affected.
However, tests on 2,500 people found twice as many as expected had the tell-tale signs of protein plaques and tangles in the brain that are the marks of the disease, even though they were not yet experiencing dementia.
Dr Cliff Jack, a professor of Alzheimer's research at the Mayo Clinic, said the prevalence of the condition was at present "based on clinical assessment, 'do you have dementia?'
"But as a general rule the prevalence of amyloid [protein plaques] and tau [tangles] as denoted by bio-markers is about two times higher," he said. "Classically defined Alzheimer's undercounts people who have the pathology but do not have symptoms."