The first new US diagnostic guidelines for Alzheimer's disease released in 27 years paint the disorder as a disease that occurs gradually over many years, starting with changes in the brain, then mild memory problems and finally progressing to full-blown dementia.
Released on Tuesday by the National Institute on Aging and the Alzheimer's Association, the guidelines officially recognise mild cognitive impairment or MCI as a precursor to the disease.
And they add a new research category known as preclinical Alzheimer's, the earliest stage of the disease when clumps of a protein called amyloid are just beginning to form in the brains of people who are otherwise healthy. This preclinical stage lasts about 10 years before dementia sets in is seen as the best place to intervene in the disease.
The notion of different stages of the disease marks a stark contrast from the last set of guidelines published by government researchers in 1984, which only recognised the dementia phase of Alzheimer's - in which people lose their memories and the ability to care for themselves.
"The biggest difference between then and now is we now think of this process as a continuum that started many years before we make the diagnosis of dementia," Dr Guy McKhann of Johns Hopkins University School of Medicine, who worked on the new guidelines. Including earlier phases of the disease is important in advancing Alzheimer's research, said Dr Reisa Sperling of Brigham and Women's Hospital in Boston.
{{/usCountry}}"The biggest difference between then and now is we now think of this process as a continuum that started many years before we make the diagnosis of dementia," Dr Guy McKhann of Johns Hopkins University School of Medicine, who worked on the new guidelines. Including earlier phases of the disease is important in advancing Alzheimer's research, said Dr Reisa Sperling of Brigham and Women's Hospital in Boston.
{{/usCountry}}"If we are ever really going to move towards prevention of Alzheimer's disease, we have to include people who don't yet have symptoms," Sperling said in a telephone interview.
Sperling said being able to diagnose someone with preclinical Alzheimer's will allow for much earlier treatment and prevention efforts, in much the same way as people with high cholesterol take statin drugs to prevent heart disease.