New guidelines for diagnosing Alzheimer's

>>> for the first time in almost three decades the guidelines that doctors use to diagnose alzheimer's disease are changing. and this now means more than 10 million people in this country could be impacted by the disease . that's almost doubled. as we've been reporting over the years, alzheimer 's is a devastating public health and private family problem. nearly 15 million americans provide care for a loved one suffering from alzheimer 's. an american will develop symptoms every 69 seconds on average. and among those 65 and over, a staggering 1 in 8 americans now has alzheimer 's. our report from our chief science correspondent robert bazell .

>> last year we talked a little bit about your forgetfulness --

>> reporter: the new guidelines recognize alzheimer 's as a disease that unfolds over years, probably decades.

>> one.

>> reporter: and they identify 5 million americans like kippy reeder as having a prealzheimer's condition called mild cognitive impairment , or mci. the guidelines spell out three stages of alzheimer 's. first come changes in the brain with no symptoms. no one knows how many people are affected. mci is the second stage, where people lose some memory but can still function. the third stage is full-blown alzheimer 's, with major memory loss , which afflicts 5.4 million.

>> so that part of the brain's not working very well.

>> reporter: experts like dr. ronald peterson of the mayo clinic say the new guidelines will have little direct benefit for patients now but should lead to better treatments in the future.

>> what we need are the drugs that really go after the underlying disease mechanism itself.

>> we're going to put the blocks together to --

>> reporter: to understand the disease and find those drugs, the mayo clinic has been studying older people over years.

>> finished.

>> now i have four words for you to try to remember .

>> reporter: they undergo memory tests.

>> i didn't remember any of them.

>> reporter: together with brain scans, blood tests , and taps of their spinal fluid .

>> the goal with these scans and many other measurements is to determine exactly what happens in the body as a person progresses from normal memory to mild impairment to full-blown alzheimer's disease .

>> reporter: none of these tests can yet identify people in the early non-symptomatic state, but the scientists hope eventually some will.

>> we're applying sort of the state-of-the-art technology for the prediction and diagnosis of alzheimer's disease .

>> reporter: and the hope is it will eventually lead to drugs to stop the disease before it robs the memory. robert bazell , nbc news, rochester, minnesota.